<p>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.<br />
<br />
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).<br />
<br />
Clinical studies have shown no interactions with warfarin or combined oral contraceptives (ethinyloestradiol or levonorgestrel).</p>