Tolterodiin

Tolterodiin, more commonly spelled tolterodine, is a medication used to treat symptoms of overactive bladder, including urinary urgency, frequency, and urge incontinence. It belongs to the class of antimuscarinic agents and works by blocking muscarinic receptors in the bladder, which reduces involuntary detrusor contractions.

Administration typically involves oral dosing. Immediate-release tolterodine is usually given as 2 mg twice daily, while an extended-release formulation is given as 4 mg once daily. Dosing may be adjusted for age, liver function, or interactions with other medicines.

Pharmacology and metabolism: Tolterodine acts as a competitive antagonist at muscarinic receptors, with activity at several subtypes, and is thought to reduce bladder contractions mainly through M3 receptor effects. It is extensively metabolized in the liver to an active metabolite, 5-hydroxymethyl tolterodine, contributing to the therapeutic effect. Metabolism occurs mainly via CYP2D6, with CYP3A4 also involved; genetic differences in CYP2D6 can influence drug levels and response. Both the parent drug and the metabolite are excreted through the urine and feces.

Contraindications and cautions: Tolterodiin should not be used in people with urinary retention, uncontrolled narrow-angle glaucoma, or severe hepatic impairment. Caution is advised in elderly patients and those with myasthenia gravis or moderate renal impairment.

Adverse effects and interactions: Common side effects include dry mouth, constipation, dizziness, and headache. Other possible effects are blurred vision, fatigue, and urinary retention. The drug can interact with other antimuscarinic agents and with drugs that strongly inhibit or induce CYP2D6 or CYP3A4, potentially altering drug levels.

Pregnancy and breastfeeding: Data are limited; tolterodine should be used during pregnancy only if clearly needed. It may pass into breast milk.

Branding: Tolterodine is marketed as Detrol and Detrol LA in many regions; generic tolterodine is also available.