RiteMED Omeprazole Drug Interactions

Injection: The potential for metabolic interactions between omeprazole and other drugs is very limited. However, as omeprazole inhibits hepatic microsomal drug metabolism (cytochrome P450 system) or that are highly extracted by the liver may be decreased during concurrent use with omeprazole. This effect may result in delayed elimination, increased blood concentrations of diazepam, phenytoin and anticoagulants such as warfarin (monitoring of blood concentrations, or prothrombin time for anticoagulants is recommended as a guide to dosage since dosage adjustment may be necessary during omeprazole therapy).
Omeprazole, by increasing gastric pH, has the potential to affect the bioavailability of any medication for which absorption is pH-dependent and also omeprazole may prevent the degradation of acid-labile drugs. Therefore, concurrent use of itraconazole and ketoconazole with omeprazole may result in reduced absorption of these drugs.
Omeprazole has no influence on any other relevant isoforms of CYP, as shown by the lack of metabolic interaction with substrates for CYP1A2 (caffeine, phenacetin, theophylline), CYP2C9 (S-warfarin, piroxicam, diclofenac and naproxen), CYP2D6 (metoprolol, propranolol), CYP2E1 (ethanol) and CYP3A (cyclosporin, lidocaine, quinidine, estradiol, erythromycin, budesonide).