Diazepam with proton pump inhibitors

Omeprazole is a proton pump inhibitor. Headache, skin rash, and diarrhea have all been recorded by adverse event registries sufficiently often to suggest causal relations (1). Omeprazole is a modest inhibitor of CYP isoforms. Interactions are less likely than with cimetidine and are probably of no practical importance. However, omeprazole reduces the absorption of drugs that require a low gastric pH (ketoconazole, iron salts, ampicilhn) and can inhibit the hepatic clearance of some drugs (diazepam, warfarin, phenytoin) (2). 

C. Toyoki, T. Comparison of the interaction potential of a new proton pump inhibitor, E3810, versus omeprazole with diazepam in extensive and poor metabolizers of S-mephenytoin 4 -hydroxylation. Clin.Pharmacol.Ther., 1995, 58, 155-164... 

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