Anticholinergic·Urology

Oxybutynin

Overactive bladder (OAB) with urge incontinence, neurogenic bladder

Authority requiredPBSANTICHOLINERGICDitropan, Oxytrol (patch)5 mg tablet+2

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At a glance

Max Dose

20 mg/day

Half-life

2-3 h

Caution: Anticholinergic

HIGH RISK

High risk: Dry Mouth

SEVERE

Cautions

Avoid / Cautions

Narrow-angle glaucoma, urinary retention, severe ulcerative colitis, myasthenia gravis. Pregnancy Category B3.

Where it stands

Rapid Summary

Overview

Potent antimuscarinic agent. Highly effective at relaxing the detrusor muscle of the bladder, but notorious for severe, intolerable systemic anticholinergic side effects.

Clinical Focus

High risk of severe cognitive impairment, delirium, and falls in the elderly. Highly lipophilic, crosses BBB easily.

Bottom Line

Oxybutynin is an effective anticholinergic for overactive bladder and urinary incontinence, but has the highest anticholinergic burden of its class causing dry mouth, constipation, and cognitive impairment in elderly.

Formulation & Access

Brand Names

Ditropan, Oxytrol (patch)

Oral Routes

Tablets (5 mg).

Parenteral

Transdermal patch.

Prescribing & PBS

Authority Required (PBS).

Indications & Use

Primary

PBSTGA

Overactive bladder (OAB) with urge incontinence, neurogenic bladder.

Clinical Place

Highly effective historically, but increasingly superseded by newer, bladder-selective agents (Solifenacin, Mirabegron) due to horrific side effects.

Quick reference

Class & Role

Anticholinergic — Potent antimuscarinic agent.

Route / Formulation

Tablets (5 mg). (Ditropan, Oxytrol (patch))

Usual Dose & Max

PO 5 mg BD to TDS. Max 20 mg/day.

Key Indication Doses

Overactive Bladder / Spasm: PO 5 mg BD to TDS. Max 20 mg/day. Transdermal Patch: Apply 1 patch (3.9 mg/day) Topical twice weekly. Elderly / Frail: Start at 2.5 mg BD. Monitor strictly for confusion.

Best Uses

Key Risks

Gastrointestinal: Severe dry mouth (causes poor compliance and dental decay), severe constipation. Neurological: Confusion, delirium, hallucinations, dizziness (especially in elderly). Ocular: Blurred vision, dry eyes. Genitourinary: Urinary retention (can paralyze the bladder *too* much).

Key Interactions

Additive anticholinergic burden with TCAs, antipsychotics, and antihistamines (leads to frank delirium and bowel impaction). Antagonises prokinetics like Metoclopramide.

Monitoring

Monitor bowel chart (constipation) and assess cognition daily in older adults. Perform bladder scans if retention is suspected.

Clinical Pearl

The severe dry mouth is actually caused by the primary liver metabolite of Oxybutynin. Using the transdermal patch avoids first-pass metabolism, radically reducing dry mouth while maintaining bladder efficacy.

Access

Authority requiredDitropan, Oxytrol (patch)5 mg tablet

Brand: Ditropan, Oxytrol (patch)
PBS status: Authority required
Formulation: Tablets (5 mg).

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