Lansoprazole is hepatically metabolized and studies indicate that it is a weak inducer of cytochrome P-450. Accordingly, there is the possibility of interaction with drugs which are metabolized by the liver. In particular, caution should be exercised when oral contraceptives and preparations eg, phenytoin, carbamazepine, theophylline or warfarin are taken concomitantly with the administration of lansoprazole.
No clinical significant effects on NSAIDs or diazepam have been found.
Antacids and sucralfate may reduce the bioavailability of lansoprazole and should therefore not be taken within an hour of lansoprazole.