Tolterodine is a competitive, specific muscarinic receptor antagonist used primarily for the treatment of overactive bladder (OAB) syndrome. It acts on the detrusor muscle of the urinary bladder, reducing involuntary contractions and increasing bladder capacity. The 4mg strength is typically the extended-release (ER) formulation, designed for once-daily administration, offering smoother plasma concentrations and potentially improved tolerability compared to the immediate-release (IR) form.
Adult: 4mg once daily (Extended-Release formulation). The recommended starting dose for most patients is 4mg ER OD. For patients with significant CYP3A4 inhibitor use or poor tolerability, a dose of 2mg ER OD may be considered.
Note: Swallow the extended-release capsule or tablet whole with a glass of water. Do not crush, chew, or divide. Can be taken with or without food, preferably at the same time each day. Taking with food may minimize minor gastrointestinal upset.
Tolterodine is a competitive antagonist of muscarinic (M) acetylcholine receptors. In the treatment of overactive bladder, its primary effect is on the M2 and M3 receptor subtypes in the detrusor muscle of the urinary bladder. By blocking acetylcholine binding, it inhibits involuntary detrusor muscle contractions (detrusor overactivity), increases bladder capacity, and delays the initial desire to void, thereby reducing urinary frequency, urgency, and urge incontinence.
Pregnancy: Category C. Animal studies have shown adverse effects (embryolethality, reduced fetal weight). No adequate and well-controlled studies in pregnant women. Use only if the potential benefit justifies the potential risk to the fetus.
Driving: May cause dizziness, blurred vision, and somnolence. Patients should not drive or operate machinery until they know how tolterodine affects them, especially at initiation of therapy.
| Ketoconazole, Itraconazole, Voriconazole, Posaconazole | Potent CYP3A4 inhibitors. Increase tolterodine plasma concentration significantly. Contraindicated in patients with renal/hepatic impairment. In others, max dose 2mg ER. | Major |
| Clarithromycin, Erythromycin, Telithromycin | Moderate CYP3A4 inhibitors. May increase tolterodine levels. Use with caution; consider dose reduction. | Moderate |
| Fluoxetine, Paroxetine, Quinidine | Potent CYP2D6 inhibitors. May increase tolterodine levels and decrease active metabolite levels, altering net effect. Monitor. | Moderate |
| Other anticholinergics (e.g., oxybutynin, tricyclic antidepressants, first-gen antihistamines, phenothiazines) | Additive anticholinergic side effects (dry mouth, constipation, blurred vision, urinary retention, confusion). | Moderate |
| Metoclopramide | Tolterodine may antagonize the prokinetic effect of metoclopramide. | Moderate |
| Drugs that prolong QT interval (e.g., Class Ia/III antiarrhythmics, macrolides, some antipsychotics) | Additive risk of QT prolongation and cardiac arrhythmias. | Major |
Same composition (Tolterodine (4mg)), different brands: