Ditropan XL

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Ditropan XL

Classes

Antimuscarinics

Administration
Oral Administration

May be administered on an empty stomach. To prevent gastric irritation, give with meals or milk.

Oral Solid Formulations

Extended release tablets:
Administer at roughly the same time each day.
Administer the ER tablet whole with a sip of liquid; do not crush, chew, or divide.
The biologically inert portions of the Ditropan XL tablet remain intact during intestinal transit and may be visible in the stool.

Oral Liquid Formulations

Oral solution or syrup:
Measure dosage with a calibrated oral dosage device to ensure accurate dosing.

Topical Administration Transdermal Patch Formulations

Transdermal Biweekly Patch delivering 3.9 mg/day oxybutynin (i.e., Oxytrol patch, Oxytrol for Women)
Apply to clean, dry skin on the abdomen, hip, or buttock. Avoid applying to areas with cuts, calluses, scars, oil, burns, or irritation.
Rotate application site. Remove old patch before applying a new patch. Avoiding re-application to the same site within 7 days.
Use firm pressure over patch for 10 seconds to ensure contact with skin, especially around the edges. If patch becomes loose or falls off, replace with another one. Do not cut or trim patch.
Patches should not be affected by showering or bathing.

Other Topical Formulations

Topical 10% Gel (i.e., Gelnique 10% gel)
Apply topically only. Do not ingest.
Apply to clean, dry skin on the abdomen, upper arms/shoulders, or thighs. If applying to the abdomen, avoid the navel. Also avoid applying to areas with cuts, calluses, scars, oil, burns, irritation or skin that has recently been shaven.
Rotate application site each day; avoid use of the same site on consecutive days.
Squeeze the entire contents of 1 packet sachet or 1 actuation of the metered-dose pump into the palm of the hand or directly onto the application site. Gently rub the gel into the skin until it is dried. After applying, wash hands with soap and water right away.
For 1 hour after application, the patient should avoid bathing, swimming, showering, exercising or immersing the application site in water. Allow the site to dry a few minutes before putting on clothing.
The gel may be used with sunscreen.
Advise the patient that the gel is flammable; avoid fire, flame, and smoking until the gel has dried.
If direct skin-to-skin contact with another person is expected, the application site should be covered with clothing once the gel has dried. If someone else is exposed to the gel or the application area, that person should wash the area of contact with soap and water as soon as possible.

Adverse Reactions
Severe

bronchospasm / Rapid / 1.0-4.9
keratoconjunctivitis / Early / 1.0-4.9
anaphylactoid reactions / Rapid / Incidence not known
angioedema / Rapid / Incidence not known
seizures / Delayed / Incidence not known
arrhythmia exacerbation / Early / Incidence not known
ocular hypertension / Delayed / Incidence not known
visual impairment / Early / Incidence not known

Moderate

constipation / Delayed / 1.3-15.1
blurred vision / Early / 1.0-9.6
erythema / Early / 3.7-8.3
urinary retention / Early / 1.2-6.0
dysphagia / Delayed / 1.0-4.9
confusion / Early / 1.0-4.9
flank pain / Delayed / 1.0-4.9
cystitis / Delayed / 1.0-4.9
dysuria / Early / 1.0-4.9
palpitations / Early / 1.0-4.9
peripheral edema / Delayed / 1.0-4.9
edema / Delayed / 1.0-4.9
sinus tachycardia / Rapid / 1.0-4.9
fluid retention / Delayed / 1.0-4.9
hyperglycemia / Delayed / 1.0-4.9
contact dermatitis / Delayed / 1.8-1.8
dysphonia / Delayed / 0-1.0
anhidrosis / Delayed / Incidence not known
ataxia / Delayed / Incidence not known
psychosis / Early / Incidence not known
memory impairment / Delayed / Incidence not known
nystagmus / Delayed / Incidence not known
hallucinations / Early / Incidence not known
delirium / Early / Incidence not known
impotence (erectile dysfunction) / Delayed / Incidence not known
hypertension / Early / Incidence not known
QT prolongation / Rapid / Incidence not known
chest pain (unspecified) / Early / Incidence not known
cycloplegia / Early / Incidence not known
lactation suppression / Early / Incidence not known

Mild

xerostomia / Early / 4.1-71.4
dizziness / Early / 2.8-16.6
drowsiness / Early / 5.6-14.0
nausea / Early / 4.5-11.6
diarrhea / Early / 1.0-7.9
headache / Early / 1.5-7.5
skin irritation / Early / 1.0-6.4
dyspepsia / Early / 4.5-6.0
insomnia / Early / 3.0-5.5
infection / Delayed / 1.0-5.4
vomiting / Early / 1.0-4.9
abdominal pain / Early / 1.0-4.9
eructation / Early / 1.0-4.9
flatulence / Early / 1.0-4.9
urticaria / Rapid / 1.0-4.9
pruritus / Rapid / 1.0-4.9
xerosis / Delayed / 1.0-4.9
cough / Delayed / 1.0-4.9
hoarseness / Early / 1.0-4.9
nasal dryness / Early / 1.0-4.9
pharyngitis / Delayed / 1.0-4.9
nasal congestion / Early / 1.0-4.9
flushing / Rapid / 1.0-4.9
fatigue / Early / 1.0-4.9
dysgeusia / Early / 1.0-4.9
asthenia / Delayed / 1.0-4.9
back pain / Delayed / 1.0-4.9
arthralgia / Delayed / 1.0-4.9
increased urinary frequency / Early / 1.0-4.9
ocular irritation / Rapid / 1.0-4.9
rash / Early / 3.3-3.3
vesicular rash / Delayed / 3.2-3.2
xerophthalmia / Early / 1.0-3.1
maculopapular rash / Early / 2.5-2.5
anorexia / Delayed / 0-1.0
gastroesophageal reflux / Delayed / 1.0-1.0
polydipsia / Early / 0-1.0
fever / Early / Incidence not known
rhinitis / Early / Incidence not known
agitation / Early / Incidence not known
mydriasis / Early / Incidence not known
ocular pain / Early / Incidence not known

Common Brand Names

Ditropan, Ditropan XL, Gelnique, Oxytrol, Oxytrol for Women

Dea Class

Rx, OTC

Description

Antimuscarinic agent with some antispasmodic actions
Used for overactive bladder (OAB) with symptoms of urge urinary incontinence, urinary urgency, and frequency; also used in pediatric patients 6 years and older for neurogenic bladder
Oral, topical, and transdermal dosage forms are available

Dosage And Indications
For the treatment of overactive bladder (OAB) or neurogenic bladder with symptoms of urge urinary incontinence, urinary urgency, and urinary frequency. Oral dosage (immediate-release) Adults

5 mg PO 2 to 3 times daily. Max: 5 mg PO 4 times daily.

Older Adults

2.5 mg PO 2 to 3 times daily, initially. Usual dose: 5 mg PO 2 to 3 times daily. Max: 5 mg PO 4 times daily.

Children and Adolescents 6 to 17 years

5 mg PO twice daily. Max: 5 mg PO 3 times daily.

Children 1 to 5 years†

0.2 mg/kg/day PO in 3 divided doses, initially. Usual dose: 0.2 mg/kg/day to 0.4 mg/kg/day PO in 3 divided doses.

Oral dosage (extended-release) Adults

5 to 10 mg PO once daily, initially. May increase the dose by 5 mg/week based on clinical response and tolerability. Max: 30 mg/day.

Children and Adolescents 6 to 17 years

5 mg PO once daily, initially. May increase the dose by 5 mg/week based on clinical response and tolerability. Max: 20 mg/day.

Transdermal dosage (patch) Adults

3.9 mg/day patch topically twice weekly (every 3 to 4 days).

Children and Adolescents 4 to 17 years†

Further study is needed to establish safety and efficacy in pediatric patients; for use by prescription only. In an open pilot study, 35 children (mean age: 8 years, range: 4 to 16 years) with non-neuropathic (idiopathic) overactive bladder (OAB) received 1 patch (delivering 3.9 mg/day of oxybutynin) topically twice weekly (every 3 to 4 days) as per the marketed product instructions. Most (97%) patients reported good symptom response.

Topical dosage (10% gel)

NOTE: 1 g of gel contains 100 mg oxybutynin.

Adults

100 mg (1 sachet or 1 actuation) topically once daily.

Dosing Considerations
Hepatic Impairment

No specific recommendations are available; use with caution. Extended-release oxybutynin tablets have not been studied in patients with hepatic impairment.

Renal Impairment

Use with caution; no dosage adjustments appear necessary as less than 0.1% of a dosage is excreted unchanged in the urine; the active metabolite desethyloxybutynin is also excreted in the urine at less than 0.1%. Extended-release oxybutynin tablets have not been studied in patients with renal impairment.

Drug Interactions

Acetaminophen; Aspirin, ASA; Caffeine: (Minor) Consuming greater than 400 mg/day caffeine has been associated with the development of urinary incontinence. Caffeine may aggravate bladder symptoms, increase urine output, and counteract the effectiveness of drugs used to treat overactive bladder such as oxybutynin. Patients may wish to limit their intake of caffeinated drugs, dietary supplements (e.g., guarana), or beverages (e.g., green tea, other teas, coffee, colas).
Acetaminophen; Caffeine: (Minor) Consuming greater than 400 mg/day caffeine has been associated with the development of urinary incontinence. Caffeine may aggravate bladder symptoms, increase urine output, and counteract the effectiveness of drugs used to treat overactive bladder such as oxybutynin. Patients may wish to limit their intake of caffeinated drugs, dietary supplements (e.g., guarana), or beverages (e.g., green tea, other teas, coffee, colas).
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. (Minor) Consuming greater than 400 mg/day caffeine has been associated with the development of urinary incontinence. Caffeine may aggravate bladder symptoms, increase urine output, and counteract the effectiveness of drugs used to treat overactive bladder such as oxybutynin. Patients may wish to limit their intake of caffeinated drugs, dietary supplements (e.g., guarana), or beverages (e.g., green tea, other teas, coffee, colas).
Acetaminophen; Caffeine; Pyrilamine: (Minor) Consuming greater than 400 mg/day caffeine has been associated with the development of urinary incontinence. Caffeine may aggravate bladder symptoms, increase urine output, and counteract the effectiveness of drugs used to treat overactive bladder such as oxybutynin. Patients may wish to limit their intake of caffeinated drugs, dietary supplements (e.g., guarana), or beverages (e.g., green tea, other teas, coffee, colas).
Acetaminophen; Codeine: (Moderate) Monitor for signs of urinary retention or reduced gastric motility during concomitant codeine and oxybutynin use. Concomitant use may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.
Acetaminophen; Dichloralphenazone; Isometheptene: (Moderate) Additive CNS depression may occur when oxybutynin is used concomitantly with other CNS-depressant drugs, including anxiolytics, sedatives, and hypnotics.
Acetaminophen; Hydrocodone: (Moderate) Monitor for signs of urinary retention or reduced gastric motility during concomitant hydrocodone and oxybutynin use. Concomitant use may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.
Acetaminophen; Oxycodone: (Moderate) Monitor for signs of urinary retention or reduced gastric motility during concomitant oxycodone and oxybutynin use. Concomitant use may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.
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 manufacturer, avoid concomitant administration of aclidinium with other anticholinergic medications, when possible.
Aclidinium; Formoterol: (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 manufacturer, avoid concomitant administration of aclidinium with other anticholinergic medications, when possible.
Adagrasib: (Moderate) Monitor for an increase in oxybutynin-related adverse reactions if coadministration with adagrasib is necessary. Oxybutynin is a CYP3A substrate and adagrasib is a strong CYP3A inhibitor. Coadministration with another strong CYP3A inhibitor increased mean oxybutynin plasma concentrations by approximately 2-fold.
Alfentanil: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when alfentanil is used concomitantly with an anticholinergic drug. The concomitant use of alfentanil and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
Alosetron: (Major) Concomitant use of alosetron and anticholinergics, which can decrease GI motility, may seriously worsen constipation, leading to events such as GI obstuction, impaction, or paralytic ileus. Although specific recommendations are not available from the manufacturer, it would be prudent to avoid anticholinergics in patients taking alosetron.
Aluminum Hydroxide: (Moderate) Antacids may inhibit the oral absorption of anticholinergics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
Aluminum Hydroxide; Magnesium Carbonate: (Moderate) Antacids may inhibit the oral absorption of anticholinergics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
Aluminum Hydroxide; Magnesium Hydroxide: (Moderate) Antacids may inhibit the oral absorption of anticholinergics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
Aluminum Hydroxide; Magnesium Hydroxide; Simethicone: (Moderate) Antacids may inhibit the oral absorption of anticholinergics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
Aluminum Hydroxide; Magnesium Trisilicate: (Moderate) Antacids may inhibit the oral absorption of anticholinergics. Simultaneous oral administration should be avoided when feasible; separate dosing by at least 2 hours to limit an interaction.
Amantadine: (Moderate) Additive anticholinergic effects may be seen when oxybutynin is used concomitantly with drugs with moderate to significant anticholinergic effects such as amantadine. Clinicians should note that anticholinergic effects might be seen not only on bladder smooth muscle, but also on GI function, the eye, and temperature regulation. With many of the listed agents, additive drowsiness may also occur when combined with oxybutynin.
Amobarbital: (Moderate) Additive CNS depression may occur when oxybutynin is used concomitantly with other CNS-depressant drugs, including anxiolytics, sedatives, and hypnotics. In addition, because oxybutynin is metabolized by CYP3A4, administration with drugs that induce CYP3A4 (such as barbiturates) may reduce the serum concentration and effects of oxybutynin. Patients receiving these drugs concomitantly should be monitored for reduced efficacy.
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.
Amoxicillin; Clarithromycin; Omeprazole: (Moderate) Oxybutynin is metabolized by CYP3A4. Serum concentrations of oxybutynin may be increased when administered with inhibitors of the CYP3A4 enzyme system, including clarithromycin.
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.
Aprepitant, Fosaprepitant: (Moderate) Use caution if oxybutynin and aprepitant, fosaprepitant are used concurrently and monitor for an increase in oxybutynin-related adverse effects for several days after administration of a multi-day aprepitant regimen. Oxybutynin is a CYP3A4 substrate. Aprepitant, when administered as a 3-day oral regimen (125 mg/80 mg/80 mg), is a moderate CYP3A4 inhibitor and inducer and may increase plasma concentrations of oxybutynin. For example, a 5-day oral aprepitant regimen increased the AUC of another CYP3A4 substrate, midazolam (single dose), by 2.3-fold on day 1 and by 3.3-fold on day 5. After a 3-day oral aprepitant regimen, the AUC of midazolam (given on days 1, 4, 8, and 15) increased by 25% on day 4, and then decreased by 19% and 4% on days 8 and 15, respectively. As a single 125 mg or 40 mg oral dose, the inhibitory effect of aprepitant on CYP3A4 is weak, with the AUC of midazolam increased by 1.5-fold and 1.2-fold, respectively. After administration, fosaprepitant is rapidly converted to aprepitant and shares many of the same drug interactions. However, as a single 150 mg intravenous dose, fosaprepitant only weakly inhibits CYP3A4 for a duration of 2 days; there is no evidence of CYP3A4 induction. Fosaprepitant 150 mg IV as a single dose increased the AUC of midazolam (given on days 1 and 4) by approximately 1.8-fold on day 1; there was no effect on day 4. Less than a 2-fold increase in the midazolam AUC is not considered clinically important.
Aspirin, ASA; Butalbital; Caffeine: (Moderate) Additive CNS depression may occur when oxybutynin is used concomitantly with other CNS-depressant drugs, including anxiolytics, sedatives, and hypnotics. In addition, because oxybutynin is metabolized by CYP3A4, administration with drugs that induce CYP3A4 (such as barbiturates) may reduce the serum concentration and effects of oxybutynin. Patients receiving these drugs concomitantly should be monitored for reduced efficacy. (Minor) Consuming greater than 400 mg/day caffeine has been associated with the development of urinary incontinence. Caffeine may aggravate bladder symptoms, increase urine output, and counteract the effectiveness of drugs used to treat overactive bladder such as oxybutynin. Patients may wish to limit their intake of caffeinated drugs, dietary supplements (e.g., guarana), or beverages (e.g., green tea, other teas, coffee, colas).
Aspirin, ASA; Caffeine: (Minor) Consuming greater than 400 mg/day caffeine has been associated with the development of urinary incontinence. Caffeine may aggravate bladder symptoms, increase urine output, and counteract the effectiveness of drugs used to treat overactive bladder such as oxybutynin. Patients may wish to limit their intake of caffeinated drugs, dietary supplements (e.g., guarana), or beverages (e.g., green tea, other teas, coffee, colas).
Aspirin, ASA; Caffeine; Orphenadrine: (Moderate) Additive anticholinergic effects may be seen when oxybutynin is used concomitantly with other drugs that have moderate to significant anticholinergic effects, including orphenadrine. Clinicians should note that anticholinergic effects might be seen not only on bladder smooth muscle, but also on GI function, the eye, and temperature regulation. Additive drowsiness may also occur. (Minor) Consuming greater than 400 mg/day caffeine has been associated with the development of urinary incontinence. Caffeine may aggravate bladder symptoms, increase urine output, and counteract the effectiveness of drugs used to treat overactive bladder such as oxybutynin. Patients may wish to limit their intake of caffeinated drugs, dietary supplements (e.g., guarana), or beverages (e.g., green tea, other teas, coffee, colas).
Aspirin, ASA; Carisoprodol; Codeine: (Moderate) Monitor for signs of urinary retention or reduced gastric motility during concomitant codeine and oxybutynin use. Concomitant use may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.
Aspirin, ASA; Citric Acid; 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.
Aspirin, ASA; Oxycodone: (Moderate) Monitor for signs of urinary retention or reduced gastric motility during concomitant oxycodone and oxybutynin use. Concomitant use may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.
Atazanavir: (Moderate) Monitor for an increase in oxybutynin-related adverse reactions if coadministration with protease inhibitors is necessary. Oxybutynin is a CYP3A substrate and protease inhibitors are moderate to strong CYP3A inhibitors. Coadministration with another strong CYP3A inhibitor increased mean oxybutynin plasma concentrations by approximately 2-fold. Concomitant use with moderate CYP3A inhibitors may alter the mean pharmacokinetic parameters of oxybutynin, although the clinical relevance of these potential interactions is unknown.
Atazanavir; Cobicistat: (Moderate) Monitor for an increase in oxybutynin-related adverse reactions if coadministration with protease inhibitors is necessary. Oxybutynin is a CYP3A substrate and protease inhibitors are moderate to strong CYP3A inhibitors. Coadministration with another strong CYP3A inhibitor increased mean oxybutynin plasma concentrations by approximately 2-fold. Concomitant use with moderate CYP3A inhibitors may alter the mean pharmacokinetic parameters of oxybutynin, although the clinical relevance of these potential interactions is unknown. (Moderate) The plasma concentrations of oxybutynin may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as increased anticholinergic activity, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while oxybutynin is a CYP3A4 substrate.
Barbiturates: (Moderate) Additive CNS depression may occur when oxybutynin is used concomitantly with other CNS-depressant drugs, including anxiolytics, sedatives, and hypnotics. In addition, because oxybutynin is metabolized by CYP3A4, administration with drugs that induce CYP3A4 (such as barbiturates) may reduce the serum concentration and effects of oxybutynin. Patients receiving these drugs concomitantly should be monitored for reduced efficacy.
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.
Benzhydrocodone; Acetaminophen: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when benzhydrocodone is used concomitantly with an anticholinergic drug. The concomitant use of benzhydrocodone 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.
Berotralstat: (Moderate) Monitor for oxybutynin-related adverse reactions if coadministration with berotralstat is necessary. Oxybutynin is a CYP3A4 substrate and berotralstat is a moderate CYP3A inhibitor. Concomitant use with moderate CYP3A4 inhibitors may alter the mean pharmacokinetic parameters of oxybutynin, although the clinical relevance of these potential interactions is unknown.
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).
Buprenorphine: (Moderate) Monitor for signs of urinary retention or reduced gastric motility during concomitant buprenorphine and oxybutynin use. Concomitant use may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.
Buprenorphine; Naloxone: (Moderate) Monitor for signs of urinary retention or reduced gastric motility during concomitant buprenorphine and oxybutynin use. Concomitant use may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.
Butabarbital: (Moderate) Additive CNS depression may occur when oxybutynin is used concomitantly with other CNS-depressant drugs, including anxiolytics, sedatives, and hypnotics. In addition, because oxybutynin is metabolized by CYP3A4, administration with drugs that induce CYP3A4 (such as barbiturates) may reduce the serum concentration and effects of oxybutynin. Patients receiving these drugs concomitantly should be monitored for reduced efficacy.
Butalbital; Acetaminophen: (Moderate) Additive CNS depression may occur when oxybutynin is used concomitantly with other CNS-depressant drugs, including anxiolytics, sedatives, and hypnotics. In addition, because oxybutynin is metabolized by CYP3A4, administration with drugs that induce CYP3A4 (such as barbiturates) may reduce the serum concentration and effects of oxybutynin. Patients receiving these drugs concomitantly should be monitored for reduced efficacy.
Butalbital; Acetaminophen; Caffeine: (Moderate) Additive CNS depression may occur when oxybutynin is used concomitantly with other CNS-depressant drugs, including anxiolytics, sedatives, and hypnotics. In addition, because oxybutynin is metabolized by CYP3A4, administration with drugs that induce CYP3A4 (such as barbiturates) may reduce the serum concentration and effects of oxybutynin. Patients receiving these drugs concomitantly should be monitored for reduced efficacy. (Minor) Consuming greater than 400 mg/day caffeine has been associated with the development of urinary incontinence. Caffeine may aggravate bladder symptoms, increase urine output, and counteract the effectiveness of drugs used to treat overactive bladder such as oxybutynin. Patients may wish to limit their intake of caffeinated drugs, dietary supplements (e.g., guarana), or beverages (e.g., green tea, other teas, coffee, colas).
Butalbital; Acetaminophen; Caffeine; Codeine: (Moderate) Additive CNS depression may occur when oxybutynin is used concomitantly with other CNS-depressant drugs, including anxiolytics, sedatives, and hypnotics. In addition, because oxybutynin is metabolized by CYP3A4, administration with drugs that induce CYP3A4 (such as barbiturates) may reduce the serum concentration and effects of oxybutynin. Patients receiving these drugs concomitantly should be monitored for reduced efficacy. (Moderate) Monitor for signs of urinary retention or reduced gastric motility during concomitant codeine and oxybutynin use. Concomitant use may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. (Minor) Consuming greater than 400 mg/day caffeine has been associated with the development of urinary incontinence. Caffeine may aggravate bladder symptoms, increase urine output, and counteract the effectiveness of drugs used to treat overactive bladder such as oxybutynin. Patients may wish to limit their intake of caffeinated drugs, dietary supplements (e.g., guarana), or beverages (e.g., green tea, other teas, coffee, colas).
Butalbital; Aspirin; Caffeine; Codeine: (Moderate) Additive CNS depression may occur when oxybutynin is used concomitantly with other CNS-depressant drugs, including anxiolytics, sedatives, and hypnotics. In addition, because oxybutynin is metabolized by CYP3A4, administration with drugs that induce CYP3A4 (such as barbiturates) may reduce the serum concentration and effects of oxybutynin. Patients receiving these drugs concomitantly should be monitored for reduced efficacy. (Moderate) Monitor for signs of urinary retention or reduced gastric motility during concomitant codeine and oxybutynin use. Concomitant use may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. (Minor) Consuming greater than 400 mg/day caffeine has been associated with the development of urinary incontinence. Caffeine may aggravate bladder symptoms, increase urine output, and counteract the effectiveness of drugs used to treat overactive bladder such as oxybutynin. Patients may wish to limit their intake of caffeinated drugs, dietary supplements (e.g., guarana), or beverages (e.g., green tea, other teas, coffee, colas).
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.
Caffeine: (Minor) Consuming greater than 400 mg/day caffeine has been associated with the development of urinary incontinence. Caffeine may aggravate bladder symptoms and counteract the effectiveness of drugs used to treat overactive bladder such as oxybutynin. (Minor) Consuming greater than 400 mg/day caffeine has been associated with the development of urinary incontinence. Caffeine may aggravate bladder symptoms, increase urine output, and counteract the effectiveness of drugs used to treat overactive bladder such as oxybutynin. Patients may wish to limit their intake of caffeinated drugs, dietary supplements (e.g., guarana), or beverages (e.g., green tea, other teas, coffee, colas).
Caffeine; Sodium Benzoate: (Minor) Consuming greater than 400 mg/day caffeine has been associated with the development of urinary incontinence. Caffeine may aggravate bladder symptoms, increase urine output, and counteract the effectiveness of drugs used to treat overactive bladder such as oxybutynin. Patients may wish to limit their intake of caffeinated drugs, dietary supplements (e.g., guarana), or beverages (e.g., green tea, other teas, coffee, colas).
Calcium Carbonate: (Major) Avoid concomitant use of calcium carbonate and anticholinergics. Antacids may interfere with the absorption of anticholinergics.
Calcium Carbonate; Famotidine; Magnesium Hydroxide: (Major) Avoid concomitant use of calcium carbonate and anticholinergics. Antacids may interfere with the absorption of anticholinergics.
Calcium Carbonate; Magnesium Hydroxide: (Major) Avoid concomitant use of calcium carbonate and anticholinergics. Antacids may interfere with the absorption of anticholinergics.
Calcium Carbonate; Magnesium Hydroxide; Simethicone: (Major) Avoid concomitant use of calcium carbonate and anticholinergics. Antacids may interfere with the absorption of anticholinergics.
Calcium Carbonate; Simethicone: (Major) Avoid concomitant use of calcium carbonate and anticholinergics. Antacids may interfere with the absorption of anticholinergics.
Calcium; Vitamin D: (Major) Avoid concomitant use of calcium carbonate and anticholinergics. Antacids may interfere with the absorption of anticholinergics.
Carbamazepine: (Minor) Monitor for signs and symptoms of carbamazepine toxicity during concomitant oxybutynin use. In a single case report, concomitant use of oxybutynin with carbamazepine (and dantrolene) was associated with vomiting, drowsiness, confusion, unsteadiness, slurred speech and nystagmus, suggestive of carbamazepine toxicity.
Carbidopa; Levodopa: (Minor) Through central antimuscarinic actions, anticholinergics can potentiate the dopaminergic effects of levodopa. Antimuscarinics, by slowing GI transit, may also decrease levodopa bioavailability; however, this mechanism appears to be of modest clinical significance. Antimuscarinic agents targeted specifically for urinary incontinence may be less likely to produce pronounced effects on levodopa response than those with more pronounced systemic action.
Carbidopa; Levodopa; Entacapone: (Minor) Through central antimuscarinic actions, anticholinergics can potentiate the dopaminergic effects of levodopa. Antimuscarinics, by slowing GI transit, may also decrease levodopa bioavailability; however, this mechanism appears to be of modest clinical significance. Antimuscarinic agents targeted specifically for urinary incontinence may be less likely to produce pronounced effects on levodopa response than those with more pronounced systemic action.
Celecoxib; Tramadol: (Moderate) Monitor for signs of urinary retention or reduced gastric motility during concomitant tramadol and oxybutynin use. Concomitant use may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.
Ceritinib: (Moderate) Monitor for an increase in oxybutynin-related adverse reactions if coadministration with ceritinib is necessary. Oxybutynin is a CYP3A4 substrate and ceritinib is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased mean oxybutynin plasma concentrations by approximately 2-fold.
Cetirizine: (Moderate) Monitor for signs or symptoms of anticholinergic toxicity during concomitant cetirizine and oxybutynin use. Concomitant use may result in additive anticholinergic adverse effects.
Cetirizine; Pseudoephedrine: (Moderate) Monitor for signs or symptoms of anticholinergic toxicity during concomitant cetirizine and oxybutynin use. Concomitant use may result in additive anticholinergic adverse effects.
Chlorpheniramine; Codeine: (Moderate) Monitor for signs of urinary retention or reduced gastric motility during concomitant codeine and oxybutynin use. Concomitant use may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.
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.
Chlorpheniramine; Hydrocodone: (Moderate) Monitor for signs of urinary retention or reduced gastric motility during concomitant hydrocodone and oxybutynin use. Concomitant use may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.
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) Oxybutynin is an antimuscarinic that decreases GI motility; drugs that exert antimuscarinic properties may pharmacodynamically oppose the effects of prokinetic agents such as cisapride. The clinical significance of this interaction is unknown.
Clarithromycin: (Moderate) Oxybutynin is metabolized by CYP3A4. Serum concentrations of oxybutynin may be increased when administered with inhibitors of the CYP3A4 enzyme system, including clarithromycin.
Clozapine: (Major) Avoid co-prescribing clozapine with other anticholinergic medicines that can cause gastrointestinal hypomotility, due to a potential to increase serious constipation, ileus, and other potentially serious bowel conditions that may result in hospitalization. Clozapine exhibits potent anticholinergic effects. Additive anticholinergic effects may be seen when clozapine is used concomitantly with anticholinergic agents. Adverse 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 anticholinergic agent used.
Cobicistat: (Moderate) The plasma concentrations of oxybutynin may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as increased anticholinergic activity, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while oxybutynin is a CYP3A4 substrate.
Codeine: (Moderate) Monitor for signs of urinary retention or reduced gastric motility during concomitant codeine and oxybutynin use. Concomitant use may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.
Codeine; Guaifenesin: (Moderate) Monitor for signs of urinary retention or reduced gastric motility during concomitant codeine and oxybutynin use. Concomitant use may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.
Codeine; Guaifenesin; Pseudoephedrine: (Moderate) Monitor for signs of urinary retention or reduced gastric motility during concomitant codeine and oxybutynin use. Concomitant use may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.
Codeine; Phenylephrine; Promethazine: (Moderate) Monitor for signs of urinary retention or reduced gastric motility during concomitant codeine and oxybutynin use. Concomitant use may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. (Moderate) Monitor for signs or symptoms of anticholinergic toxicity during concomitant promethazine and oxybutynin use. Concomitant use may result in additive anticholinergic adverse effects.
Codeine; Promethazine: (Moderate) Monitor for signs of urinary retention or reduced gastric motility during concomitant codeine and oxybutynin use. Concomitant use may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. (Moderate) Monitor for signs or symptoms of anticholinergic toxicity during concomitant promethazine and oxybutynin use. Concomitant use may result in additive anticholinergic adverse effects.
Conivaptan: (Minor) Monitor for oxybutynin-related adverse reactions if coadministration with conivaptan is necessary. Oxybutynin is a CYP3A substrate and conivaptan is a moderate CYP3A inhibitor. Concomitant use with moderate CYP3A inhibitors may alter the mean pharmacokinetic parameters of oxybutynin, although the clinical relevance of these potential interactions is unknown.
Crizotinib: (Minor) Monitor for oxybutynin-related adverse reactions if coadministration with crizotinib is necessary. Oxybutynin is a CYP3A4 substrate and crizotinib is a moderate CYP3A inhibitor. Concomitant use with moderate CYP3A4 inhibitors may alter the mean pharmacokinetic parameters of oxybutynin, although the clinical relevance of these potential interactions is unknown. The manufacturer of oxybutynin recommends administering with caution.
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.
Cyclobenzaprine: (Moderate) Monitor for signs or symptoms of anticholinergic toxicity during concomitant cyclobenzaprine and oxybutynin use. Concomitant use may result in additive anticholinergic adverse effects.
Danazol: (Moderate) Oxybutynin is metabolized by CYP3A4. Serum concentrations of oxybutynin may be increased if coadministered with inhibitors of CYP3A4 including danazol. The manufacturer recommends that caution when oxybutynin is co-administered with CYP3A4 inhibitors.
Darunavir: (Moderate) Monitor for an increase in oxybutynin-related adverse reactions if coadministration with protease inhibitors is necessary. Oxybutynin is a CYP3A substrate and protease inhibitors are moderate to strong CYP3A inhibitors. Coadministration with another strong CYP3A inhibitor increased mean oxybutynin plasma concentrations by approximately 2-fold. Concomitant use with moderate CYP3A inhibitors may alter the mean pharmacokinetic parameters of oxybutynin, although the clinical relevance of these potential interactions is unknown.
Darunavir; Cobicistat: (Moderate) Monitor for an increase in oxybutynin-related adverse reactions if coadministration with protease inhibitors is necessary. Oxybutynin is a CYP3A substrate and protease inhibitors are moderate to strong CYP3A inhibitors. Coadministration with another strong CYP3A inhibitor increased mean oxybutynin plasma concentrations by approximately 2-fold. Concomitant use with moderate CYP3A inhibitors may alter the mean pharmacokinetic parameters of oxybutynin, although the clinical relevance of these potential interactions is unknown. (Moderate) The plasma concentrations of oxybutynin may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as increased anticholinergic activity, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while oxybutynin is a CYP3A4 substrate.
Darunavir; Cobicistat; Emtricitabine; Tenofovir alafenamide: (Moderate) Monitor for an increase in oxybutynin-related adverse reactions if coadministration with protease inhibitors is necessary. Oxybutynin is a CYP3A substrate and protease inhibitors are moderate to strong CYP3A inhibitors. Coadministration with another strong CYP3A inhibitor increased mean oxybutynin plasma concentrations by approximately 2-fold. Concomitant use with moderate CYP3A inhibitors may alter the mean pharmacokinetic parameters of oxybutynin, although the clinical relevance of these potential interactions is unknown. (Moderate) The plasma concentrations of oxybutynin may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as increased anticholinergic activity, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while oxybutynin is a CYP3A4 substrate.
Dasiglucagon: (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.
Delavirdine: (Moderate) Oxybutynin is metabolized by CYP3A4. Serum concentrations of oxybutynin may be increased if coadministered with inhibitors of CYP3A4 including delavirdine. The manufacturer recommends that caution when oxybutynin is co-administered with CYP3A4 inhibitors.
Desmopressin: (Major) Hyponatremia-induced convulsions have been rarely reported when oxybutynin and desmopressin are used concomitantly. Use these drugs together with caution, and monitor patients for signs and symptoms of hyponatremia.
Dextromethorphan; Quinidine: (Moderate) The anticholinergic effects of quinidine may be significant and may be enhanced when combined with antimuscarinics.
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.
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.
Dronabinol: (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.
Dronedarone: (Moderate) Dronedarone is metabolized by and is an inhibitor of CYP3A. Oxybutynin is a substrate for CYP3A4. The concomitant administration of dronedarone and CYP3A substrates may result in increased exposure of the substrate and should, therefore, be undertaken with caution.
Efavirenz: (Moderate) Oxybutynin is metabolized by CYP3A. Drugs that induce CYP3A, such as efavirenz, may cause decreased serum concentrations of oxybutynin. The clinical significance of such interactions is not known; however patients receiving oxybutynin with efavirenz or efavirenz-containing products (e.g., efavirenz; emtricitabine; tenofovir) concomitantly should be monitored for efficacy.
Efavirenz; Emtricitabine; Tenofovir Disoproxil Fumarate: (Moderate) Oxybutynin is metabolized by CYP3A. Drugs that induce CYP3A, such as efavirenz, may cause decreased serum concentrations of oxybutynin. The clinical significance of such interactions is not known; however patients receiving oxybutynin with efavirenz or efavirenz-containing products (e.g., efavirenz; emtricitabine; tenofovir) concomitantly should be monitored for efficacy.
Efavirenz; Lamivudine; Tenofovir Disoproxil Fumarate: (Moderate) Oxybutynin is metabolized by CYP3A. Drugs that induce CYP3A, such as efavirenz, may cause decreased serum concentrations of oxybutynin. The clinical significance of such interactions is not known; however patients receiving oxybutynin with efavirenz or efavirenz-containing products (e.g., efavirenz; emtricitabine; tenofovir) concomitantly should be monitored for efficacy.
Elbasvir; Grazoprevir: (Moderate) Administering oxybutynin with elbasvir; grazoprevir may result in elevated oxybutynin plasma concentrations. Oxybutynin is a substrate of CYP3A; grazoprevir is a weak CYP3A inhibitor. If these drugs are used together, closely monitor for signs of adverse events.
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.
Elvitegravir; Cobicistat; Emtricitabine; Tenofovir Alafenamide: (Moderate) The plasma concentrations of oxybutynin may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as increased anticholinergic activity, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while oxybutynin is a CYP3A4 substrate.
Elvitegravir; Cobicistat; Emtricitabine; Tenofovir Disoproxil Fumarate: (Moderate) The plasma concentrations of oxybutynin may be elevated when administered concurrently with cobicistat. Clinical monitoring for adverse effects, such as increased anticholinergic activity, is recommended during coadministration. Cobicistat is a CYP3A4 inhibitor, while oxybutynin is a CYP3A4 substrate.
Ergotamine; Caffeine: (Minor) Consuming greater than 400 mg/day caffeine has been associated with the development of urinary incontinence. Caffeine may aggravate bladder symptoms, increase urine output, and counteract the effectiveness of drugs used to treat overactive bladder such as oxybutynin. Patients may wish to limit their intake of caffeinated drugs, dietary supplements (e.g., guarana), or beverages (e.g., green tea, other teas, coffee, colas).
Erythromycin: (Moderate) Monitor for oxybutynin-related adverse reactions if coadministration with erythromycin is necessary. Oxybutynin is a CYP3A substrate and erythromycin is a moderate CYP3A inhibitor. Concomitant use with moderate CYP3A inhibitors may alter the mean pharmacokinetic parameters of oxybutynin, although the clinical relevance of these potential interactions is unknown.
Ethanol: (Major) Advise patients to avoid alcohol consumption while taking oxybutynin. Alcohol is a CNS-depressant and may cause additive sedative effects when used concomitantly with oxybutynin. (Moderate) Alcohol is a CNS-depressant and may cause additive sedative effects when used concomitantly with oxybutynin.
Fedratinib: (Minor) Monitor for oxybutynin-related adverse reactions if coadministration with fedratinib is necessary. Oxybutynin is a CYP3A4 substrate and fedratinib is a moderate CYP3A inhibitor. Concomitant use with moderate CYP3A4 inhibitors may alter the mean pharmacokinetic parameters of oxybutynin, although the clinical relevance of these potential interactions is unknown.
Fentanyl: (Moderate) Monitor for signs of urinary retention or reduced gastric motility during concomitant fentanyl and oxybutynin use. Concomitant use may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.
Fluconazole: (Moderate) Monitor for oxybutynin-related adverse reactions if coadministration with fluconazole is necessary. Oxybutynin is a CYP3A substrate and fluconazole is a moderate CYP3A inhibitor. Concomitant use with moderate CYP3A inhibitors may alter the mean pharmacokinetic parameters of oxybutynin, although the clinical relevance of these potential interactions is unknown.
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.
Fluvoxamine: (Moderate) Oxybutynin is metabolized by CYP3A4. Serum concentrations of oxybutynin may be increased if coadministered with inhibitors of CYP3A4 including fluvoxamine. The manufacturer recommends that caution when oxybutynin is co-administered with CYP3A4 inhibitors.
Fosamprenavir: (Moderate) Monitor for an increase in oxybutynin-related adverse reactions if coadministration with protease inhibitors is necessary. Oxybutynin is a CYP3A substrate and protease inhibitors are moderate to strong CYP3A inhibitors. Coadministration with another strong CYP3A inhibitor increased mean oxybutynin plasma concentrations by approximately 2-fold. Concomitant use with moderate CYP3A inhibitors may alter the mean pharmacokinetic parameters of oxybutynin, although the clinical relevance of these potential interactions is unknown.
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.
Glycopyrronium: (Moderate) Although glycopyrronium is minimally absorbed into the systemic circulation after topical application, there is the potential for glycopyrronium to have additive anticholinergic effects when administered with other antimuscarinics. Per the manufaturer, avoid concomitant administration of glycopyrronium with other anticholinergic medications.
Grapefruit juice: (Moderate) Oxybutynin is metabolized by CYP3A4. Inhibitors of the CYP3A4 enzyme system, such as grapefruit juice, may alter oxybutynin mean pharmacokinetic parameters. The clinical significance of such interactions is not known; however, the manufacturer recommends that caution be used when oxybutynin is co-administered with CYP3A4 inhibitors.
Green Tea: (Minor) Some green tea products contain caffeine. Consuming more than 400 mg/day caffeine has been associated with the development of urinary incontinence. Caffeine may aggravate bladder symptoms and counteract the effectiveness of drugs used to treat overactive bladder such as oxybutynin.
Guaifenesin; Hydrocodone: (Moderate) Monitor for signs of urinary retention or reduced gastric motility during concomitant hydrocodone and oxybutynin use. Concomitant use may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.
Homatropine; Hydrocodone: (Moderate) Monitor for signs of urinary retention or reduced gastric motility during concomitant hydrocodone and oxybutynin use. Concomitant use may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.
Hydrocodone: (Moderate) Monitor for signs of urinary retention or reduced gastric motility during concomitant hydrocodone and oxybutynin use. Concomitant use may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.
Hydrocodone; Ibuprofen: (Moderate) Monitor for signs of urinary retention or reduced gastric motility during concomitant hydrocodone and oxybutynin use. Concomitant use may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.
Hydrocodone; Pseudoephedrine: (Moderate) Monitor for signs of urinary retention or reduced gastric motility during concomitant hydrocodone and oxybutynin use. Concomitant use may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.
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.
Hydroquinone: (Moderate) The effect on the pharmacokinetics of oxybutynin topical gel when sunscreens were applied 30 minutes before or after oxybutynin gel was evaluated in a single-dose randomized crossover study (n=16). The study revealed no difference in the absorption of oxybutynin gel when applied in this manner. However, the effects of sunscreen on oxybutynin absorption when used within 30 minutes of gel application have not been studied. Therefore, the manufacturer recommends that patients use sunscreen either 30 minutes before or after gel application.
Ibritumomab Tiuxetan: (Moderate) Use anticholinergics, such as oxybutynin, and concomitant solid oral dosage forms of potassium chloride with caution due to risk for gastrointestinal mucosal injury. Anticholinergics may decrease gastric motility and increase the transit time of solid oral dosage forms of potassium chloride leading to prolonged contact with the gastrointestinal mucosa.
Ibuprofen; Oxycodone: (Moderate) Monitor for signs of urinary retention or reduced gastric motility during concomitant oxycodone and oxybutynin use. Concomitant use may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.
Idelalisib: (Major) Avoid concomitant use of idelalisib, a strong CYP3A inhibitor, with oxybutynin, a CYP3A substrate, as oxybutynin toxicities may be significantly increased. The AUC of a sensitive CYP3A substrate was increased 5.4-fold when coadministered with idelalisib.
Imatinib: (Moderate) Oxybutynin is metabolized by CYP3A4. Serum concentrations of oxybutynin may be increased if coadministered with inhibitors of CYP3A4 including imatinib. The manufacturer recommends that caution when oxybutynin is co-administered with CYP3A4 inhibitors.
Indinavir: (Moderate) Monitor for an increase in oxybutynin-related adverse reactions if coadministration with protease inhibitors is necessary. Oxybutynin is a CYP3A substrate and protease inhibitors are moderate to strong CYP3A inhibitors. Coadministration with another strong CYP3A inhibitor increased mean oxybutynin plasma concentrations by approximately 2-fold. Concomitant use with moderate CYP3A inhibitors may alter the mean pharmacokinetic parameters of oxybutynin, although the clinical relevance of these potential interactions is unknown.
Ipratropium: (Moderate) Although ipratropium is minimally absorbed into the systemic circulation after inhalation, there is the potential for additive anticholinergic effects when administered with other antimuscarinic or anticholinergic medications. Per the manufacturer, avoid coadministration.
Ipratropium; Albuterol: (Moderate) Although ipratropium is minimally absorbed into the systemic circulation after inhalation, there is the potential for additive anticholinergic effects when administered with other antimuscarinic or anticholinergic medications. Per the manufacturer, avoid coadministration.
Isavuconazonium: (Moderate) Concomitant use of isavuconazonium with oxybutynin may result in increased serum concentrations of oxybutynin. Oxybutynin is a substrate of the hepatic isoenzyme CYP3A4; isavuconazole, the active moiety of isavuconazonium, is a moderate inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are used together.
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. In addition, oxybutynin is metabolized by CYP3A4. Anticholinergic side effects may be increased when oxybutynin is used in combination with itraconazole. In healthy subjects receiving both itraconazole and oxybutynin, serum concentrations of oxybutynin were doubled; however, the serum concentrations of the active metabolite, N-desethoxybutynin, were not significantly changed. Since the pharmacologic effects of oxybutynin are mainly due to the active metabolite, adverse reactions associated with this interaction should be minimal.
Ketoconazole: (Moderate) Monitor for an increase in oxybutynin-related adverse reactions if coadministration with ketoconazole is necessary. Oxybutynin is a CYP3A4 substrate and ketoconazole is a strong CYP3A4 inhibitor. Coadministration with ketoconazole increased mean oxybutynin plasma concentrations by approximately 2-fold.
Lansoprazole; Amoxicillin; Clarithromycin: (Moderate) Oxybutynin is metabolized by CYP3A4. Serum concentrations of oxybutynin may be increased when administered with inhibitors of the CYP3A4 enzyme system, including clarithromycin.
Lefamulin: (Minor) Monitor for oxybutynin-related adverse reactions if coadministration with oral lefamulin is necessary. Oxybutynin is a CYP3A4 substrate and oral lefamulin is a moderate CYP3A inhibitor; an interaction is not expected with intravenous lefamulin. Concomitant use with moderate CYP3A4 inhibitors may alter the mean pharmacokinetic parameters of oxybutynin, although the clinical relevance of these potential interactions is unknown.
Lenacapavir: (Moderate) Monitor for an increase in oxybutynin-related adverse reactions if coadministration with lenacapavir is necessary. Oxybutynin is a CYP3A substrate and lenacapavir is a moderate CYP3A inhibitor. Concomitant use with moderate CYP3A inhibitors may alter the mean pharmacokinetic parameters of oxybutynin, although the clinical relevance of these potential interactions is unknown.
Lesinurad: (Moderate) Lesinurad may decrease the systemic exposure and therapeutic efficacy of oxybutynin; monitor for potential reduction in efficacy. Oxybutynin is a CYP3A substrate, and lesinurad is a weak CYP3A inducer.
Lesinurad; Allopurinol: (Moderate) Lesinurad may decrease the systemic exposure and therapeutic efficacy of oxybutynin; monitor for potential reduction in efficacy. Oxybutynin is a CYP3A substrate, and lesinurad is a weak CYP3A inducer.
Letermovir: (Moderate) A clinically relevant increase in the plasma concentration of oxybutynin may occur if given with letermovir. In patients who are also receiving treatment with cyclosporine, the magnitude of this interaction may be amplified. Oxybutynin is primarily metabolized by CYP3A4. Letermovir is a moderate CYP3A4 inhibitor; however, when given with cyclosporine, the combined effect on CYP3A4 substrates may be similar to a strong CYP3A4 inhibitor. In a drug interaction study, concurrent administration with another strong CYP3A4 inhibitor increased mean oxybutynin plasma concentrations by approximately 2-fold.
Levocetirizine: (Moderate) Monitor for signs or symptoms of anticholinergic toxicity during concomitant cetirizine and oxybutynin use. Concomitant use may result in additive anticholinergic adverse effects.
Levodopa: (Minor) Through central antimuscarinic actions, anticholinergics can potentiate the dopaminergic effects of levodopa. Antimuscarinics, by slowing GI transit, may also decrease levodopa bioavailability; however, this mechanism appears to be of modest clinical significance. Antimuscarinic agents targeted specifically for urinary incontinence may be less likely to produce pronounced effects on levodopa response than those with more pronounced systemic action.
Levoketoconazole: (Moderate) Monitor for an increase in oxybutynin-related adverse reactions if coadministration with ketoconazole is necessary. Oxybutynin is a CYP3A4 substrate and ketoconazole is a strong CYP3A4 inhibitor. Coadministration with ketoconazole increased mean oxybutynin plasma concentrations by approximately 2-fold.
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 or constipation-associated irritable bowel syndrome, such as linaclotide.
Lonafarnib: (Moderate) Monitor for an increase in oxybutynin-related adverse reactions if coadministration with lonafarnib is necessary. Oxybutynin is a CYP3A4 substrate and lonafarnib is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased mean oxybutynin plasma concentrations by approximately 2-fold.
Loop diuretics: (Minor) Diuretics can increase urinary frequency, which may aggravate bladder symptoms.
Lopinavir; Ritonavir: (Moderate) Monitor for an increase in oxybutynin-related adverse reactions if coadministration with protease inhibitors is necessary. Oxybutynin is a CYP3A substrate and protease inhibitors are moderate to strong CYP3A inhibitors. Coadministration with another strong CYP3A inhibitor increased mean oxybutynin plasma concentrations by approximately 2-fold. Concomitant use with moderate CYP3A inhibitors may alter the mean pharmacokinetic parameters of oxybutynin, although the clinical relevance of these potential interactions is unknown.
Loxapine: (Moderate) Loxapine has anticholinergic activity. The concomitant use of loxapine and other anticholinergic drugs can increase the risk of anticholinergic adverse reactions including exacerbation of glaucoma, constipation, and urinary retention. Depending on the agent used, additive drowsiness/dizziness may also occur.
Lubiprostone: (Moderate) Antimuscarinic drugs can promote constipation and pharmacodynamically oppose the action of drugs used for the treatment of constipation, such as lubiprostone. The clinical significance of these potential interactions is uncertain.
Luliconazole: (Moderate) Theoretically, luliconazole may increase the side effects of oxybutynin, which is a CYP (2C19 or 3A4) substrate. Monitor patients for adverse effects of oxybutynin, such as CNS and anticholinergic effects. In vitro, therapeutic doses of luliconazole inhibit the activity of CYP (2C19 or 3A4) and small systemic concentrations may be noted with topical application, particularly when applied to patients with moderate to severe tinea cruris. No in vivo drug interaction trials were conducted prior to the approval of luliconazole.
Lumacaftor; Ivacaftor: (Minor) Lumacaftor; ivacaftor may reduce the efficacy of oxybutynin by decreasing its systemic exposure; if used together, monitor patients for anticholinergic efficacy. Oxybutynin is a substrate of CYP3A4, and lumacaftor is a strong CYP3A inducer.
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 contribut

e to heat-related disorders. Monitor patients for heat intolerance, decreased sweating, or increased body temperature if lurasidone is used with antimuscarinics.
Macimorelin: (Major) Avoid use of macimorelin with drugs that may blunt the growth hormone response to macimorelin, such as antimuscarinic anticholinergic agents. Healthcare providers are advised to discontinue anticholinergics at least 1 week before administering macimorelin. Use of these medications together may impact the accuracy of the macimorelin growth hormone test.
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 oxybutynin is used concomitantly with other commonly used drugs with moderate to significant anticholinergic effects including maprotiline. Clinicians should note that anticholinergic effects might be seen not only on bladder smooth muscle, but also on GI function, the eye, and temperature regulation. Additive drowsiness may also occur.
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.
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.
Methohexital: (Moderate) Additive CNS depression may occur when oxybutynin is used concomitantly with other CNS-depressant drugs, including anxiolytics, sedatives, and hypnotics. In addition, because oxybutynin is metabolized by CYP3A4, administration with drugs that induce CYP3A4 (such as barbiturates) may reduce the serum concentration and effects of oxybutynin. Patients receiving these drugs concomitantly should be monitored for reduced efficacy.
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.
Mifepristone: (Moderate) Monitor for an increase in oxybutynin-related adverse reactions if coadministration with mifepristone is necessary. Oxybutynin is a CYP3A substrate and mifepristone is a strong CYP3A inhibitor. Coadministration with another strong CYP3A inhibitor increased mean oxybutynin plasma concentrations by approximately 2-fold.
Mirabegron: (Moderate) Mirabegron should be administered with caution in patients taking antimuscarinic medications for the treatment of overactive bladder, such as oxybutynin, because of the risk of urinary retention. Monitor for symptoms of urinary difficulties or urinary retention. Patients may note constipation or dry mouth with use of these drugs together.
Mitotane: (Moderate) Mitotane is a strong CYP3A4 inducer and oxybutynin is a CYP3A4 substrate. Coadministration may result in decreased plasma concentrations of oxybutynin. If these drugs are used together, monitor patients for decreased oxybutynin efficacy; oxybutynin dosage adjustments may be needed.
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 for signs of urinary retention or reduced gastric motility during concomitant morphine and oxybutynin use. Concomitant use may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.
Morphine; Naltrexone: (Moderate) Monitor for signs of urinary retention or reduced gastric motility during concomitant morphine and oxybutynin use. Concomitant use may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.
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.
Nefazodone: (Moderate) Oxybutynin is metabolized by CYP3A4. Inhibitors of the CYP3A4 enzyme, such as nefazodone, may increase the serum concentrations of oxybutynin. The manufacturer recommends caution when oxybutynin is co-administered with CYP3A4 inhibitors.
Nelfinavir: (Moderate) Monitor for an increase in oxybutynin-related adverse reactions if coadministration with protease inhibitors is necessary. Oxybutynin is a CYP3A substrate and protease inhibitors are moderate to strong CYP3A inhibitors. Coadministration with another strong CYP3A inhibitor increased mean oxybutynin plasma concentrations by approximately 2-fold. Concomitant use with moderate CYP3A inhibitors may alter the mean pharmacokinetic parameters of oxybutynin, although the clinical relevance of these potential interactions is unknown.
Neostigmine: (Moderate) Oxybutynin is an antimuscarinic; the muscarinic actions of neostigmine could be antagonized when used concomitantly with oxybutynin.
Neostigmine; Glycopyrrolate: (Moderate) Oxybutynin is an antimuscarinic; the muscarinic actions of neostigmine could be antagonized when used concomitantly with oxybutynin.
Nirmatrelvir; Ritonavir: (Moderate) Monitor for an increase in oxybutynin-related adverse reactions if coadministration with protease inhibitors is necessary. Oxybutynin is a CYP3A substrate and protease inhibitors are moderate to strong CYP3A inhibitors. Coadministration with another strong CYP3A inhibitor increased mean oxybutynin plasma concentrations by approximately 2-fold. Concomitant use with moderate CYP3A inhibitors may alter the mean pharmacokinetic parameters of oxybutynin, although the clinical relevance of these potential interactions is unknown.
Olanzapine: (Moderate) Additive anticholinergic effects may be seen when olanzapine and anticholinergics are used concomitantly; use with caution. Use of olanzapine and other drugs with anticholinergic activity can increase the risk for severe gastrointestinal adverse reactions related to hypomotility. Olanzapine exhibits anticholinergic activity. Adverse 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 anticholinergic agent used.
Olanzapine; Fluoxetine: (Moderate) Additive anticholinergic effects may be seen when olanzapine and anticholinergics are used concomitantly; use with caution. Use of olanzapine and other drugs with anticholinergic activity can increase the risk for severe gastrointestinal adverse reactions related to hypomotility. Olanzapine exhibits anticholinergic activity. Adverse 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 anticholinergic agent used.
Olanzapine; Samidorphan: (Moderate) Additive anticholinergic effects may be seen when olanzapine and anticholinergics are used concomitantly; use with caution. Use of olanzapine and other drugs with anticholinergic activity can increase the risk for severe gastrointestinal adverse reactions related to hypomotility. Olanzapine exhibits anticholinergic activity. Adverse 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 anticholinergic agent used.
Oliceridine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when oliceridine is used with oxybutynin. Use of anticholinergics may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.
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.
Oritavancin: (Minor) Oxybutynin is metabolized by CYP3A4; oritavancin is a weak CYP3A4 inducer. Plasma concentrations and efficacy of oxybutynin may be reduced if these drugs are administered concurrently.
Orphenadrine: (Moderate) Additive anticholinergic effects may be seen when oxybutynin is used concomitantly with other drugs that have moderate to significant anticholinergic effects, including orphenadrine. Clinicians should note that anticholinergic effects might be seen not only on bladder smooth muscle, but also on GI function, the eye, and temperature regulation. Additive drowsiness may also occur.
Oxycodone: (Moderate) Monitor for signs of urinary retention or reduced gastric motility during concomitant oxycodone and oxybutynin use. Concomitant use may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.
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.
Paroxetine: (Moderate) Monitor for signs or symptoms of anticholinergic toxicity during concomitant anticholinergic medication and paroxetine use. Concomitant use may result in additive anticholinergic adverse effects.
Pazopanib: (Moderate) Pazopanib is a weak inhibitor of CYP3A4. Coadministration of pazopanib and oxybutynin a CYP3A4 substrate, may cause an increase in systemic concentrations of oxybutynin. Use caution when administering these drugs concomitantly.
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 medications 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 medications 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.
Pentobarbital: (Moderate) Additive CNS depression may occur when oxybutynin is used concomitantly with other CNS-depressant drugs, including anxiolytics, sedatives, and hypnotics. In addition, because oxybutynin is metabolized by CYP3A4, administration with drugs that induce CYP3A4 (such as barbiturates) may reduce the serum concentration and effects of oxybutynin. Patients receiving these drugs concomitantly should be monitored for reduced efficacy.
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.
Phenobarbital: (Moderate) Additive CNS depression may occur when oxybutynin is used concomitantly with other CNS-depressant drugs, including anxiolytics, sedatives, and hypnotics. In addition, because oxybutynin is metabolized by CYP3A4, administration with drugs that induce CYP3A4 (such as barbiturates) may reduce the serum concentration and effects of oxybutynin. Patients receiving these drugs concomitantly should be monitored for reduced efficacy.
Phenobarbital; Hyoscyamine; Atropine; Scopolamine: (Moderate) Additive CNS depression may occur when oxybutynin is used concomitantly with other CNS-depressant drugs, including anxiolytics, sedatives, and hypnotics. In addition, because oxybutynin is metabolized by CYP3A4, administration with drugs that induce CYP3A4 (such as barbiturates) may reduce the serum concentration and effects of oxybutynin. Patients receiving these drugs concomitantly should be monitored for reduced efficacy.
Phentermine; Topiramate: (Moderate) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Physostigmine: (Moderate) Oxybutynin is an antimuscarinic; the muscarinic actions of physostigmine could be antagonized when used concomitantly with oxybutynin.
Posaconazole: (Moderate) Posaconazole and oxybutynin should be coadministered with caution due to an increased potential for oxybutynin-related adverse events. Posaconazole is a potent inhibitor of CYP3A4, an isoenzyme responsible for the metabolism of oxybutynin. These drugs used in combination may result in elevated oxybutynin plasma concentrations, causing an increased risk for oxybutynin-related adverse events.
Potassium Bicarbonate: (Moderate) Use anticholinergics, such as oxybutynin, and concomitant solid oral dosage forms of potassium chloride with caution due to risk for gastrointestinal mucosal injury. Anticholinergics may decrease gastric motility and increase the transit time of solid oral dosage forms of potassium chloride leading to prolonged contact with the gastrointestinal mucosa.
Potassium Chloride: (Moderate) Use anticholinergics, such as oxybutynin, and concomitant solid oral dosage forms of potassium chloride with caution due to risk for gastrointestinal mucosal injury. Anticholinergics may decrease gastric motility and increase the transit time of solid oral dosage forms of potassium chloride leading to prolonged contact with the gastrointestinal mucosa.
Potassium-sparing diuretics: (Minor) Diuretics can increase urinary frequency, which may aggravate bladder symptoms.
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.
Primidone: (Moderate) Additive CNS depression may occur when oxybutynin is used concomitantly with other CNS-depressant drugs, including anxiolytics, sedatives, and hypnotics. In addition, because oxybutynin is metabolized by CYP3A4, administration with drugs that induce CYP3A4 (such as barbiturates) may reduce the serum concentration and effects of oxybutynin. Patients receiving these drugs concomitantly should be monitored for reduced efficacy.
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) Monitor for signs or symptoms of anticholinergic toxicity during concomitant promethazine and oxybutynin use. Concomitant use may result in additive anticholinergic adverse effects.
Promethazine; Dextromethorphan: (Moderate) Monitor for signs or symptoms of anticholinergic toxicity during concomitant promethazine and oxybutynin use. Concomitant use may result in additive anticholinergic adverse effects.
Promethazine; Phenylephrine: (Moderate) Monitor for signs or symptoms of anticholinergic toxicity during concomitant promethazine and oxybutynin use. Concomitant use may result in additive anticholinergic adverse effects.
Protease inhibitors: (Moderate) Monitor for an increase in oxybutynin-related adverse reactions if coadministration with protease inhibitors is necessary. Oxybutynin is a CYP3A substrate and protease inhibitors are moderate to strong CYP3A inhibitors. Coadministration with another strong CYP3A inhibitor increased mean oxybutynin plasma concentrations by approximately 2-fold. Concomitant use with moderate CYP3A inhibitors may alter the mean pharmacokinetic parameters of oxybutynin, although the clinical relevance of these potential interactions is unknown.
Pyridostigmine: (Moderate) Oxybutynin is an antimuscarinic; the muscarinic actions of pyridostigmine could be antagonized when used concomitantly with oxybutynin.
Quetiapine: (Moderate) Monitor for signs or symptoms of anticholinergic toxicity during concomitant quetiapine and oxybutynin use. Concomitant use may result in additive anticholinergic adverse effects.
Quinidine: (Moderate) The anticholinergic effects of quinidine may be significant and may be enhanced when combined with antimuscarinics.
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.
Revefenacin: (Moderate) Although revefenacin is minimally absorbed into the systemic circulation after inhalation, there is the potential for additive anticholinergic effects when administered with other antimuscarinics. Avoid concomitant administration with other anticholinergic and antimucarinic medications.
Ribociclib: (Moderate) Monitor for an increase in oxybutynin-related adverse reactions if coadministration with ribociclib is necessary. Oxybutynin is a CYP3A4 substrate and ribociclib is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased mean oxybutynin plasma concentrations by approximately 2-fold.
Ribociclib; Letrozole: (Moderate) Monitor for an increase in oxybutynin-related adverse reactions if coadministration with ribociclib is necessary. Oxybutynin is a CYP3A4 substrate and ribociclib is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased mean oxybutynin plasma concentrations by approximately 2-fold.
Ritlecitinib: (Moderate) Monitor for an increase in oxybutynin-related adverse reactions if coadministration with ritlecitinib is necessary. Oxybutynin is a CYP3A substrate and ritlecitinib is a moderate CYP3A inhibitor. Concomitant use with moderate CYP3A inhibitors may alter the mean pharmacokinetic parameters of oxybutynin, although the clinical relevance of these potential interactions is unknown.
Ritonavir: (Moderate) Monitor for an increase in oxybutynin-related adverse reactions if coadministration with protease inhibitors is necessary. Oxybutynin is a CYP3A substrate and protease inhibitors are moderate to strong CYP3A inhibitors. Coadministration with another strong CYP3A inhibitor increased mean oxybutynin plasma concentrations by approximately 2-fold. Concomitant use with moderate CYP3A inhibitors may alter the mean pharmacokinetic parameters of oxybutynin, although the clinical relevance of these potential interactions is unknown.
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.
Saquinavir: (Moderate) Monitor for an increase in oxybutynin-related adverse reactions if coadministration with protease inhibitors is necessary. Oxybutynin is a CYP3A substrate and protease inhibitors are moderate to strong CYP3A inhibitors. Coadministration with another strong CYP3A inhibitor increased mean oxybutynin plasma concentrations by approximately 2-fold. Concomitant use with moderate CYP3A inhibitors may alter the mean pharmacokinetic parameters of oxybutynin, although the clinical relevance of these potential interactions is unknown.
Secobarbital: (Moderate) Additive CNS depression may occur when oxybutynin is used concomitantly with other CNS-depressant drugs, including anxiolytics, sedatives, and hypnotics. In addition, because oxybutynin is metabolized by CYP3A4, administration with drugs that induce CYP3A4 (such as barbiturates) may reduce the serum concentration and effects of oxybutynin. Patients receiving these drugs concomitantly should be monitored for reduced efficacy.
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) Monitor for signs or symptoms of anticholinergic toxicity during concomitant sedating H1-blocker and oxybutynin use. Concomitant use may result in additive anticholinergic adverse effects.
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.
Sodium Sulfate; Magnesium Sulfate; Potassium Chloride: (Moderate) Use anticholinergics, such as oxybutynin, and concomitant solid oral dosage forms of potassium chloride with caution due to risk for gastrointestinal mucosal injury. Anticholinergics may decrease gastric motility and increase the transit time of solid oral dosage forms of potassium chloride leading to prolonged contact with the gastrointestinal mucosa.
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.
Sunscreens: (Moderate) The effect on the pharmacokinetics of oxybutynin topical gel when sunscreens were applied 30 minutes before or after oxybutynin gel was evaluated in a single-dose randomized crossover study (n=16). The study revealed no difference in the absorption of oxybutynin gel when applied in this manner. However, the effects of sunscreen on oxybutynin absorption when used within 30 minutes of gel application have not been studied. Therefore, the manufacturer recommends that patients use sunscreen either 30 minutes before or after gel application.
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.
Tenapanor: (Moderate) Anticholinergics can promote constipation and pharmacodynamically oppose the action of drugs used for the treatment of constipation or constipation-associated irritable bowel syndrome, such as tenapanor.
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.
Thioridazine: (Moderate) Additive anticholinergic effects may be seen when drugs with anticholinergic properties like thioridazine are used concomitantly with anticholinergic agents. Adverse 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.
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: (Major) Avoid concomitant use of anticholinergic medications and tiotropium due to increased risk for anticholinergic adverse effects.
Tiotropium; Olodaterol: (Major) Avoid concomitant use of anticholinergic medications and tiotropium due to increased risk for anticholinergic adverse effects.
Tipranavir: (Moderate) Monitor for an increase in oxybutynin-related adverse reactions if coadministration with protease inhibitors is necessary. Oxybutynin is a CYP3A substrate and protease inhibitors are moderate to strong CYP3A inhibitors. Coadministration with another strong CYP3A inhibitor increased mean oxybutynin plasma concentrations by approximately 2-fold. Concomitant use with moderate CYP3A inhibitors may alter the mean pharmacokinetic parameters of oxybutynin, although the clinical relevance of these potential interactions is unknown.
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) Monitor for decreased sweating and increased body temperature, especially in hot weather, during concomitant use of topiramate and other drugs that predispose persons to heat-related disorders, such as anticholinergic medications. Concomitant use increases the risk for oligohidrosis and hyperthermia.
Tramadol: (Moderate) Monitor for signs of urinary retention or reduced gastric motility during concomitant tramadol and oxybutynin use. Concomitant use may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.
Tramadol; Acetaminophen: (Moderate) Monitor for signs of urinary retention or reduced gastric motility during concomitant tramadol and oxybutynin use. Concomitant use may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus.
Trandolapril; Verapamil: (Moderate) Monitor for oxybutynin-related adverse reactions if coadministration with verapamil is necessary. Oxybutynin is a CYP3A4 substrate and verapamil is a moderate CYP3A inhibitor. Concomitant use with moderate CYP3A4 inhibitors may alter the mean pharmacokinetic parameters of oxybutynin, although the clinical relevance of these potential interactions is unknown.
Tricyclic antidepressants: (Moderate) Monitor for signs or symptoms of anticholinergic toxicity during concomitant tricyclic antidepressant and oxybutynin use. Concomitant use may result in additive anticholinergic adverse effects.
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.
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.
Tucatinib: (Moderate) Monitor for an increase in oxybutynin-related adverse reactions if coadministration with tucatinib is necessary. Oxybutynin is a CYP3A4 substrate and tucatinib is a strong CYP3A4 inhibitor. Coadministration with another strong CYP3A4 inhibitor increased mean oxybutynin plasma concentrations by approximately 2-fold.
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.
Vemurafenib: (Moderate) Vemuraifenib is an inducer of CYP3A4 and decreased plasma concentrations of drugs metabolized by this enzyme, such as oxybutynin, could be expected with concurrent use. Use caution, and monitor therapeutic effects of oxybutynin when coadministered with vemurafenib.
Verapamil: (Moderate) Monitor for oxybutynin-related adverse reactions if coadministration with verapamil is necessary. Oxybutynin is a CYP3A4 substrate and verapamil is a moderate CYP3A inhibitor. Concomitant use with moderate CYP3A4 inhibitors may alter the mean pharmacokinetic parameters of oxybutynin, although the clinical relevance of these potential interactions is unknown.
Vibegron: (Moderate) Vibegron should be administered with caution in patients taking anticholinergics because of potential for an increased risk of urinary retention. Monitor for symptoms of urinary difficulties or urinary retention. Patients may note constipation or dry mouth with use of these drugs together.
Vonoprazan; Amoxicillin; Clarithromycin: (Moderate) Oxybutynin is metabolized by CYP3A4. Serum concentrations of oxybutynin may be increased when administered with inhibitors of the CYP3A4 enzyme system, including clarithromycin.
Voriconazole: (Moderate) Oxybutynin is metabolized by CYP3A4. Inhibitors of the CYP3A4 enzyme, such as voriconazole, may increase the serum concentrations of oxybutynin. The manufacturer recommends caution when oxybutynin is co-administered with CYP3A4 inhibitors.
Voxelotor: (Minor) Monitor for oxybutynin-related adverse reactions if coadministration with voxelotor is necessary. Oxybutynin is a CYP3A substrate and voxelotor is a moderate CYP3A inhibitor. Concomitant use with moderate CYP3A inhibitors may alter the mean pharmacokinetic parameters of oxybutynin, although the clinical relevance of these potential interactions is unknown.
Zafirlukast: (Moderate) Oxybutynin is metabolized by CYP3A4. Inhibitors of the CYP3A4 enzyme, such as zafirlukast, may increase the serum concentrations of oxybutynin. The manufacturer recommends caution when oxybutynin is co-administered with CYP3A4 inhibitors.
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.

How Supplied

Ditropan XL/Oxybutynin/Oxybutynin Chloride Oral Tab ER: 5mg, 10mg, 15mg
Ditropan/Oxybutynin/Oxybutynin Chloride Oral Sol: 5mg, 5mL
Ditropan/Oxybutynin/Oxybutynin Chloride Oral Tab: 2.5mg, 5mg
Gelnique Transdermal Gel: 10%
Oxybutynin/Oxytrol/Oxytrol for Women Transdermal Film ER: 3.9mg, 24h

Maximum Dosage
Adults

20 mg/day PO for immediate-release dosage forms; 30 mg/day PO for extended-release Ditropan XL.

Geriatric

20 mg/day PO for immediate-release dosage forms; 30 mg/day PO for extended-release Ditropan XL.

Adolescents

15—20 mg/day PO for immediate-release dosage forms; 20 mg/day PO for extended-release Ditropan XL.

Children

>= 6 years: 15 mg/day PO for immediate-release dosage forms; 20 mg/day PO for extended-release Ditropan XL.
5 years: 15 mg/day PO for immediate-release dosage forms.
1—4 years: Safety and efficacy have not been established.

Mechanism Of Action

Oxybutynin is a tertiary amine ester that exerts antimuscarinic (atropine-like) and antispasmodic (papaverine-like) actions on smooth muscle. Antimuscarinic activity resides predominately in the R-isomer and a metabolite, desethyloxybutynin, has pharmacological activity similar to that of oxybutynin. Oxybutynin exerts a direct antispasmodic effect on smooth muscle and inhibits the muscarinic action of acetylcholine on smooth muscle. The effects on the bladder detrusor muscle are mediated via M3 receptors. Oxybutynin exhibits only one-fifth of the anticholinergic activity of atropine on the rabbit detrusor muscle, but 4 to 10 times the antispasmodic activity. No blocking effects occur at skeletal neuromuscular junctions or autonomic ganglia (antinicotinic effects). Clinically, oxybutynin relaxes bladder smooth muscle. In patients with conditions characterized by involuntary bladder contractions, cystometric studies have demonstrated that oxybutynin increases bladder (vesical) capacity, diminishes the frequency of uninhibited contractions of the detrusor muscle, and delays the initial desire to void. Oxybutynin thus decreases urgency and the frequency of both incontinent episodes and voluntary urination.

Pharmacokinetics

Oxybutynin is administered topically as a transdermal patch or gel and orally.
 
Once in the systemic circulation, oxybutynin is widely distributed to body tissues. Distribution of oxybutynin is not well characterized, however, oxybutynin has an affinity for anticholinergic receptors in the urinary tract, salivary glands, and CNS. Oxybutynin exhibits dose-dependent, linear pharmacokinetics.
 
The metabolite desethyloxybutynin is active and is equipotent to oxybutynin with respect to its antimuscarinic actions. A second metabolite, phenylcyclohexylglycolic acid, is inactive. The elimination half-life (half-life) of oxybutynin is 2—5 hours. Less than 0.1% of oxybutynin or desethyloxybutynin appears in the urine unchanged.

Oral Route

Following oral administration of immediate-release oxybutynin dosage forms, absorption from the gut is rapid, with peak concentrations occurring at 1 hour. Antispasmodic activity occurs within 30—60 minutes of administration and can last for 6—10 hours. Administration of an oral controlled-release formulation (i.e., Ditropan XL), results in a Cmax at 4—6 hours and consistent 24-hour plasma-concentrations at steady-state. Coadministration of oxybutynin solution with food results in a slight delay in absorption and a 25% increase in bioavailability. Oxybutynin is widely distributed in body tissues following systemic absorption. Oxybutynin enantiomers are highly bound (>99%) to plasma proteins. Both enantiomers of desethyloxybutynin are also highly bound (>97%). The major binding protein is alpha-1 acid glycoprotein. After oral administration, oxybutynin is extensively metabolized via the enteric and hepatic CYP450 3A4 isoenzymes.

Topical Route

Topical Gels: Absorption of oxybutynin topical gel is similar after application to the abdomen, upper arm/shoulders or thighs. Steady-state concentrations are achieved within 3 to 7 days of continuous daily dosing.
 
Transdermal System: The transdermal patch (Oxytrol) delivers 3.9 mg/day of oxybutynin through the skin by passive diffusion. Absorption of oxybutynin is bioequivalent after application of the patch to the abdomen, buttocks, or hips. Plasma concentrations increase for approximately 24—48 hours after patch application; steady-state concentrations are maintained for up to 96 hours. Transdermal administration of oxybutynin bypasses enteric and hepatic first-pass metabolism. Since the skin contains only small amounts of CYP3A4, limited pre-systemic metabolism occurs with transdermal administration.

Pregnancy And Lactation
Pregnancy

Oxybutynin should not be given during pregnancy unless, in the judgment of the physician, the probable clinical benefits outweigh the possible risks. There are no adequate and well-controlled studies of topical or oral oxybutynin use in human pregnancy to evaluate for a drug-associated risk of major birth defects, miscarriages, or adverse maternal or fetal outcomes. Subcutaneous administration to rats at doses up to 25 mg/kg (approximately 50-times the human exposure based on surface area) and to rabbits at doses up to 0.4 mg/kg (approximately 1-times the human exposure) revealed no evidence of harm to the fetus due to oxybutynin.

There are no data on the presence of oxybutynin in human milk, the effects on a breastfed infant, or the effects on milk production. Because many drugs are excreted in human milk, caution should be exercised when oxybutynin is administered to a nursing woman. Because an infant is usually very sensitive to anticholinergic effects of drugs, there may be a risk for adverse effects if the infant is exposed to oxybutynin via breast-feeding. Lactation suppression has been reported during postmarketing use of immediate-release oxybutynin. Consider the benefits of breast-feeding, the risk of potential infant drug exposure, and the risk of an untreated or inadequately treated condition.