Rabeprazole is metabolized by the cytochrome P450 (CYP450) drug metabolizing enzyme system. Rabeprazole does not have clinically significant interactions with other drugs metabolized by the CYP450 system, such as warfarin, theophylline, diazepam and phenytoin.
Rabeprazole produces sustained inhibition of gastric acid secretion. An interaction with compounds which are dependent on gastric pH for absorption like ketoconazole may occur due to the magnitude of acid suppression observed with Rabeprazole. Therefore, patients may need to be monitored when such drugs are taken concomitantly with Rabeprazole. Co-administration of Rabeprazole and antacids produced no clinically relevant changes in plasma Rabeprazole concentrations.
While adverse interactions have not been reported in general clinical use, domperidone has the potential to interact with dopamine agonist (e.g. bromocriptine), antimuscarinics and opioid analgesics. It may also enhance the absorption of concomitantly administered drugs especially in cases of delayed gastric emptying.