Solitor 5 Drug Interactions

Drugs Metabolized by Cytochrome P450: Pharmacokinetic interactions: in vitro studies have demonstrated that at therapeutic concentrations, solifenacin does not inhibit CYP1A1/2, 2C9, 2C19, 2D6, or 3A4 derived from human liver microsomes. Therefore, solifenacin succinate is unlikely to alter the clearance of drugs metabolized by these CYP enzymes.
CYP3A4 Inhibitors: Solifenacin is metabolized by CYP3A4. Simultaneous administration of ketoconazole (200 mg/day), a potent CYP3A4 inhibitor, resulted in a two-fold increase of the AUC of solifenacin, while ketoconazole at a dose of 400 mg/day resulted in a threefold increase of the AUC of solifenacin. Therefore, the maximum dose of solifenacin succinate should be restricted to 5 mg, when used simultaneously with ketoconazole or therapeutic doses of other potent CYP3A4 inhibitors (e.g. ritonavir, nelfinavir, itraconazole).
Oral Contraceptives: Intake of solifenacin succinate showed no pharmacokinetic interaction of solifenacin on combined oral contraceptives (ethinylestradiol/levonorgestrel both CYP34A substrates).
Warfarin: Intake of solifenacin succinate did not alter the pharmacokinetics of R-warfarin (substrate of CYP34A) or S-warfarin (substrate of CYP2C9) or their effect on prothrombin time.
Digoxin: Intake of solifenacin succinate showed no effect on the pharmacokinetics of digoxin (0.125 mg/day) in healthy subjects.