Pharmacology · Overactive bladder agents
Tolterodine !
An antimuscarinic for overactive bladder whose active metabolite is made by CYP2D6, so genetics and interacting drugs change its levels.
Updated 2026-11-01
No structure of tolterodine bound to its receptor exists. The figure shows tiotropium, another muscarinic antagonist, in the acetylcholine pocket of the rat M3 receptor, the subtype that contracts the bladder; the pocket is nearly identical in the human receptor.
Mechanism of action
Tolterodine is a competitive antagonist of acetylcholine at muscarinic receptors. In the liver, CYP2D6 turns it into 5-hydroxymethyl tolterodine (5-HMT), which is just as active. Bladder contraction and salivation are both muscarinic, but in studies it showed some selectivity for the bladder over the salivary glands.
- CYP2D6 converts it to an equally active metabolite
- Both block muscarinic receptors of the detrusor
- Urgent contractions decrease
Pharmacokinetics
- Metabolism
- Liver CYP2D6 forms the active 5-HMT; in poor metabolizers CYP3A4 takes over and tolterodine itself rises
- Elimination
- Clearance is much lower in cirrhosis and altered in severe kidney disease, so lower doses are used
Indications
- Overactive bladder with urge incontinence, urgency and frequency Overactive bladder and urge incontinence →
Adverse effects
Common
- Dry mouth (the most common reason to stop)
- Headache
- Constipation
- Abdominal pain
- Dizziness and drowsiness
Contraindications
- Urinary retention
- Gastric retention
- Uncontrolled narrow-angle glaucoma
- Hypersensitivity to tolterodine or fesoterodine
Key interactions
- Fluoxetine and other strong CYP2D6 inhibitors
- Tolterodine levels rose about fivefold with fluoxetine
- Strong CYP3A4 inhibitors (ketoconazole, itraconazole, clarithromycin, ritonavir)
- Higher levels; a lower dose is used
- Other anticholinergic drugs
- More dry mouth, constipation, blurred vision and drowsiness
What is monitored
- Liver and kidney function before choosing the dose
- Mental status and drowsiness
- ECG if there is QT risk
Administration and safety
- Extended-release capsules are swallowed whole
Nursing care
- Review other medicines for CYP2D6 and CYP3A4 inhibitors
- Warn about driving if dizzy or drowsy
- Use caution in myasthenia gravis
Pregnancy and breastfeeding
No human data in pregnancy; animal studies at usual exposures did not show harm.
Test yourself
Think of the answer, then tap the question to see it.
Which enzyme forms tolterodine's active metabolite?
CYP2D6, which makes 5-hydroxymethyl tolterodine.
Why do CYP2D6 poor metabolizers need attention with tolterodine?
Tolterodine itself accumulates and the QT effect is more pronounced.
Hypersensitivity to which related drug is also a contraindication?
Fesoterodine, which is converted to the same active metabolite.
Related drugs
Related conditions
← Back to the class: Overactive bladder agents
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - TOLTERODINE TARTRATE- tolterodine capsule, extended release (DailyMed (U.S. National Library of Medicine), 2026); Tolterodine: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 11 (McGraw Hill, 2023).
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Representative model, for educational purposes only.