Dosage & Administration
The recommended dose for tolterodine is 2 mg twice daily. In case of troublesome side effects the dose may be reduced from 2 mg to 1 mg twice daily.
The recommended total daily dose of tolterodine is 2 mg (1 mg b.i.d.) for patients with impaired renal function, impaired liver function, or receiving concomitant medication with potent CYP3A inhibitors, such as macrolide antibiotics (e.g. erythromycin and clarithromycin) or azole antifungal agents (e.g. ketoconazole, itraconazole and miconazole). After six months the need for further treatment should be considered.
Pharmacokinetic interactions are possible with other drugs metabolised by or inhibiting cytochrome P450 2D6 (CYP2D6) or CYP3A4. Concomitant treatment with fluoxetine does not result in a clinically significant interaction.
Ketoconazole, a potent inhibitor of CYP3A, significantly increased plasma concentrations of tolterodine when coadministered to poor metabolisers (i.e. persons devoid of CYP2D6 metabolic pathway).
Clinical studies have shown no interactions with warfarin or combined oral contraceptives (ethinyloestradiol or levonorgestrel).
Pregnancy & Lactation
There are no studies in pregnant women. Therefore, tolterodine should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
Use of tolterodine during lactation should be avoided since no data on excretion of the drug into breast milk in humans is available.