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  • CLASSES

    Antivertigo Products
    Mydriatics and Cycloplegics

    DEA CLASS

    Rx

    DESCRIPTION

    Antimuscarinic
    Less potent than atropine on the heart and on bronchial and GI smooth muscle, but more potent on the iris, ciliary body, and bronchial, salivary, and sweat glands
    Produces CNS depression and paradoxical CNS excitation

    COMMON BRAND NAMES

    Transderm Scop

    HOW SUPPLIED

    Scopolamine/Scopolamine Hydrobromide Intramuscular Inj Sol: 0.4mg, 1mL
    Scopolamine/Scopolamine Hydrobromide Intravenous Inj Sol: 0.4mg, 1mL
    Scopolamine/Scopolamine Hydrobromide Subcutaneous Inj Sol: 0.4mg, 1mL
    Scopolamine/Transderm Scop Transdermal Film ER: 1mg, 72h

    DOSAGE & INDICATIONS

    For the treatment of nausea/vomiting.
    Subcutaneous dosage
    Adults

    0.6 to 1 mg subcutaneously.

    Children

    0.006 mg/kg (6 mcg/kg) subcutaneously.

    For nausea/vomiting prophylaxis due to motion sickness.
    Transdermal dosage
    Adults

    Apply one patch (delivers approximately 1 mg over 3 days) to a hairless area of the skin behind the ear at least 4 hours before antiemetic effects are needed. The patch may be left in place for 3 days. If therapy is needed for more than 3 days, remove the first patch, and apply a new patch to the hairless area of the skin behind the opposite ear.

    For use in aspiration prophylaxis prior to anesthesia and intubation; for treatment of bradycardia during surgery.
    Subcutaneous, Intravenous, or Intramuscular dosage
    Adults

    The recommended dose is 0.3 to 0.6 mg subcutaneously, IM, or IV as a single dose 45 to 60 minutes before induction of anesthesia.

    Children 1 to 12 years

    The recommended dose is 0.006 mg/kg subcutaneously, IM, or IV as a single dose. Do not exceed 0.3 mg per dose.

    For obstetric amnesia induction.
    Intramuscular, Intravenous, or Subcutaneous dosage
    Adults

    The recommended dose is 0.32 to 0.65 mg IM, IV, or subcutaneously.

    For procedural sedation.
    Intramuscular, Intravenous, or Subcutaneous dosage
    Adults, Adolescents, and Children 7 years and older

    0.32 to 0.65 mg IM, IV, or subcutaneously.

    Children 3 to 6 years

    0.2 to 0.3 mg IM, IV, or subcutaneously.

    Children 3 years and younger and Infants 6 months and older

    0.1 to 0.15 mg IM, IV, or subcutaneously.

    For use as a sedative or tranquilizer for sedation induction.
    Intramuscular, Intravenous, or Subcutaneous dosage
    Adults

    0.6 mg IM, IV, or subcutaneously 3 to 4 times per day.

    For the adjunct treatment of alcohol withdrawal (i.e., delirium tremens).
    Intravenous, Intramuscular, or Subcutaneous Dosage
    Adults

    Administer 0.6 mg IM, IV, or subcutaneously. Not commonly employed in modern treatment protocols; historic medical use.

    For the treatment of mania.
    Intramuscular, Intravenous, or Subcutaneous dosage
    Adults

    0.6 mg IM, IV, or subcutaneously.

    For cycloplegia induction or mydriasis induction during ophthalmologic examination.
    Ophthalmic dosage
    Adults

    Instill 1 to 2 drops of 0.25% solution in eye(s) 1 hour before refraction.

    Children

    Instill 1 drop of 0.25% solution in eye(s) 1 hour before refraction.

    For the treatment of iritis or uveitis.
    Ophthalmic dosage
    Adults

    Instill 1 to 2 drops of 0.25% solution in affected eye(s) up to 4 times daily.

    Children

    Instill 1 drop of 0.25% solution in affected eye(s) once, twice, or 3 times daily.

    For the treatment of sialorrhea†.
    Transdermal dosage
    Adults

    1.5 mg transdermal scopolamine was found beneficial in a series of over 100 patients in the treatment of sialorrhea associated with parotidectomies and tracheotomies, drainage of peritonsillar abscesses, tonsillitis, pharyngitis, neurologic disorders (unspecified), cerebral palsy, mental retardation, idiopathic drooling, and during the perioperative period. Three patients received a dosage of 2 patches (3 mg transdermally), although no conclusion was made by the authors regarding a difference in efficacy compared to the 1.5 mg dosage. Treatment effectiveness was measured by subject reports of dryness of the mouth. The reduction in salivary flow ranged from 43% to 100% among the groups. The mean time of scopolamine treatment ranged from 1 to 7 days. Three patients developed urinary retention, and seven patients developed blurred vision.

    Children greater than 5 years and weighing more than 15 kg

    1.5 mg transdermal scopolamine was compared to placebo in a cross-over study of 11 developmentally delayed children with moderate to severe drooling. Each treatment was used for 2 weeks with a 1 week washout period. The transdermal patches were changed twice weekly. Ten subjects completed the study. One subject withdrew due to extreme dizziness and falling during the placebo phase. Significantly less drooling occurred in over half of the subjects with the scopolamine patch compared to placebo, and one-third had cessation of drooling with scopolamine.

    †Indicates off-label use

    MAXIMUM DOSAGE

    Adults

    2.4 mg/day subcutaneously/IM/IV; 8 drops/eye/day; one patch transdermally every 3 days.

    Geriatric

    2.4 mg/day subcutaneously/IM/IV; 8 drops/eye/day; one patch transdermally every 3 days.

    Adolescents

    0.6 mg/dose subcutaneously/IM/IV; 3 drops/eye/day.

    Children

    7 years and older: 0.6 mg/dose subcutaneously/IM/IV; 3 drops/eye/day.
    3 to 6 years: 0.3 mg/dose subcutaneously/IM/IV. 3 drops/eye/day.
    1 to 2 years: 0.15 mg/dose subcutaneously/IM/IV. 3 drops/eye/day.

    Infants

    6 months and older: 0.15 mg/dose subcutaneously/IM/IV. 3 drops/eye/day.

    DOSING CONSIDERATIONS

    Hepatic Impairment

    Specific guidelines for dosage adjustments in hepatic impairment are not available; however, scopolamine should be used with caution due to an increased risk of CNS adverse effects.

    Renal Impairment

    Specific guidelines for dosage adjustments in renal impairment are not available; however, scopolamine should be used with caution due to an increased risk of CNS adverse effects.

    ADMINISTRATION

    Injectable Administration

    May be administered subcutaneously, intramuscularly, or intravenously.
    Visually inspect parenteral products for particulate matter and discoloration prior to administration whenever solution and container permit.

    Intravenous Administration

    Direct IV injection:
    Dilute scopolamine with an equal volume of sterile water for injection prior to administration.
    Inject slowly IV over 2—3 minutes.

    Intramuscular Administration

    Inject scopolamine into a large muscle. Aspirate prior to injection to avoid injection into a blood vessel.

    Subcutaneous Administration

    Inject scopolamine subcutaneously taking care not to inject intradermally.

    Topical Administration

    Instruct patient on the proper use and application of the transdermal patch.
    Wash hands after application.
    Apply scopolamine patch at least 4 hours prior to anticipated exposure to motion.

    Ophthalmic Administration

    For ophthalmic use only. Instruct patient on proper instillation of ophthalmic solution.
    To avoid systemic absorption of scopolamine , instruct patient to apply pressure to the lacrimal sac for 1—2 minutes after instillation.
    Do not to touch the tip of the dropper or tube to the eye, fingertips, or other surface.

    STORAGE

    Generic:
    - Protect from light
    - Store at controlled room temperature (between 68 and 77 degrees F)
    Maldemar:
    - Store at room temperature (between 59 to 86 degrees F)
    Scopace:
    - Store at room temperature (between 59 to 86 degrees F)
    Transderm Scop:
    - Store at controlled room temperature (between 68 and 77 degrees F)

    CONTRAINDICATIONS / PRECAUTIONS

    General Information

    Patients with a known hypersensitivity to belladonna alkaloids can experience an allergic reaction including anaphylaxis with scopolamine.

    Anticholinergic medications

    The anticholinergic effects of scopolamine may be significant and are additive with other anticholinergic medications. This is especially true for the older adult, but may also occur with any patient. Consider the anticholinergic burden of all applicable medication therapies and consider the potential for additive side effects.

    Closed-angle glaucoma, contact lenses, open-angle glaucoma

    Scopolamine is contraindicated in patients with closed-angle glaucoma because the drug can induce cycloplegia and mydriasis, which would result in increased intraocular pressure. Scopolamine should be avoided in open-angle glaucoma. The anticholinergic effects of scopolamine may make the eyes dry. This can cause an increased lens awareness, or blurred vision for wearers of contact lenses. The use of lubricating drops may be necessary, or in severe cases discontinued use of contact lenses while using scopolamine skin patches.

    Prostatic hypertrophy, urinary tract obstruction

    Scopolamine use should be avoided in patients with urinary tract obstruction or bladder neck obstruction due to prostatic hypertrophy because it can cause urinary retention via its antimuscarinic effects on the ureters and bladder.

    Gastroesophageal reflux disease (GERD), GI obstruction, hiatal hernia, ileus, toxic megacolon, ulcerative colitis

    Scopolamine should be avoided in patients with GI obstruction because its antimotility effects can exacerbate this disease state and can cause paralytic ileus. Scopolamine is not recommended for use in patients with severe ulcerative colitis because it decreases GI motility and can exacerbate the condition. Scopolamine is not recommended for use in patients with adynamic ileus, and toxic megacolon because it further decreases intestinal motility and exacerbates these conditions. Scopolamine should be used cautiously in patients with gastroesophageal reflux disease (GERD) or hiatal hernia associated with reflux esophagitis. Antimuscarinics decrease gastric motility and relax the lower esophageal sphincter. These effects promote gastric retention and aggravate reflux in these patients.

    Asthma, chronic obstructive pulmonary disease (COPD)

    Scopolamine should be used with caution in patients with asthma or chronic obstructive pulmonary disease (COPD) because of its effects on bronchial smooth muscle and bronchial secretory glands.

    Autonomic neuropathy, myasthenia gravis

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

    Cardiac arrhythmias, coronary artery disease, heart failure, hypertension, hyperthyroidism

    Scopolamine should be avoided in patients with coronary artery disease or congestive heart failure because it can increase heart rate, which would increase the oxygen demand on the heart. Scopolamine should be used with caution in patients with hyperthyroidism because these patients may be at an increased risk of suffering adverse effects, especially in the heart. Scopolamine should be used with caution in patients with hypertension since the drug has some actions on the heart and can exacerbate this condition. Scopolamine is not recommended for use in patients with cardiac arrhythmias because it can potentiate arrhythmias by blocking the vagal inhibition of the SA node.

    Hepatic disease

    Scopolamine should be used with caution in patients with hepatic disease because the drug can accumulate to toxic levels in the body.

    Renal impairment

    Scopolamine should be used with caution in patients with renal impairment because of an increased likelihood of CNS adverse effects.

    Pregnancy

    Scopolamine is classified as FDA pregnancy risk category C; routine use during pregnancy, with the exception of use around cesarean section, should be avoided when possible. Scopolamine does cross the placenta. Scopolamine hydrobromide has been shown to have a marginal embryotoxic effect in rabbits when administered by daily intravenous injection at doses producing plasma levels approximately 100 times the level achieved in humans using a transdermal system. Scopolamine has been used in obstetric settings as part of premedication and anesthesia regimens. Scopolamine administered parenterally at higher doses than the dose delivered by transdermal systems does not increase the duration of labor, nor does it affect uterine contractions. During a clinical study among women undergoing cesarean section treated with scopolamine transdermal patches (Transderm Scop) in conjunction with epidural anesthesia and opiate analgesia, no evidence of CNS depression was found in the newborns. Other than in the adjunctive use for delivery by cesarean section, scopolamine should be used in pregnancy only if the potential benefit justifies the potential risk to the fetus.

    Breast-feeding

    Scopolamine is excreted in human milk. The manufacturer warns that caution should be exercised when administering scopolamine to a breast-feeding woman, particularly with extended therapy, such as with transdermal patch administration. Drugs with anticholinergic properties, such as scopolamine, may suppress lactation, particularly when lactation is starting to be established. There are no controlled data regarding effect on the nursing infant; however, the infant, like other pediatric patients, would be more susceptible to any anticholinergic effects. However, single doses, such as those that may be used perioperatively or brief ophthalmic drop administration, may be unlikely to cause concern during lactation. In contrast to manufacturer labels, the American Academy of Pediatrics considers scopolamine to be generally compatible with breast-feeding. 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.

    Geriatric

    Geriatric patients may be more sensitive to the effects of scopolamine. The anticholinergic effects of scopolamine may be significant and are additive with other anticholinergic medications, particularly in the older adult. According to the Beers Criteria, anti-spasmodics such as scopolamine (excluding ophthalmic) are considered potentially inappropriate medications (PIMs) for use in geriatric patients and should be avoided in this population due to uncertain effectiveness and high anticholinergic activity. The Beers expert panel also recommends avoiding drugs with strong anticholinergic properties, such as scopolamine, in geriatric patients with the following disease states or symptoms due to the potential for exacerbation of the condition or increased risk of adverse effects: dementia/cognitive impairment (adverse CNS effects), delirium/high risk of delirium (possible new-onset or worsening delirium), or lower urinary tract symptoms/benign prostatic hyperplasia in men (possible urinary retention or hesitancy). The federal Omnibus Budget Reconciliation Act (OBRA) regulates medication use in residents of long-term care facilities (LTCFs). According to the OBRA guidelines, medications with anticholinergic properties, such as scopolamine, may cause mental status changes, constipation, drowsiness, dizziness, dryness of mucus membranes, blurred vision, urinary retention, or other adverse effects that are common and problematic, especially in older individuals. The use of multiple medications with anticholinergic properties may be particularly problematic because of cumulative effects.

    Magnetic resonance imaging (MRI)

    Skin burns have been reported at the patch site in several patients wearing an aluminized transdermal system during a magnetic resonance imaging (MRI) scan. Because the Transderm Scop patch contains aluminum, it is recommended to remove the system before undergoing an MRI.

    Children, infants, neonates

    Children, including neonates and infants, are particularly susceptible to the side effects of belladonna alkaloids like scopolamine. The safety and effectiveness of transdermal scopolamine in children has not been established; the patch should not be used in children because it is not known whether this system will release an amount of scopolamine that could produce serious adverse effects in adolescents, children, infants and neonates.

    ADVERSE REACTIONS

    Severe

    bradycardia / Rapid / Incidence not known

    Moderate

    confusion / Early / Incidence not known
    hallucinations / Early / Incidence not known
    delirium / Early / Incidence not known
    memory impairment / Delayed / Incidence not known
    amnesia / Delayed / Incidence not known
    orthostatic hypotension / Delayed / Incidence not known
    sinus tachycardia / Rapid / Incidence not known
    palpitations / Early / Incidence not known
    anhidrosis / Delayed / Incidence not known
    heat intolerance / Early / Incidence not known
    constipation / Delayed / Incidence not known
    dysphagia / Delayed / Incidence not known
    urinary retention / Early / Incidence not known
    contact dermatitis / Delayed / Incidence not known
    erythema / Early / Incidence not known
    photophobia / Early / Incidence not known
    cycloplegia / Early / Incidence not known
    conjunctivitis / Delayed / Incidence not known
    blurred vision / Early / Incidence not known

    Mild

    xerostomia / Early / 67.0-67.0
    drowsiness / Early / 17.0-17.0
    restlessness / Early / Incidence not known
    fatigue / Early / Incidence not known
    headache / Early / Incidence not known
    dizziness / Early / Incidence not known
    tremor / Early / Incidence not known
    fever / Early / Incidence not known
    flushing / Rapid / Incidence not known
    urticaria / Rapid / Incidence not known
    nausea / Early / Incidence not known
    vomiting / Early / Incidence not known
    pyrosis (heartburn) / Early / Incidence not known
    blepharedema / Early / Incidence not known
    rash (unspecified) / Early / Incidence not known
    xerophthalmia / Early / Incidence not known
    mydriasis / Early / Incidence not known

    DRUG INTERACTIONS

    Abatacept: (Minor) Because abatacept has been shown to potentiate the onset of respiratory infections, concomitant use of drugs that decrease mucociliary clearance should be used cautiously. Anticholinergics, such as scopolamine, have been shown to be capable of depressing the mucociliary transport system.
    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: (Major) Additive anticholinergic effects may be seen when scopolamine is used concomitantly with other antimuscarinics, such as amantadine. 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.
    Ambenonium Chloride: (Major) The muscarinic actions of ambenonium chloride can antagonize the antimuscarinic actions of scopolamine.
    Aminoglycosides: (Minor) Antiemetics, like scopolamine, should be used carefully with amikacin because they can mask symptoms of ototoxicity (e.g., nausea secondary to vertigo). These agents block the histamine or acetylcholine response that causes nausea due to vestibular (inner ear) emetic stimuli such as motion.
    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.
    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) Scopolamine may cause dizziness and drowsiness. Concurrent use of scopolamine and CNS depressants can adversely increase the risk of CNS depression.
    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; 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; 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) Scopolamine and atomoxetine should be combined cautiously in patients with known cardiac disease. Scopolamine 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.
    Atropine; Edrophonium: (Major) The muscarinic actions of edrophonium chloride can antagonize the antimuscarinic actions of scopolamine.
    Barbiturates: (Moderate) Scopolamine may cause dizziness and drowsiness. Concurrent use of scopolamine and CNS depressants can adversely increase the risk of CNS depression.
    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.
    Benzodiazepines: (Moderate) Scopolamine may cause dizziness and drowsiness. Concurrent use of scopolamine and CNS depressants can adversely increase the risk of CNS depression.
    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).
    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.
    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 scopolamine 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 scopolamine 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.
    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.
    Carbidopa; Levodopa: (Minor) The doses of antimuscarinics and levodopa may need to be adjusted when the drugs are given simultaneously. Through central antimuscarinic actions, anticholinergics can potentiate the dopaminergic effects of levodopa. While some patients may benefit from this interaction, clinicians should be ready to decrease doses of levodopa if an antimuscarinic is added.
    Carbidopa; Levodopa; Entacapone: (Minor) The doses of antimuscarinics and levodopa may need to be adjusted when the drugs are given simultaneously. Through central antimuscarinic actions, anticholinergics can potentiate the dopaminergic effects of levodopa. While some patients may benefit from this interaction, clinicians should be ready to decrease doses of levodopa if an antimuscarinic is added.
    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.
    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.
    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.
    Cisapride: (Moderate) The use of drugs that decrease GI motility, such as scopolamine, may pharmacodynamically oppose the effects of cisapride.
    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) Additive anticholinergic effects may be seen when scopolamine is used concomitantly with other drugs with moderate to significant anticholinergic effects including clozapine.
    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.
    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.
    Deutetrabenazine: (Moderate) Concurrent use of deutetrabenazine and drugs that can cause CNS depression, such as scopolamine, may have additive effects and worsen drowsiness or sedation. Advise patients about worsened somnolence and not to drive or perform other tasks requiring mental alertness until they know how deutetrabenazine affects them.
    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 scopolamine may increase the absorption of some drugs, including quinidine, resulting in increased anticholinergic effects. Increased monitoring is advised in patients receiving this combination.
    Digoxin: (Moderate) Anticholinergics, because of their ability to cause tachycardia, can 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.
    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.
    Droperidol: (Moderate) Scopolamine may cause dizziness and drowsiness. Concurrent use of scopolamine and CNS depressants can adversely increase the risk of CNS depression.
    Edrophonium: (Major) The muscarinic actions of edrophonium chloride can antagonize the antimuscarinic actions of scopolamine.
    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.
    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.
    Ethanol: (Moderate) Scopolamine may cause dizziness and drowsiness. Concurrent use of scopolamine and CNS depressants can adversely increase the risk of CNS depression.
    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.
    Fluoxetine; Olanzapine: (Moderate) Additive anticholinergic effects may be seen when scopolamine is used concomitantly with other commonly used drugs with moderate to significant anticholinergic effects including olanzapine. 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.
    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; 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.
    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.
    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.
    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.
    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.
    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.
    Levodopa: (Minor) The doses of antimuscarinics and levodopa may need to be adjusted when the drugs are given simultaneously. Through central antimuscarinic actions, anticholinergics can potentiate the dopaminergic effects of levodopa. While some patients may benefit from this interaction, clinicians should be ready to decrease doses of levodopa if an antimuscarinic is added.
    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.
    Loperamide: (Moderate) Loperamide decreases GI motility. Agents that inhibit intestinal motility or prolong intestinal transit time have been reported to induce toxic megacolon. Other drugs that also decrease GI motility may produce additive effects with loperamide if used concomitantly. These include therapeutic doses of common systemic antimuscarinics (e.g., scopolamine). Additive GI and CNS actions and may lead to undesirable side effects in some patients.
    Loperamide; Simethicone: (Moderate) Loperamide decreases GI motility. Agents that inhibit intestinal motility or prolong intestinal transit time have been reported to induce toxic megacolon. Other drugs that also decrease GI motility may produce additive effects with loperamide if used concomitantly. These include therapeutic doses of common systemic antimuscarinics (e.g., scopolamine). Additive GI and CNS actions and may lead to undesirable side effects in some patients.
    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 effects may be seen when scopolamine is used concomitantly with other drugs with moderate to significant anticholinergic effects including maprotiline. 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.
    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.
    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.
    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.
    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.
    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.
    Neostigmine: (Major) The muscarinic actions of neostigmine can antagonize the antimuscarinic actions of scopolamine.
    Nitrofurantoin: (Moderate) Antimuscarinics can delay gastric emptying, possibly increasing the bioavailability of nitrofurantoin.
    Olanzapine: (Moderate) Additive anticholinergic effects may be seen when scopolamine is used concomitantly with other commonly used drugs with moderate to significant anticholinergic effects including olanzapine. 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.
    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 scopolamine is used concomitantly with other drugs with moderate to significant anticholinergic effects including orphenadrine.
    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.
    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.
    Physostigmine: (Major) The muscarinic actions of physostigmine can antagonize the antimuscarinic actions of scopolamine.
    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.
    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.
    Pyridostigmine: (Major) The muscarinic actions of pyridostigmine can antagonize the antimuscarinic actions of scopolamine.
    Quinidine: (Moderate) The reduction in GI motility produced by scopolamine may increase the absorption of some drugs, including quinidine, resulting in increased anticholinergic effects. Increased monitoring is advised in patients receiving this combination.
    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.
    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.
    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.
    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.
    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.
    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.
    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

    Scopolamine is classified as FDA pregnancy risk category C; routine use during pregnancy, with the exception of use around cesarean section, should be avoided when possible. Scopolamine does cross the placenta. Scopolamine hydrobromide has been shown to have a marginal embryotoxic effect in rabbits when administered by daily intravenous injection at doses producing plasma levels approximately 100 times the level achieved in humans using a transdermal system. Scopolamine has been used in obstetric settings as part of premedication and anesthesia regimens. Scopolamine administered parenterally at higher doses than the dose delivered by transdermal systems does not increase the duration of labor, nor does it affect uterine contractions. During a clinical study among women undergoing cesarean section treated with scopolamine transdermal patches (Transderm Scop) in conjunction with epidural anesthesia and opiate analgesia, no evidence of CNS depression was found in the newborns. Other than in the adjunctive use for delivery by cesarean section, scopolamine should be used in pregnancy only if the potential benefit justifies the potential risk to the fetus.

    Scopolamine is excreted in human milk. The manufacturer warns that caution should be exercised when administering scopolamine to a breast-feeding woman, particularly with extended therapy, such as with transdermal patch administration. Drugs with anticholinergic properties, such as scopolamine, may suppress lactation, particularly when lactation is starting to be established. There are no controlled data regarding effect on the nursing infant; however, the infant, like other pediatric patients, would be more susceptible to any anticholinergic effects. However, single doses, such as those that may be used perioperatively or brief ophthalmic drop administration, may be unlikely to cause concern during lactation. In contrast to manufacturer labels, the American Academy of Pediatrics considers scopolamine to be generally compatible with breast-feeding. 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

    Scopolamine antagonizes acetylcholine at muscarinic receptors (e.g., skin, GI tract, respiratory tract, heart, CNS, and the eye), although, in high doses, antagonism at nicotinic receptors (e.g., skeletal muscle, ganglia) can occur. Because scopolamine is a tertiary amine like atropine, it can cross into the CNS. Clinically, scopolamine is used to prevent nausea and vomiting associated with motion sickness, to reduce salivation and excess bronchial secretions prior to surgery, to reduce spastic states in parkinsonism, and to produce cycloplegic refraction and pupil dilation to treat pre- and postoperative iridocyclitis.
     
    As an antiemetic, scopolamine probably blocks neural pathways from the vestibular nuclei in the inner ear to the brain stem and from the reticular formation to the vomiting center. Because acetylcholine mediates impulses from the inner ear, scopolamine is an effective antiemetic in motion sickness. Scopolamine is a poor choice, however, for treating nausea/vomiting in other settings since neural pathways not mediated by acetylcholine are involved. High doses of scopolamine produce symptoms of antimuscarinic toxicity such as restlessness, disorientation, irritability, and hallucinations.
     
    Reduction of secretions occurs by competitive blockade of acetylcholine and other cholinergic stimuli at cholinergic receptor sites on salivary and bronchial glands. In the treatment of spastic states in parkinsonism, scopolamine blocks excess cholinergic activity in the basal ganglia. Antagonism of acetylcholine on the sphincter and ciliary body in the eye, produces mydriasis and cycloplegia.

    PHARMACOKINETICS

    Scopolamine is well absorbed after oral, topical, and intramuscular (IM) or subcutaneous (SC) administration.  After absorption, scopolamine is distributed throughout the body and crosses the placenta and the blood-brain barrier. The metabolism of scopolamine is not completely known, but the drug is believed to be almost completely metabolized in the liver and excreted renally as metabolites. The elimination half-life is about 8 hours.

    Oral Route

    The effects of scopolamine occur 15—30 minutes after oral administration.

    Intramuscular Route

    The effects of scopolamine occur 15—30 minutes after IM administration.

    Subcutaneous Route

    The effects of scopolamine occur 15—30 minutes after SC administration.