OXYBUTYNIN Drug Interactions: What You Need to Know

INTERACTIONS The concomitant use of oxybutynin with other anticholinergic drugs or with other agents which produce dry mouth, constipation, somnolence (drowsiness), and/or other anticholinergic-like effects may increase the frequency and/or severity of such effects. Anticholinergic agents may potentially alter the absorption of some concomitantly administered drugs due to anticholinergic effects on gastrointestinal motility. This may be of concern for drugs with a narrow therapeutic index. Anticholinergic agents may also antagonize the effects of prokinetic agents, such as metoclopramide. Mean oxybutynin chloride plasma concentrations were approximately 2 fold higher when oxybutynin chloride extended-release tablet was administered with ketoconazole, a potent CYP3A4 inhibitor. Other inhibitors of the cytochrome P450 3A4 enzyme system, such as antimycotic agents (e.g., itraconazole and miconazole) or macrolide antibiotics (e.g., erythromycin and clarithromycin), may alter oxybutynin mean pharmacokinetic parameters (i.e., C max and AUC). The clinical relevance of such potential interactions is not known. Caution should be used when such drugs are co-administered.

• Co-administration with other anticholinergic drugs may increase the frequency and/or severity of anticholinergic-like effects. ( Error! Hyperlink reference not valid. )
• Co-administration with strong cytochrome P450 (CYP) 3A4 inhibitors (e.g., ketoconazole) increases the systemic exposure of oxybutynin. ( Error! Hyperlink reference not valid. )

Oxybutynin chloride extended-release tablets are contraindicated in patients with urinary retention, gastric retention and other severe decreased gastrointestinal motility conditions, uncontrolled narrow-angle glaucoma. Oxybutynin chloride extended-release tablets are also contraindicated in patients who have demonstrated hypersensitivity to the drug substance or other components of the product. There have been reports of hypersensitivity reactions, including anaphylaxis and angiodema.

• Urinary retention ( Error! Hyperlink reference not valid. )
• Gastric Retention ( Error! Hyperlink reference not valid. )
• Uncontrolled narrow angle glaucoma ( Error! Hyperlink reference not valid. )
• Known hypersensitivity to oxybutynin chloride extended-release tablets, oxybutynin or any component of oxybutynin chloride extended-release tablets ( Error! Hyperlink reference not valid. )

AND PRECAUTIONS

• Angioedema: Angioedema has been reported with oxybutynin. If symptoms of angioedema occur, discontinue oxybutynin chloride extended-release tablets immediately and initiate appropriate therapy. ( 5.1 )
• Central Nervous System (CNS) effects: CNS effects have been reported with oxybutynin. If patient experiences anticholinergic CNS effects, consider dose adjustment or discontinuation of oxybutynin chloride extended-release tablets. ( 5.2 )
• Use with caution due to aggravation of symptoms:
• Pre-existing dementia in patients treated with cholinesterase inhibitors ( 5.2 ),
• Parkinson’s disease ( 5.2 ),
• Myasthenia gravis ( 5.3 ), and
• Decreased gastrointestinal motility in patients with autonomic neuropathy. ( 5.4 ).
• Urinary Retention: Use with caution in patients with clinically significant bladder outflow obstruction because of the risk of urinary retention ( 5.5 )
• Gastrointestinal Adverse Reactions: Use with caution in patients with gastrointestinal obstructive disorders or decreased intestinal motility due to risk of gastric retention. Use with caution in patients with gastroesophageal reflux or in patients concurrently taking drugs that can exacerbate esophagitis. ( 5.6 )

5.1 Angioedema Angioedema of the face, lips, tongue and/or larynx has been reported with oxybutynin. In some cases, angioedema occurred after the first dose. Angioedema associated with upper airway swelling may be life-threatening. If involvement of the tongue, hypopharynx, or larynx occurs, oxybutynin should be promptly discontinued and appropriate therapy and/or measures necessary to ensure a patent airway should be promptly provided.

5.2 Central Nervous System Effects Oxybutynin is associated with anticholinergic central nervous system (CNS) effects <span class="opacity-50 text-xs">[see Error! Hyperlink reference not valid. ]</span> . A variety of CNS anticholinergic effects have been reported, including hallucinations, agitation, confusion and somnolence. Patients should be monitored for signs of anticholinergic CNS effects, particularly in the first few months after beginning treatment or increasing the dose. Advise patients not to drive or operate heavy machinery until they know how oxybutynin chloride extended-release tablet affects them. If a patient experiences anticholinergic CNS effects, dose reduction or drug discontinuation should be considered. Oxybutynin chloride extended-release tablets should be used with caution in patients with preexisting dementia treated with cholinesterase inhibitors due to the risk of aggravation of symptoms. Oxybutynin chloride extended-release tablets should be used with caution in patients with Parkinson’s disease due to the risk of aggravation of symptoms.

5.3 Worsening of Symptoms of Myasthenia Gravis Oxybutynin chloride extended-release tablets should be used with caution in patients with myasthenia gravis due to the risk of aggravation of symptoms.

5.4 Worsening of Symptoms of Decreased Gastrointestinal Motility in Patients with Autonomic Neuropathy Oxybutynin chloride extended-release tablets should be used with caution in patients with autonomic neuropathy due to the risk of aggravation of symptoms of decreased gastrointestinal motility.

5.5 Urinary Retention Oxybutynin chloride extended-release tablets should be administered with caution to patients with clinically significant bladder outflow obstruction because of the risk of urinary retention <span class="opacity-50 text-xs">[see Error! Hyperlink reference not valid. ]</span> .

5.6 Gastrointestinal Adverse Reactions Oxybutynin chloride extended-release tablets should be administered with caution to patients with gastrointestinal obstructive disorders because of the risk of gastric retention <span class="opacity-50 text-xs">[see Error! Hyperlink reference not valid. ]</span> . Oxybutynin chloride extended-release tablets, like other anticholinergic drugs, may decrease gastrointestinal motility and should be used with caution in patients with conditions such as ulcerative colitis and intestinal atony. Oxybutynin chloride extended-release tablets should be used with caution in patients who have gastroesophageal reflux and/or who are concurrently taking drugs (such as bisphosphonates) that can cause or exacerbate esophagitis. As with any other nondeformable material, caution should be used when administering oxybutynin chloride extended-release tablets to patients with preexisting severe gastrointestinal narrowing (pathologic or iatrogenic). There have been rare reports of obstructive symptoms in patients with known strictures in association with the ingestion of other drugs in nondeformable controlled-release formulations.