Drug reference

Oxybutynin

Antimuscarinic · Urinary Antispasmodic

Also known as oxybutynin hydrochloride, Immediate release oxybutynin, Transdermal oxybutynin, extended release formulation of oxybutynin hydrochloride

AntimuscarinicUrinary Antispasmodic

CDSCO approved

EXCRETION

—

not curated

INTERACTIONS

4 major

SEVERE in our sources

PREGNANCY

—

not curated

Top interactionssee all 12 →

Potassium ChlorideSevereDatabaseDDInter
Potassium CitrateSevereDatabaseDDInter
TopiramateSevereDatabaseDDInter
ZonisamideSevereDatabaseDDInter

Mechanism

Oxybutynin acts as an anticholinergic and antimuscarinic drug. Its therapeutic effects in conditions like urgency incontinence and overactive bladder are achieved by blocking muscarinic receptors, thereby reducing bladder contractions.

Indications

Urgency incontinence (for women who have trialled bladder training, where frequency is a problem and symptoms persist)Nocturnal enuresis associated with daytime symptoms (overactive bladder) (unlicensed indication)Overactive bladder disordersEnuresisNeurogenic bladderDetrusor instability (urinary frequency and urge incontinence)Post-prostatectomy vasical spasmSpina bifidaNocturnal enuresis

Dosing

Adult: Immediate release oxybutynin hydrochloride can be used first-line for urgency incontinence. The lowest dose should be used and titrated upwards if necessary. Transdermal oxybutynin hydrochloride may be used in those unable to tolerate oral treatment.
Pediatric: For nocturnal enuresis associated with daytime symptoms (overactive bladder) (unlicensed indication), can be managed under specialist supervision. Treatment should be continued for 3 months; the course can be repeated if necessary.
Hepatic adjustment: Dose should be reduced in patients being treated with inhibitors of CYP3A4.
Geriatric: Immediate release oxybutynin should not be used in frail, older women at risk of sudden deterioration in their physical or mental health. For women over 75 years of age, treatment should be reviewed every 6 months.

Pharmacokinetics

Bioavailability

1.6–10.9%

Protein binding

—

Metabolism

Metabolized by enteric and hepatic CYP3A4

Excretion

<1%

Contraindications

Frail, older women at risk of sudden deterioration in their physical or mental health (for immediate release oxybutynin)
Cognitive impairment (when considering anticholinergic medicine)
Poor bladder emptying (when considering anticholinergic medicine)
Urinary tract obstruction
GI obstruction
Uncontrolled angle-closure glaucoma
Benign prostatic hyperplasia (use with extreme caution)

Side effects

Common

High incidence of antimuscarinic side effectsXerostomiaBlurred visionConstipationGastrointestinal discomfortDrowsinessDizzinessConfusionAnticholinergic side effects (common after oral dosing, e.g., dry mouth)