Overview
Oxybutynin is an anticholinergic medication used to treat overactive bladder symptoms including urge urinary incontinence, urgency, and frequency. It works by relaxing bladder muscles to reduce involuntary contractions and increase bladder capacity. It is also indicated for pediatric patients with neurogenic detrusor overactivity.
Mechanism of Action
Oxybutynin acts as a competitive muscarinic acetylcholine receptor antagonist, blocking acetylcholine binding at postganglionic muscarinic receptors. This inhibits involuntary detrusor muscle contractions in the bladder, increases bladder capacity, and reduces urinary urgency and frequency.
Indications
- Treatment of overactive bladder with symptoms of urge urinary incontinence, urgency, and frequency
- Treatment of pediatric patients aged 6 years and older with symptoms of detrusor overactivity associated with neurological conditions (e.g., spina bifida)
Common Doses
- 5 mg extended-release tablet
- 10 mg extended-release tablet
- 15 mg extended-release tablet
- 5 mg immediate-release tablet
- 2.5 mg immediate-release tablet
Dosage
Extended-release tablets must be swallowed whole with liquids and not chewed, divided, or crushed. May be administered with or without food. Typical adult starting dose is 5-10 mg once daily, with maximum recommended dose of 30 mg daily.
Contraindications
- Urinary retention
- Gastric retention and other severe decreased gastrointestinal motility conditions
- Uncontrolled narrow-angle glaucoma
- Hypersensitivity to oxybutynin or any product components
Side Effects
- Dry mouth
- Constipation
- Somnolence (drowsiness)
- Blurred vision
- Dizziness
- Nausea
- Urinary retention
- Headache
- Abdominal pain
- Diarrhea
- Fatigue
Interactions
- Other anticholinergic drugs increase frequency/severity of anticholinergic effects
- Potent CYP3A4 inhibitors (ketoconazole, itraconazole, clarithromycin) increase oxybutynin plasma concentrations
- May alter absorption of drugs with narrow therapeutic index due to effects on GI motility
- May antagonize effects of prokinetic agents like metoclopramide
Counseling Points
- Swallow extended-release tablets whole - do not chew, crush, or divide
- May cause dry mouth - maintain good oral hygiene and consider sugar-free gum/candy
- May cause drowsiness or blurred vision - avoid driving until effects known
- Drink adequate fluids unless otherwise directed
- Report severe constipation, urinary retention, or vision changes
- Avoid excessive heat exposure due to decreased sweating