Antimuscarinic (anticholinergic) bladder relaxant
Pregnancy: Use with caution; limited data. Only if essential.
Oxybutynin
Brand names: Ditropan, Kentera (patch), Lyrinel XL
Adult dose
Dose: Immediate-release: 5 mg 2–3 times daily; Modified-release: 5–10 mg once daily
Route: Oral or transdermal patch
Frequency: 2–3 times daily (IR); once daily (MR); twice weekly (patch)
Max: 15–20 mg/day oral; 36 mg/2 days (patch)
OAB/detrusor overactivity: 5 mg BD-TDS (IR) or 5–10 mg OD (MR). Kentera patch (3.9 mg/24h): apply to abdomen/buttock twice weekly. MR formulation preferred (fewer CNS side effects). Elderly: start 2.5 mg BD.
Paediatric dose
Dose: 0.2 mg/kg
Route: Oral
Frequency: Two to three times daily
Max: 5 mg/dose (≥5 years)
Concentration: 2.5 mg/ml
≥5 years (neurogenic bladder/OAB): 2.5–5 mg two to three times daily. Do not use in children <5 years. Neurogenic bladder in children: paediatric urology/neurology specialist.
Dose adjustments
Renal
Use with caution in severe renal impairment.
Hepatic
Use with caution in severe hepatic impairment.
Paediatric weight-based calculator
≥5 years (neurogenic bladder/OAB): 2.5–5 mg two to three times daily. Do not use in children <5 years. Neurogenic bladder in children: paediatric urology/neurology specialist.
Clinical pearls
- Anticholinergic burden in elderly is cumulative — consider switching to beta-3 agonist (mirabegron) with lower cognitive risk
- MR formulation has fewer CNS and GI side effects than IR
- Transdermal patch has even fewer systemic side effects (bypasses first-pass metabolism and reduces active metabolite levels)
- Cognitive impairment: avoid in elderly with dementia or MCI (STOPP/START criteria)
- Sugarless gum/sweets for dry mouth
Contraindications
- Urinary retention
- Narrow-angle glaucoma
- Myasthenia gravis
- Severe GI motility disorders
- Toxic megacolon
Side effects
- Dry mouth (very common — anticholinergic)
- Constipation
- Blurred vision
- Urinary retention (paradoxical)
- Cognitive impairment (elderly — anticholinergic burden)
- Tachycardia
- Dry skin and flushing
- Drowsiness
Interactions
- Other antimuscarinics — additive effects (avoid combinations)
- Cholinesterase inhibitors (donepezil) — antagonistic (reduce dementia drug efficacy)
- Amantadine, antipsychotics — additive anticholinergic burden
Monitoring
- Urinary symptoms and residual volume
- Cognitive function (elderly)
- IOP (glaucoma risk)
- GI function
Reference: BNFc; BNF; NICE NG123 Urinary Incontinence; BNFc; STOPP/START criteria. Verify against your local formulary and the latest BNF before prescribing.
Related
Curated clinical cross-links plus same-class fallbacks.
Calculators