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  • CLASSES

    Anticholinergics/Antispasmodics for Functional Bowel Disorders

    DEA CLASS

    Rx

    DESCRIPTION

    Oral, quaternary anticholinergic gastrointestinal agent
    Historical agent; limited use as adjunct therapy in the management of peptic ulcer disease
    More effective agents currently available (PPIs, H2-blockers)

    COMMON BRAND NAMES

    Cantil

    DOSAGE & INDICATIONS

    For use as adjunctive therapy in the treatment of duodenal ulcer or gastric ulcer.
    NOTE: This drug not been shown to be effective in contributing to the healing of peptic ulcer, decreasing the rate of recurrence, or preventing complications.
    Oral dosage
    Adults

    25 to 50 mg PO 4 times per day with meals and at bedtime. Initiate treatment at lowest dose possible and adjust according to clinical response.

    Geriatrics

    25 to 50 mg PO 4 times per day with meals and at bedtime. Initiate treatment at the lowest dose and adjust according to clinical response. Use caution in geriatric patients.

    MAXIMUM DOSAGE

    Adults

    200 mg/day PO.

    Geriatric

    200 mg/day PO.

    Adolescents

    Safety and efficacy have not been established.

    Children

    Safety and efficacy have not been established.

    Infants

    Safety and efficacy have not been established.

    Neonates

    Safety and efficacy have not been established.

    DOSING CONSIDERATIONS

    Hepatic Impairment

    Caution should be used when administering mepenzolate to patients with hepatic disease; however, specific guidelines for dosage adjustments in hepatic impairment are not available.

    Renal Impairment

    Caution should be used when administering mepenzolate to patients with renal disease; however, specific guidelines for dosage adjustments in renal impairment are not available.

    ADMINISTRATION

    Oral Administration
    Oral Solid Formulations

    Administer mepenzolate with meals and at bedtime.

    STORAGE

    Cantil:
    - Avoid excessive heat (above 104 degrees F)
    - Store below 86 degrees F

    CONTRAINDICATIONS / PRECAUTIONS

    Bromide hypersensitivity, tartrazine dye hypersensitivity

    Mepenzolate should not be used in any patient with a known or suspected hypersensitivity to mepenzolate or any related drugs including atropine, homatropine, scopolamine and other belladonna alkaloids. Mepenzolate bromide is contraindicated in patients with bromide hypersensitivity. In addition, Cantil brand mepenzolate tablets contain tartrazine, which may cause allergic-type reactions (including bronchial asthma) in patients with tartrazine dye hypersensitivity. Although the overall incidence of tartrazine sensitivity in the general population is low, it is frequently seen in patients who also have aspirin sensitivity.

    Geriatric

    Mepenzolate is contraindicated in intestinal atony of the geriatric or debilitated patient. In general, geriatric patients are more susceptible to anticholinergic effects. Mepenzolate should be used with caution in the elderly. Dose selection for an elderly patient should start at the low end of the dosing range, considering the likelihood of decreased hepatic, renal or cardiac function and of concomitant disease or other drug therapy.

    Contact lenses, glaucoma

    Mepenzolate is contraindicated in patients with glaucoma because it produces mydriasis and cycloplegia which can increase intraocular pressure. Elderly patients are more susceptible to anticholinergic effects, including possible precipitation of undiagnosed glaucoma. The anticholinergic effects of mepenzolate may make the eyes dry and this can cause irritation or blurred vision for wearers of contact lenses. The use of lubricating drops may be necessary, or in severe cases the patient may need to discontinue the use of contact lenses while taking mepenzolate.

    Bladder obstruction, prostatic hypertrophy, urinary retention, urinary tract obstruction

    Mepenzolate is contraindicated in patients with urinary tract obstruction or bladder obstruction due to prostatic hypertrophy because it can cause urinary retention via its antimuscarinic effects on the ureters and bladder. Mepenzolate should be used with caution in patients with prostatic hypertrophy because it can exacerbate urinary retention.

    Achalasia, esophagitis, gastroesophageal reflux disease (GERD), GI obstruction, hiatal hernia, ileus, pyloric stenosis, toxic megacolon, ulcerative colitis

    The anti-motility effects of mepenzolate on the gastrointestinal tract may exacerbate a number of gastrointestinal disorders. For this reason, mepenzolate is contraindicated in patients with GI obstruction, pyloric stenosis, achalasia, paralytic ileus including intestinal atony of the elderly or debilitated patient, and toxic megacolon complicating ulcerative colitis. Of note, diarrhea may be an early symptom of incomplete intestinal obstruction especially in patients with ileostomy or colostomy. Use caution in patients with ulcerative colitis as suppressed intestinal motility caused by large doses of mepenzolate may produce a paralytic ileus and precipitate or aggravate toxic megacolon in these patients. Mepenzolate should also be used cautiously in patients with gastroesophageal reflux disease (GERD) or hiatal hernia associated with reflux esophagitis. The reduced gastric motility and relaxation of the lower esophageal sphincter caused by mepenzolate can promote gastric retention and aggravate reflux in these patients.

    Cardiac arrhythmias, cardiac disease, coronary artery disease, GI bleeding, heart failure, hemorrhagic shock, hypertension, hyperthyroidism, tachycardia

    Mepenzolate can cause tachycardia secondary to cholinergic antagonism at the SA node. Tachycardia due to mepenzolate can increase the oxygen demand on the heart in patients with pre-existing cardiac disease such as hypertension, coronary artery disease, cardiac arrhythmias, congestive heart failure, and should be used cautiously in these patients. Patients with tachycardia or tachyarrhythmia are also at risk for adverse cardiovascular events when taking mepenzolate. In addition, patients with hyperthyroidism may also be at an increased risk for adverse cardiovascular effects, and mepenzolate should be used with caution in these patients. Mepenzolate is also contraindicated in patients who exhibit unstable cardiovascular status in acute GI bleeding (i.e., hemorrhagic shock).

    Autonomic neuropathy, myasthenia gravis

    Mepenzolate is contraindicated in patients with myasthenia gravis and should be used with caution in autonomic neuropathy because the drug competes with the small amount of acetylcholine that has potential to act in the body.

    Hepatic disease, renal disease, renal impairment

    Because data are lacking in patients with renal disease or hepatic disease, mepenzolate should be used with caution in patients with organ dysfunction. No specific guidelines are available for dosing mepenzolate in patients with renal impairment or hepatic impairment.

    Chronic obstructive pulmonary disease (COPD), pulmonary disease

    Anticholinergics, such as mepenzolate, can decrease and thicken bronchial secretions and should be used cautiously in patients with chronic pulmonary disease including chronic obstructive pulmonary disease (COPD). Inspissation and formation of bronchial plugs may occur in these patients.

    Ambient temperature increase, dehydration

    Insensitivity to heat (fever, diaphoresis) may occur when mepenzolate is administered in the presence of high environmental temperatures. Patients should avoid dehydration or exposure to an extreme ambient temperature increase to avoid heat stroke.

    Driving or operating machinery, ethanol intoxication

    Anticholinergic medications may cause blurred vision, drowsiness, or dizziness, especially with initial use. Patients should use caution when driving or operating machinery until they know how mepenzolate affects them. Ethanol intoxication can magnify sedative effects and is best avoided.

    Pregnancy

    Mepenzolate is classified as FDA pregnancy risk category B. Animal studies show no evidence of fetal harm. However, no adequate and well-controlled studies with mepenzolate in pregnant women exist. In one large prospective study, 2323 patients were exposed to mepenzolate and other drugs within the same class during the first trimester of pregnancy; only 1 patient was exposed to mepenzolate. A possible association between the total treatment group and minor malformations was found. Therefore, in making the decision to administer this drug during pregnancy, the potential risks to the fetus must be weighed against the potential benefits to the mother.

    Breast-feeding

    According to the manufacturer, it is not known whether mepenzolate is excreted in human milk and therefore caution should be exercised when mepenzolate is administered during breast-feeding. Similar to other drugs with anticholinergic properties, mepenzolate may theoretically suppress lactation. In addition, neonates and infants are usually more sensitive to the anticholinergic effects of drugs. Consider the benefits of breast-feeding, the risk of potential infant drug exposure, and the risk of an untreated or inadequately treated condition. If a breast-feeding infant experiences an adverse effect related to a maternally ingested drug, healthcare providers are encouraged to report the adverse effect to the FDA.

    Children, infants, neonates

    The safety and efficacy of mepenzolate in neonates, infants, children, and adolescents have not been established.

    ADVERSE REACTIONS

    Severe

    coma / Early / Incidence not known
    ocular hypertension / Delayed / Incidence not known
    anaphylactoid reactions / Rapid / Incidence not known

    Moderate

    blurred vision / Early / 1.0-10.0
    urinary retention / Early / 1.0-10.0
    constipation / Delayed / 10.0
    euphoria / Early / Incidence not known
    hallucinations / Early / Incidence not known
    dysarthria / Delayed / Incidence not known
    ataxia / Delayed / Incidence not known
    confusion / Early / Incidence not known
    cycloplegia / Early / Incidence not known
    sinus tachycardia / Rapid / Incidence not known
    palpitations / Early / Incidence not known
    impotence (erectile dysfunction) / Delayed / Incidence not known
    heat intolerance / Early / Incidence not known
    anhidrosis / Delayed / Incidence not known
    hyperthermia / Delayed / Incidence not known
    lactation suppression / Early / Incidence not known

    Mild

    dizziness / Early / 1.0-10.0
    drowsiness / Early / 1.0-10.0
    mydriasis / Early / 1.0-10.0
    xerostomia / Early / 10.0
    headache / Early / 10.0
    vomiting / Early / Incidence not known
    dysgeusia / Early / Incidence not known
    nausea / Early / Incidence not known
    agitation / Early / Incidence not known
    insomnia / Early / Incidence not known
    fatigue / Early / Incidence not known
    weakness / Early / Incidence not known
    urticaria / Rapid / Incidence not known
    fever / Early / Incidence not known

    DRUG INTERACTIONS

    Acetaminophen; Butalbital; Caffeine; Codeine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when codeine is used concomitantly with an anticholinergic drug. The concomitant use of codeine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Acetaminophen; Caffeine; Dihydrocodeine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when dihydrocodeine is used concomitantly with an anticholinergic drug. The concomitant use of dihydrocodeine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Acetaminophen; Caffeine; Magnesium Salicylate; Phenyltoloxamine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Acetaminophen; Caffeine; Phenyltoloxamine; Salicylamide: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Acetaminophen; Chlorpheniramine; Dextromethorphan; Phenylephrine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Acetaminophen; Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Acetaminophen; Chlorpheniramine; Phenylephrine; Phenyltoloxamine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Acetaminophen; Codeine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when codeine is used concomitantly with an anticholinergic drug. The concomitant use of codeine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Acetaminophen; Dextromethorphan; Doxylamine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Acetaminophen; Diphenhydramine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Acetaminophen; Hydrocodone: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when hydrocodone is used concomitantly with an anticholinergic drug. The concomitant use of hydrocodone and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Acetaminophen; Oxycodone: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when oxycodone is used concomitantly with an anticholinergic drug. The concomitant use of oxycodone and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Acetaminophen; Pentazocine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when pentazocine is used concomitantly with an anticholinergic drug. The concomitant use of pentazocine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Acetaminophen; Tramadol: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when tramadol is used concomitantly with an anticholinergic drug. The concomitant use of tramadol and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Aclidinium: (Moderate) Although aclidinium is minimally absorbed into the systemic circulation after inhalation, there is the potential for aclidinium to have additive anticholinergic effects when administered with other anticholinergics or antimuscarinics.Per the manufaturer, avoid concomitant administration of aclidinium with other anticholinergic medications, when possible.
    Acrivastine; Pseudoephedrine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Albuterol; Ipratropium: (Moderate) Although ipratropium is minimally absorbed into the systemic circulation after inhalation, there is the potential for tiotropium to have additive anticholinergic effects when administered with other antimuscarinics. Per the manufaturer, avoid concomitant administration of ipratropium with other anticholinergic medications, such as antimucarinics.
    Alfentanil: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when alfentanil is used concomitantly with an anticholinergic drug. The concomitant use of alfentanil and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Alosetron: (Major) Concomitant use of alosetron and anticholinergics, which can decrease GI motility, may seriously worsen constipation, leading to events such as GI obstuction, impaction, or paralytic ileus. Although specific recommendations are not available from the manufacturer, it would be prudent to avoid anticholinergics in patients taking alosetron.
    Aluminum Hydroxide: (Moderate) Antacids may inhibit the oral absorption of anticholinergics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Aluminum Hydroxide; Magnesium Carbonate: (Moderate) Antacids may inhibit the oral absorption of anticholinergics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Aluminum Hydroxide; Magnesium Hydroxide: (Moderate) Antacids may inhibit the oral absorption of anticholinergics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Aluminum Hydroxide; Magnesium Hydroxide; Simethicone: (Moderate) Antacids may inhibit the oral absorption of anticholinergics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Aluminum Hydroxide; Magnesium Trisilicate: (Moderate) Antacids may inhibit the oral absorption of anticholinergics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Amantadine: (Moderate) Medications with significant anticholinergic activity may potentiate the anticholinergic effects of amantadine, and may increase the risk of antimuscarinic-related side effects.
    Amoxapine: (Moderate) Depending on the specific agent, additive anticholinergic effects may be seen when amoxapine is used concomitantly with other anticholinergic agents. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive CNS effects are also possible when these drugs are combined with amoxapine.
    Amyl Nitrite: (Moderate) Additive anticholinergic effects may be seen when mepenzolate is used concomitantly with nitrates. Clinicians should note that antimuscarinic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur.
    Antacids: (Moderate) Antacids may inhibit the oral absorption of anticholinergics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Anxiolytics; Sedatives; and Hypnotics: (Moderate) CNS depression can be increased when mepenzolate is combined with other CNS depressants such as any anxiolytics, sedatives, and hypnotics.
    Apraclonidine: (Moderate) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Articaine; Epinephrine: (Moderate) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Aspirin, ASA; Butalbital; Caffeine; Codeine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when codeine is used concomitantly with an anticholinergic drug. The concomitant use of codeine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Aspirin, ASA; Caffeine; Dihydrocodeine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when dihydrocodeine is used concomitantly with an anticholinergic drug. The concomitant use of dihydrocodeine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Aspirin, ASA; Carisoprodol: (Moderate) CNS depression can be increased when mepenzolate is combined with other CNS depressants such as skeletal muscle relaxants.
    Aspirin, ASA; Carisoprodol; Codeine: (Moderate) CNS depression can be increased when mepenzolate is combined with other CNS depressants such as skeletal muscle relaxants. (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when codeine is used concomitantly with an anticholinergic drug. The concomitant use of codeine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Aspirin, ASA; Oxycodone: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when oxycodone is used concomitantly with an anticholinergic drug. The concomitant use of oxycodone and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Atomoxetine: (Moderate) Mepenzolate and atomoxetine should be combined cautiously in patients with known cardiac disease. Mepenzolate may alter the heart rate; the predominant clinical effect is sinus tachycardia. An additive effect on heart rate may occur as atomoxetine may elevate heart rate as well as blood pressure.
    Atracurium: (Moderate) CNS depression can be increased when mepenzolate is combined with other CNS depressants such as neuromuscular blockers.
    Azelastine; Fluticasone: (Minor) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Baclofen: (Moderate) CNS depression can be increased when mepenzolate is combined with other CNS depressants such as skeletal muscle relaxants.
    Beclomethasone: (Minor) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Belladonna; Opium: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when opium is used concomitantly with an anticholinergic drug. The concomitant use of opium and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Betamethasone: (Minor) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Botulinum Toxins: (Moderate) The use of systemic antimuscarinic/anticholinergic agents following the administration of botulinum toxins may result in a potentiation of systemic anticholinergic effects (e.g., blurred vision, dry mouth, constipation, or urinary retention).
    Brimonidine: (Moderate) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Brimonidine; Brinzolamide: (Moderate) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Brimonidine; Timolol: (Moderate) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Brompheniramine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Brompheniramine; Carbetapentane; Phenylephrine: (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants including anticholinergics. (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Brompheniramine; Dextromethorphan; Guaifenesin: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Brompheniramine; Guaifenesin; Hydrocodone: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when hydrocodone is used concomitantly with an anticholinergic drug. The concomitant use of hydrocodone and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect. (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Brompheniramine; Hydrocodone; Pseudoephedrine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when hydrocodone is used concomitantly with an anticholinergic drug. The concomitant use of hydrocodone and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect. (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Brompheniramine; Pseudoephedrine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Budesonide: (Minor) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Budesonide; Formoterol: (Minor) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Buprenorphine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when buprenorphine is used concomitantly with an anticholinergic drug. The concomitant use of buprenorphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Buprenorphine; Naloxone: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when buprenorphine is used concomitantly with an anticholinergic drug. The concomitant use of buprenorphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Bupropion: (Moderate) Additive anticholinergic effects may be seen when mepezolate is used concomitantly with bupropion. Additive drowsiness may occur. Clinicians should note that antimuscarinic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation.
    Bupropion; Naltrexone: (Moderate) Additive anticholinergic effects may be seen when mepezolate is used concomitantly with bupropion. Additive drowsiness may occur. Clinicians should note that antimuscarinic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation.
    Butorphanol: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when butorphanol is used concomitantly with an anticholinergic drug. The concomitant use of butorphanol and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Calcium Carbonate: (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Calcium Carbonate; Magnesium Hydroxide: (Moderate) Antacids may inhibit the oral absorption of anticholinergics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction. (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Calcium Carbonate; Risedronate: (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Calcium; Vitamin D: (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Capsaicin; Metaxalone: (Moderate) CNS depression can be increased when mepenzolate is combined with other CNS depressants such as skeletal muscle relaxants.
    Carbetapentane; Chlorpheniramine: (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants including anticholinergics. (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Carbetapentane; Chlorpheniramine; Phenylephrine: (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants including anticholinergics. (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Carbetapentane; Diphenhydramine; Phenylephrine: (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants including anticholinergics. (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Carbetapentane; Guaifenesin: (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants including anticholinergics.
    Carbetapentane; Guaifenesin; Phenylephrine: (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants including anticholinergics.
    Carbetapentane; Phenylephrine: (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants including anticholinergics.
    Carbetapentane; Phenylephrine; Pyrilamine: (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants including anticholinergics. (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Carbetapentane; Pseudoephedrine: (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants including anticholinergics.
    Carbetapentane; Pyrilamine: (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants including anticholinergics. (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Carbinoxamine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Carbinoxamine; Dextromethorphan; Pseudoephedrine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Carbinoxamine; Hydrocodone; Phenylephrine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when hydrocodone is used concomitantly with an anticholinergic drug. The concomitant use of hydrocodone and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect. (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Carbinoxamine; Hydrocodone; Pseudoephedrine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when hydrocodone is used concomitantly with an anticholinergic drug. The concomitant use of hydrocodone and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect. (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Carbinoxamine; Phenylephrine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Carbinoxamine; Pseudoephedrine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Carisoprodol: (Moderate) CNS depression can be increased when mepenzolate is combined with other CNS depressants such as skeletal muscle relaxants.
    Cetirizine: (Moderate) Dry mouth and drowsiness were more common in patients receiving cetirizine/levocetirizine vs. placebo, and caution may be necessary during concomitant use of cetirizine/levocetirizine with the antimuscarinics.
    Cetirizine; Pseudoephedrine: (Moderate) Dry mouth and drowsiness were more common in patients receiving cetirizine/levocetirizine vs. placebo, and caution may be necessary during concomitant use of cetirizine/levocetirizine with the antimuscarinics.
    Chlophedianol; Dexchlorpheniramine; Pseudoephedrine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Chloral Hydrate: (Moderate) CNS depression can be increased when mepenzolate is combined with other CNS depressants such as any anxiolytics, sedatives, and hypnotics.
    Chlorcyclizine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Chlorpheniramine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Chlorpheniramine; Codeine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when codeine is used concomitantly with an anticholinergic drug. The concomitant use of codeine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect. (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Chlorpheniramine; Dextromethorphan: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Chlorpheniramine; Dextromethorphan; Phenylephrine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Chlorpheniramine; Dihydrocodeine; Phenylephrine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when dihydrocodeine is used concomitantly with an anticholinergic drug. The concomitant use of dihydrocodeine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect. (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Chlorpheniramine; Dihydrocodeine; Pseudoephedrine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when dihydrocodeine is used concomitantly with an anticholinergic drug. The concomitant use of dihydrocodeine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect. (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Chlorpheniramine; Guaifenesin; Hydrocodone; Pseudoephedrine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when hydrocodone is used concomitantly with an anticholinergic drug. The concomitant use of hydrocodone and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect. (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Chlorpheniramine; Hydrocodone: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when hydrocodone is used concomitantly with an anticholinergic drug. The concomitant use of hydrocodone and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect. (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Chlorpheniramine; Hydrocodone; Phenylephrine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when hydrocodone is used concomitantly with an anticholinergic drug. The concomitant use of hydrocodone and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect. (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Chlorpheniramine; Hydrocodone; Pseudoephedrine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when hydrocodone is used concomitantly with an anticholinergic drug. The concomitant use of hydrocodone and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect. (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Chlorpheniramine; Phenylephrine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Chlorpheniramine; Pseudoephedrine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Chlorpromazine: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including chlorpromazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
    Cholinergic agonists: (Major) The muscarinic actions of drugs known as parasympathomimetics, including both direct cholinergic receptor agonists and cholinesterase inhibitors, can antagonize the antimuscarinic actions of anticholinergic drugs, and vice versa.
    Ciclesonide: (Minor) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Cisapride: (Moderate) The use of drugs that decrease GI motility, such as drugs that exert antimuscarinic properties may pharmacodynamically oppose the effects of cisapride.
    Cisatracurium: (Moderate) CNS depression can be increased when mepenzolate is combined with other CNS depressants such as neuromuscular blockers.
    Clemastine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Clozapine: (Moderate) Clozapine exhibits significant anticholinergic effects that may be enhanced when combined with antimuscarinics such as mepenzolate.
    Codeine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when codeine is used concomitantly with an anticholinergic drug. The concomitant use of codeine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Codeine; Guaifenesin: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when codeine is used concomitantly with an anticholinergic drug. The concomitant use of codeine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Codeine; Phenylephrine; Promethazine: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including promethazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur. (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when codeine is used concomitantly with an anticholinergic drug. The concomitant use of codeine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Codeine; Promethazine: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including promethazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur. (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when codeine is used concomitantly with an anticholinergic drug. The concomitant use of codeine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Corticosteroids: (Minor) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Corticotropin, ACTH: (Minor) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Cortisone: (Minor) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Crofelemer: (Moderate) Pharmacodynamic interactions between crofelemer and antimuscarinics are theoretically possible. Crofelemer does not affect GI motility mechanisms, but does have antidiarrheal effects. Patients taking medications that decrease GI motility, such as antimuscarinics, may be at greater risk for serious complications from crofelemer, such as constipation with chronic use. Use caution and monitor GI symptoms during coadministration.
    Cyclizine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Cyclobenzaprine: (Moderate) Depending on the specific agent, additive anticholinergic effects may be seen when drugs with antimuscarinic properties like cyclobenzaprine are used concomitantly with other anticholinergics. Clinicians should note that additive antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the CNS, the eye, and temperature regulation. Additive drowsiness may also occur, depending on the interacting agent.
    Cyproheptadine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Dantrolene: (Moderate) CNS depression can be increased when mepenzolate is combined with other CNS depressants such as skeletal muscle relaxants.
    Deflazacort: (Minor) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Dexamethasone: (Minor) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Dexchlorpheniramine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Dexchlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Dextromethorphan; Diphenhydramine; Phenylephrine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Dextromethorphan; Promethazine: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including promethazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
    Dextromethorphan; Quinidine: (Moderate) The reduction in GI motility produced by mepenzolate may increase the absorption of some drugs, including quinidine. Increased monitoring is advised in patients receiving this combination.
    Diazepam: (Moderate) CNS depression can be increased when mepenzolate is combined with other CNS depressants such as skeletal muscle relaxants.
    Digoxin: (Moderate) Oral formulations of digoxin can produce higher serum concentrations when administered concurrently with antimuscarinics, such as mepenzolate, because of decreased GI motility induced by the antimuscarinic agent. This interaction has mostly occurred in the literature with slowly-dissolving, large-particle formulations of digoxin tablets; the manufacture of oral digoxin products today, utilizing liquid formulations and/or smaller particle sizes, theoretically reduces the potential for absorption interactions. However, there is wide variability expected in individual responses to many digoxin-drug interactions. Other pharmacodynamic and pharmacokinetic systemic interactions are possible between digoxin and select antimuscarinic agents. Anticholinergics, because of their ability to cause tachycardia, can also antagonize the beneficial actions of digoxin in atrial fibrillation/flutter. Routine therapeutic monitoring should be continued when an antimuscarinic agent is prescribed with digoxin until the effects of combined use are known.
    Dihydrocodeine; Guaifenesin; Pseudoephedrine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when dihydrocodeine is used concomitantly with an anticholinergic drug. The concomitant use of dihydrocodeine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Dimenhydrinate: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Diphenhydramine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Diphenhydramine; Hydrocodone; Phenylephrine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when hydrocodone is used concomitantly with an anticholinergic drug. The concomitant use of hydrocodone and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect. (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Diphenhydramine; Ibuprofen: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Diphenhydramine; Naproxen: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Diphenhydramine; Phenylephrine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Disopyramide: (Moderate) In addition to its electrophysiologic effects, disopyramide exhibits clinically significant anticholinergic properties. These can be additive with other anticholinergics. Clinicians should be aware that urinary retention, particularly in males, and aggravation of glaucoma are realistic possibilities of using disopyramide with other anticholinergic agents.
    Donepezil: (Moderate) The therapeutic benefits of donepezil, a cholinesterase inhibitor, may be diminished during chronic co-administration with antimuscarinics or medications with potent anticholinergic activity. When concurrent use is not avoidable, the patient should be monitored for cognitive decline and anticholinergic side effects. Clinicians should generally avoid multiple medications with anticholinergic activity in the patient with dementia. Some of the common selective antimuscarinic drugs for bladder problems, (such as oxybutynin, darifenacin, trospium, fesoterodine, tolerodine, or solifenacin), do not routinely cause problems with medications used for dementia, but may cause anticholinergic side effects in some patients. Atropine may be used to offset bradycardia in cholinesterase inhibitor overdose.
    Donepezil; Memantine: (Moderate) The adverse effects of anticholinergics, such as dry mouth, urinary hesitancy or blurred vision may be enhanced with use of memantine; dosage adjustments of the anticholinergic drug may be required when memantine is coadministered. In addition, preliminary evidence indicates that chronic anticholinergic use in patients with Alzheimer's Disease may possibly have an adverse effect on cognitive function. Therefore, the effectiveness of drugs used in the treatment of Alzheimer's such as memantine, may be adversely affected by chronic antimuscarinic therapy. (Moderate) The therapeutic benefits of donepezil, a cholinesterase inhibitor, may be diminished during chronic co-administration with antimuscarinics or medications with potent anticholinergic activity. When concurrent use is not avoidable, the patient should be monitored for cognitive decline and anticholinergic side effects. Clinicians should generally avoid multiple medications with anticholinergic activity in the patient with dementia. Some of the common selective antimuscarinic drugs for bladder problems, (such as oxybutynin, darifenacin, trospium, fesoterodine, tolerodine, or solifenacin), do not routinely cause problems with medications used for dementia, but may cause anticholinergic side effects in some patients. Atropine may be used to offset bradycardia in cholinesterase inhibitor overdose.
    Doxacurium: (Moderate) CNS depression can be increased when mepenzolate is combined with other CNS depressants such as neuromuscular blockers.
    Doxylamine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Doxylamine; Pyridoxine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Dronabinol, THC: (Moderate) Use caution if coadministration of dronabinol with anticholinergics is necessary. Concurrent use of dronabinol, THC with anticholinergics may result in additive drowsiness, hypertension, tachycardia, and possibly cardiotoxicity.
    Eluxadoline: (Major) Avoid use of eluxadoline with medications that may cause constipation, such as anticholinergics. Discontinue use of eluxadoline in patients who develop severe constipation lasting more than 4 days.
    Epinephrine: (Moderate) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Erythromycin: (Moderate) Anticholinergics can antagonize the stimulatory effects of erythromycin on the GI tract (when erythromycin is used therapeutically for improving GI motility). Avoid chronic administration of antimuscarinics along with prokinetic agents under most circumstances. In addition, erythromycin is a CYP3A4 inhibitor and can reduce the metabolism of drugs metabolized by CYP3A4, including some anticholinergics.
    Erythromycin; Sulfisoxazole: (Moderate) Anticholinergics can antagonize the stimulatory effects of erythromycin on the GI tract (when erythromycin is used therapeutically for improving GI motility). Avoid chronic administration of antimuscarinics along with prokinetic agents under most circumstances. In addition, erythromycin is a CYP3A4 inhibitor and can reduce the metabolism of drugs metabolized by CYP3A4, including some anticholinergics.
    Eszopiclone: (Moderate) CNS depression can be increased when mepenzolate is combined with other CNS depressants such as any anxiolytics, sedatives, and hypnotics.
    Ethanol: (Moderate) CNS depression can be increased when mepenzolate is combined with other CNS depressants such as ethanol.
    Ezogabine: (Moderate) Caution is advisable during concurrent use of ezogabine and medications that may affect voiding such as anticholinergic agents. Ezogabine has caused urinary retention requiring catheterization in some cases. The anticholinergic effects of antimuscariinic and anticholinergic medications on the urinary tract may be additive. Additive sedation or other CNS effects may also occur.
    Fentanyl: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when fentanyl is used concomitantly with an anticholinergic drug. The concomitant use of fentanyl and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Fludrocortisone: (Minor) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Flunisolide: (Minor) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Fluoxetine; Olanzapine: (Moderate) Olanzapine exhibits anticholinergic effects that may be enhanced when combined with other with anticholinergic activity including the mepenzolate. Clinicians should note that additive antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the CNS, the eye, and temperature regulation. Additive drowsiness may also occur.
    Fluphenazine: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including fluphenazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
    Fluticasone: (Minor) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Fluticasone; Salmeterol: (Minor) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Fluticasone; Umeclidinium; Vilanterol: (Moderate) There is the potential for umeclidinium to have additive anticholinergic effects when administered with other anticholinergics or antimuscarinics. Per the manufaturer, avoid concomitant administration of umeclidinium with other anticholinergic medications when possible. (Minor) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Fluticasone; Vilanterol: (Minor) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Formoterol; Mometasone: (Minor) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Galantamine: (Moderate) The therapeutic benefits of galantamine, a cholinesterase inhibitor, may be diminished during chronic co-administration with antimuscarinics or medications with potent anticholinergic activity. When concurrent use is not avoidable, the patient should be monitored for cognitive decline and anticholinergic side effects. Clinicians should generally avoid multiple medications with anticholinergic activity in the patient with dementia. Some of the common selective antimuscarinic drugs for bladder problems, (such as oxybutynin, darifenacin, trospium, fesoterodine, tolerodine, or solifenacin), do not routinely cause problems with medications used for dementia, but may cause anticholinergic side effects in some patients. Atropine may be used to offset bradycardia in cholinesterase inhibitor overdose.
    Glucagon: (Major) The concomitant use of intravenous glucagon and anticholinergics increases the risk of gastrointestinal adverse reactions due to additive effects on inhibition of gastrointestinal motility. Concomitant use is not recommended.
    Guaifenesin; Hydrocodone: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when hydrocodone is used concomitantly with an anticholinergic drug. The concomitant use of hydrocodone and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Guaifenesin; Hydrocodone; Pseudoephedrine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when hydrocodone is used concomitantly with an anticholinergic drug. The concomitant use of hydrocodone and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Homatropine; Hydrocodone: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when hydrocodone is used concomitantly with an anticholinergic drug. The concomitant use of hydrocodone and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Hydralazine; Isosorbide Dinitrate, ISDN: (Moderate) Additive anticholinergic effects may be seen when mepenzolate is used concomitantly with nitrates. Clinicians should note that antimuscarinic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur.
    Hydrocodone: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when hydrocodone is used concomitantly with an anticholinergic drug. The concomitant use of hydrocodone and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Hydrocodone; Ibuprofen: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when hydrocodone is used concomitantly with an anticholinergic drug. The concomitant use of hydrocodone and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Hydrocodone; Phenylephrine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when hydrocodone is used concomitantly with an anticholinergic drug. The concomitant use of hydrocodone and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Hydrocodone; Potassium Guaiacolsulfonate: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when hydrocodone is used concomitantly with an anticholinergic drug. The concomitant use of hydrocodone and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Hydrocodone; Potassium Guaiacolsulfonate; Pseudoephedrine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when hydrocodone is used concomitantly with an anticholinergic drug. The concomitant use of hydrocodone and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Hydrocodone; Pseudoephedrine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when hydrocodone is used concomitantly with an anticholinergic drug. The concomitant use of hydrocodone and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Hydrocortisone: (Minor) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Hydromorphone: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when hydromorphone is used concomitantly with an anticholinergic drug. The concomitant use of hydromorphone and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Hydroxyzine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Ibuprofen; Oxycodone: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when oxycodone is used concomitantly with an anticholinergic drug. The concomitant use of oxycodone and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Ipratropium: (Moderate) Although ipratropium is minimally absorbed into the systemic circulation after inhalation, there is the potential for tiotropium to have additive anticholinergic effects when administered with other antimuscarinics. Per the manufaturer, avoid concomitant administration of ipratropium with other anticholinergic medications, such as antimucarinics.
    Isosorbide Dinitrate, ISDN: (Moderate) Additive anticholinergic effects may be seen when mepenzolate is used concomitantly with nitrates. Clinicians should note that antimuscarinic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur.
    Isosorbide Mononitrate: (Moderate) Additive anticholinergic effects may be seen when mepenzolate is used concomitantly with nitrates. Clinicians should note that antimuscarinic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur.
    Itraconazole: (Moderate) Antimuscarinics can raise intragastric pH. This effect may decrease the oral bioavailability of itraconazole; antimuscarinics should be used cautiously in patients receiving itraconazole.
    Ketoconazole: (Moderate) Antimuscarinic drugs can raise intragastric pH. Since ketoconazole requires an acidic environment for absorption, the bioavailability of ketoconazole may be reduced when combined with mepenzolate.
    Levocetirizine: (Moderate) Dry mouth and drowsiness were more common in patients receiving cetirizine/levocetirizine vs. placebo, and caution may be necessary during concomitant use of cetirizine/levocetirizine with the antimuscarinics.
    Levorphanol: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when levorphanol is used concomitantly with an anticholinergic drug. The concomitant use of levorphanol and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Linaclotide: (Moderate) Anticholinergics can promote constipation and pharmacodynamically oppose the action of drugs used for the treatment of constipation, such as linaclotide. The clinical significance of these potential interactions is uncertain.
    Loxapine: (Moderate) Additive anticholinergic effects may be seen when mepenzolate is used concomitantly with loxapine. Clinicians should note that antimuscarinic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur.
    Lubiprostone: (Moderate) Antimuscarinic drugs can promote constipation and pharmacodynamically oppose the action of drugs used for the treatment of constipation, such as lubiprostone. The clinical significance of these potential interactions is uncertain.
    Lurasidone: (Moderate) Antipsychotic agents may disrupt core temperature regulation; therefore, caution is recommended during concurrent use of lurasidone and medications with anticholinergic activity such as antimuscarinics. Concurrent use of lurasidone and medications with anticholinergic activity may contribute to heat-related disorders. Monitor patients for heat intolerance, decreased sweating, or increased body temperature if lurasidone is used with antimuscarinics.
    Magnesium Hydroxide: (Moderate) Antacids may inhibit the oral absorption of anticholinergics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Maprotiline: (Moderate) Additive anticholinergic and CNS effects may be seen when maprotiline is used concomitantly with mepenzolate.
    Meclizine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Memantine: (Moderate) The adverse effects of anticholinergics, such as dry mouth, urinary hesitancy or blurred vision may be enhanced with use of memantine; dosage adjustments of the anticholinergic drug may be required when memantine is coadministered. In addition, preliminary evidence indicates that chronic anticholinergic use in patients with Alzheimer's Disease may possibly have an adverse effect on cognitive function. Therefore, the effectiveness of drugs used in the treatment of Alzheimer's such as memantine, may be adversely affected by chronic antimuscarinic therapy.
    Meperidine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when meperidine is used concomitantly with an anticholinergic drug. The concomitant use of meperidine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Meperidine; Promethazine: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including promethazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur. (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when meperidine is used concomitantly with an anticholinergic drug. The concomitant use of meperidine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Meprobamate: (Moderate) CNS depression can be increased when mepenzolate is combined with other CNS depressants such as any anxiolytics, sedatives, and hypnotics.
    Metaxalone: (Moderate) CNS depression can be increased when mepenzolate is combined with other CNS depressants such as skeletal muscle relaxants.
    Methadone: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when methadone is used concomitantly with an anticholinergic drug. The concomitant use of methadone and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Methocarbamol: (Moderate) CNS depression can be increased when mepenzolate is combined with other CNS depressants such as skeletal muscle relaxants.
    Methylprednisolone: (Minor) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Metoclopramide: (Moderate) Drugs with significant antimuscarinic activity, such as anticholinergics and antimuscarinics, may slow GI motility and thus may reduce the prokinetic actions of metoclopramide. Monitor patients for an increase in gastrointestinal complaints, such as reflux or constipation. Additive drowsiness may occur as well. The clinical significance is uncertain.
    Mirtazapine: (Moderate) Mirtazapine exhibits weak anticholinergic activity that is not expected to be clinically significant. However, the anticholinergic effects may be additive to the antimuscarinics. Clinicians should note that additive antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the CNS, the eye, and temperature regulation.
    Mivacurium: (Moderate) CNS depression can be increased when mepenzolate is combined with other CNS depressants such as neuromuscular blockers.
    Molindone: (Moderate) Antipsychotics are associated with anticholinergic effects; therefore, additive effects may be seen during concurrent use of molindone and other drugs having anticholinergic activity such as antimuscarinics. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other CNS effects may also occur.
    Mometasone: (Minor) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Morphine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Morphine; Naltrexone: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when morphine is used concomitantly with an anticholinergic drug. The concomitant use of morphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Nabilone: (Moderate) Concurrent use of nabilone with anticholinergics may result in pronounced tachycardia and drowsiness.
    Nalbuphine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when nalbuphine is used concomitantly with an anticholinergic drug. The concomitant use of nalbuphine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Neuromuscular blockers: (Moderate) CNS depression can be increased when mepenzolate is combined with other CNS depressants such as neuromuscular blockers.
    Nitrates: (Moderate) Additive anticholinergic effects may be seen when mepenzolate is used concomitantly with nitrates. Clinicians should note that antimuscarinic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur.
    Nitrofurantoin: (Moderate) Antimuscarinics can delay gastric emptying, possibly increasing the bioavailability of nitrofurantoin.
    Nitroglycerin: (Moderate) Additive anticholinergic effects may be seen when mepenzolate is used concomitantly with nitrates. Clinicians should note that antimuscarinic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur.
    Olanzapine: (Moderate) Olanzapine exhibits anticholinergic effects that may be enhanced when combined with other with anticholinergic activity including the mepenzolate. Clinicians should note that additive antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the CNS, the eye, and temperature regulation. Additive drowsiness may also occur.
    Omeprazole; Sodium Bicarbonate: (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Orphenadrine: (Moderate) Additive anticholinergic effects may be seen when orphenadrine is used concomitantly with other antimuscarinics.
    Oxycodone: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when oxycodone is used concomitantly with an anticholinergic drug. The concomitant use of oxycodone and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Oxymorphone: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when oxymorphone is used concomitantly with an anticholinergic drug. The concomitant use of oxymorphone and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Pancuronium: (Moderate) CNS depression can be increased when mepenzolate is combined with other CNS depressants such as neuromuscular blockers.
    Pentazocine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when pentazocine is used concomitantly with an anticholinergic drug. The concomitant use of pentazocine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Pentazocine; Naloxone: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when pentazocine is used concomitantly with an anticholinergic drug. The concomitant use of pentazocine and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Perphenazine: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including perphenazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
    Perphenazine; Amitriptyline: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including perphenazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
    Phentermine; Topiramate: (Moderate) Use caution if carbonic anhydrase inhibitors are administered with anticholinergics and monitor for excessive anticholinergic adverse effects. The use of topiramate with agents that may increase the risk for heat-related disorders, such as anticholinergics, may lead to oligohidrosis, hyperthermia and/or heat stroke.
    Phenylephrine; Promethazine: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including promethazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
    Potassium: (Major) Drugs that decrease GI motility may increase the risk of GI irritation from sustained-release solid oral dosage forms of potassium salts. The use of solid oral dosage forms of potassium chloride is contraindicated in patients taking glycopyrrolate oral solution. In one study, healthy subjects were examined for GI irritation following the administration of oral potassium for at least 7 days. Glycopyrrolate was coadministered to some subjects in order to study the additional effects of delayed gastric emptying. Results indicated that subjects administered wax-matrix tablets had the highest incidence of erosions (43%) and ulcers (11%). Evidence of GI irritation was less frequent among subjects receiving liquid (0%) and microencapsulated (10.5% erosions, 1.2% ulcers) formulations. Therefore, if oral potassium supplementation is necessary in a patient taking antimuscarinics, a liquid formulation should be considered. If a solid formulation is being prescribed, the patient should be counseled on strategies that can be used to avoid GI irritation such as taking potassium products only while seated or standing, remaining upright for 10 minutes after each dose, and ingesting each dose with plenty of fluids.
    Pramlintide: (Major) Pramlintide therapy should not be considered in patients taking medications that alter gastric motility, such as anticholinergics. Pramlintide slows gastric emptying and the rate of nutrient delivery to the small intestine. Medications that have depressive effects on GI could potentiate the actions of pramlintide.
    Prednisolone: (Minor) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Prednisone: (Minor) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Prilocaine; Epinephrine: (Moderate) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Procainamide: (Moderate) The anticholinergic effects of procainamide may be significant and may be enhanced when combined with anticholinergics. Anticholinergic agents administered concurrently with procainamide may produce additive antivagal effects on AV nodal conduction, although this is not as well documented for procainamide as for quinidine.
    Prochlorperazine: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including prochlorperazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
    Promethazine: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including promethazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
    Proton pump inhibitors: (Moderate) The American College of Gastroenterology states that the effectiveness of proton pump inhibitors (PPIs) may be theoretically decreased if given with other antisecretory agents (e.g., anticholinergics). Proton pump inhibitors (PPIs) inhibit only actively secreting H+-pumps.
    Quinidine: (Moderate) The reduction in GI motility produced by mepenzolate may increase the absorption of some drugs, including quinidine. Increased monitoring is advised in patients receiving this combination.
    Rapacuronium: (Moderate) CNS depression can be increased when mepenzolate is combined with other CNS depressants such as neuromuscular blockers.
    Rasagiline: (Moderate) MAOIs exhibit secondary anticholinergic actions. Additive anticholinergic effects may be seen when MAOIs are used concomitantly with antimuscarinics. Clinicians should note that antimuscarinic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive CNS effects are also possible when many of these drugs are combined with MAOIs.
    Remifentanil: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when remifentanil is used concomitantly with an anticholinergic drug. The concomitant use of remifentanil and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Rivastigmine: (Moderate) The therapeutic benefits of rivastigmine, a cholinesterase inhibitor, may be diminished during chronic co-administration with antimuscarinics or medications with potent anticholinergic activity. When concurrent use is not avoidable, the patient should be monitored for cognitive decline and anticholinergic side effects. Clinicians should generally avoid multiple medications with anticholinergic activity in the patient with dementia. Some of the common selective antimuscarinic drugs for bladder problems, (such as oxybutynin, darifenacin, trospium, fesoterodine, tolerodine, or solifenacin), do not routinely cause problems with medications used for dementia, but may cause anticholinergic side effects in some patients. Atropine may be used to offset bradycardia in cholinesterase inhibitor overdose.
    Rocuronium: (Moderate) CNS depression can be increased when mepenzolate is combined with other CNS depressants such as neuromuscular blockers.
    Secretin: (Major) Discontinue anticholinergic medications at least 5 half-lives before administering secretin. Patients who are receiving anticholinergics at the time of stimulation testing may be hyporesponsive to secretin stimulation and produce a false result. Consider additional testing and clinical assessments for aid in diagnosis.
    Sedating H1-blockers: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Sincalide: (Moderate) Sincalide-induced gallbladder ejection fraction may be affected by anticholinergics. False study results are possible in patients with drug-induced hyper- or hypo-responsiveness; thorough patient history is important in the interpretation of procedure results.
    Sodium Bicarbonate: (Moderate) Antacids may inhibit the oral absorption of antimuscarinics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
    Solifenacin: (Moderate) Additive anticholinergic effects may be seen when drugs with antimuscarinic properties like solifenacin are used concomitantly with other antimuscarinics. Blurred vision and dry mouth would be common effects. Clinicians should note that additive antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the CNS, the eye, and temperature regulation. Additive drowsiness may also occur.
    Succinylcholine: (Moderate) CNS depression can be increased when mepenzolate is combined with other CNS depressants such as neuromuscular blockers.
    Sufentanil: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when sufentanil is used concomitantly with an anticholinergic drug. The concomitant use of sufentanil and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Tacrine: (Moderate) The therapeutic benefits of tacrine, a cholinesterase inhibitor, may be diminished during chronic co-administration with antimuscarinics or medications with potent anticholinergic activity. When concurrent use is not avoidable, the patient should be monitored for cognitive decline and anticholinergic side effects. Clinicians should generally avoid multiple medications with anticholinergic activity in the patient with dementia. Some of the common selective antimuscarinic drugs for bladder problems, (such as oxybutynin, darifenacin, trospium, fesoterodine, tolerodine, or solifenacin), do not routinely cause problems with medications used for dementia, but may cause anticholinergic side effects in some patients. Atropine may be used to offset bradycardia in cholinesterase inhibitor overdose.
    Tapentadol: (Moderate) Tapentadol should be used cautiously with anticholinergic medications since additive depressive effects on GI motility or bladder function may occur. Monitor patients for signs of urinary retention or reduced gastric motility. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect. Opiate analgesics combined with antimuscarinics can cause severe constipation or paralytic ileus, especially with chronic use. Additive CNS effects like drowsiness or dizziness may also occur.
    Tegaserod: (Major) Drugs that exert significant anticholinergic properties such as antimuscarinics may pharmacodynamically oppose the effects of prokinetic agents such as tegaserod. Avoid administering antimuscarinics along with tegaserod under most circumstances. Inhaled respiratory antimuscarinics, such as ipratropium, are unlikely to interact with tegaserod. Ophthalmic anticholinergics may interact if sufficient systemic absorption of the eye medication occurs.
    Thiazide diuretics: (Minor) Coadministration of thiazides and antimuscarinics (e.g., atropine and biperiden) may result in increased bioavailability of the thiazide. This is apparently a result of a decrease in gastrointestinal motility and rate of stomach emptying by the antimuscarinic agent. In addition, diuretics can increase urinary frequency, which may aggravate bladder symptoms.
    Thiothixene: (Moderate) Anticholinergics may have additive effects with thiothixene, an antipsychotic with the potential for anticholinergic activity. Monitor for anticholinergic-related adverse effects such as xerostomia, blurred vision, constipation, and urinary retention during concurrent use.
    Tiotropium: (Moderate) Although tiotropium is minimally absorbed into the systemic circulation after inhalation, tiotropium may have additive anticholinergic effects when administered with other antimuscarinics. Per the manufacturer, avoid concomitant administration of tiotropium with other anticholinergic medications when possible.
    Tiotropium; Olodaterol: (Moderate) Although tiotropium is minimally absorbed into the systemic circulation after inhalation, tiotropium may have additive anticholinergic effects when administered with other antimuscarinics. Per the manufacturer, avoid concomitant administration of tiotropium with other anticholinergic medications when possible.
    Tizanidine: (Moderate) CNS depression can be increased when mepenzolate is combined with other CNS depressants such as skeletal muscle relaxants.
    Tolterodine: (Moderate) Additive anticholinergic effects may be seen when tolterodine is used concomitantly with other antimuscarinics. When possible, avoid concurrent use, especially in the elderly, who are more susceptible to the anticholinergic effects. Consider alternatives to these other medications, if available. Clinicians should note that antimuscarinic effects might be seen not only on bladder smooth muscle, but also on GI function, the eye, and temperature regulation. Blurred vision, constipation, and dry mouth may be more prominent additive effects. With many of the listed agents, additive drowsiness may also occur when combined.
    Topiramate: (Moderate) Use caution if carbonic anhydrase inhibitors are administered with anticholinergics and monitor for excessive anticholinergic adverse effects. The use of topiramate with agents that may increase the risk for heat-related disorders, such as anticholinergics, may lead to oligohidrosis, hyperthermia and/or heat stroke.
    Tramadol: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when tramadol is used concomitantly with an anticholinergic drug. The concomitant use of tramadol and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Triamcinolone: (Minor) Anticholinergics, such as mepenzolate, antagonize the effects of antiglaucoma agents. Mepenzolate is contraindicated in patients with glaucoma and therefore should not be coadministered with medications being prescribed for the treatment of glaucoma. In addition, anticholinergic drugs taken concurrently with corticosteroids in the presence of increased intraocular pressure may be hazardous.
    Tricyclic antidepressants: (Moderate) Depending on the specific agent, additive anticholinergic effects may be seen when tricyclic antidepressants (TCAs) are used concomitantly with other anticholinergics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive CNS effects are also possible when many of these drugs are combined with tricyclic antidepressants.
    Trifluoperazine: (Moderate) Additive anticholinergic effects may be seen when anticholinergics are used concomitantly with phenothiazines, including trifluoperazine. Clinicians should note that antimuscarinic effects may be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness or other additive CNS effects may also occur.
    Trimethobenzamide: (Moderate) Trimethobenzamide has CNS depressant effects and may cause drowsiness. The concurrent use of trimethobenzamide with other medications that cause CNS depression, like the anticholinergics, may potentiate the effects of either trimethobenzamide or the anticholinergic.
    Triprolidine: (Moderate) The anticholinergic effects of sedating H1-blockers may be enhanced when combined with other antimuscarinics. Clinicians should note that anticholinergic effects might be seen not only on GI smooth muscle, but also on bladder function, the eye, and temperature regulation. Additive drowsiness may also occur when antimuscarinics are combined with sedating antihistamines.
    Trospium: (Moderate) Additive anticholinergic effects may be seen when trospium is used concomitantly with other antimuscarinics. When possible, avoid concurrent use, especially in the elderly, who are more susceptible to the anticholinergic effects. Consider alternatives to these other medications, if available. Clinicians should note that antimuscarinic effects might be seen not only on bladder smooth muscle, but also on GI function, the eye, and temperature regulation. Blurred vision, constipation, and dry mouth may be more prominent additive effects. With many of the listed agents, additive drowsiness may also occur when combined with trospium.
    Tubocurarine: (Moderate) CNS depression can be increased when mepenzolate is combined with other CNS depressants such as neuromuscular blockers.
    Umeclidinium: (Moderate) There is the potential for umeclidinium to have additive anticholinergic effects when administered with other anticholinergics or antimuscarinics. Per the manufaturer, avoid concomitant administration of umeclidinium with other anticholinergic medications when possible.
    Umeclidinium; Vilanterol: (Moderate) There is the potential for umeclidinium to have additive anticholinergic effects when administered with other anticholinergics or antimuscarinics. Per the manufaturer, avoid concomitant administration of umeclidinium with other anticholinergic medications when possible.
    Vecuronium: (Moderate) CNS depression can be increased when mepenzolate is combined with other CNS depressants such as neuromuscular blockers.
    Zaleplon: (Moderate) CNS depression can be increased when mepenzolate is combined with other CNS depressants such as any anxiolytics, sedatives, and hypnotics.
    Zolpidem: (Moderate) CNS depression can be increased when mepenzolate is combined with other CNS depressants such as any anxiolytics, sedatives, and hypnotics.
    Zonisamide: (Moderate) Zonisamide use is associated with case reports of decreased sweating, hyperthermia, heat intolerance, or heat stroke and should be used with caution in combination with other drugs that may also predispose patients to heat-related disorders like anticholinergics.

    PREGNANCY AND LACTATION

    Pregnancy

    Mepenzolate is classified as FDA pregnancy risk category B. Animal studies show no evidence of fetal harm. However, no adequate and well-controlled studies with mepenzolate in pregnant women exist. In one large prospective study, 2323 patients were exposed to mepenzolate and other drugs within the same class during the first trimester of pregnancy; only 1 patient was exposed to mepenzolate. A possible association between the total treatment group and minor malformations was found. Therefore, in making the decision to administer this drug during pregnancy, the potential risks to the fetus must be weighed against the potential benefits to the mother.

    According to the manufacturer, it is not known whether mepenzolate is excreted in human milk and therefore caution should be exercised when mepenzolate is administered during breast-feeding. Similar to other drugs with anticholinergic properties, mepenzolate may theoretically suppress lactation. In addition, neonates and infants are usually more sensitive to the anticholinergic effects of drugs. Consider the benefits of breast-feeding, the risk of potential infant drug exposure, and the risk of an untreated or inadequately treated condition. If a breast-feeding infant experiences an adverse effect related to a maternally ingested drug, healthcare providers are encouraged to report the adverse effect to the FDA.

    MECHANISM OF ACTION

    Mepenzolate is a quaternary ammonium anticholinergic compound. Like other anticholinergic (antimuscarinic) agents, it inhibits the action of acetylcholine on structures innervated by postganglionic cholinergic nerves and on smooth muscles that respond to acetylcholine by lack cholinergic innervation. In the gastrointestinal tract, mepenzolate diminishes gastric acid and pepsin secretion and suppresses spontaneous contractions of the colon. Similar to other quaternary ammonium anticholinergics, mepenzolate has limited ability to cross lipid membranes, such as the blood-brain barrier.

    PHARMACOKINETICS

    Mepenzolate is administered orally. Between 3% and 22% of a radiolabeled dose is excreted in the urine over a 5-day period; the majority of the radioactivity appears on day 1, and the remainder appears in the feces on days 2—5 as unabsorbed drug.

    Oral Route

    Because mepenzolate is a quaternary compound and is ionized after oral administration, its absorption is low. The low oral absorption of the drug has been confirmed via animal and human studies using radiolabeled mepenzolate.