modafinil and omeprazole: label evidence and limits

The modafinil label names omeprazole among CYP2C19 substrates whose elimination may slow and exposure may increase during coadministration.

Which products this evidence covers

Oral modafinil tablets.

What this finding does and does not establish

The label discusses possible clinician-directed dose adjustment. An omeprazole study elsewhere in this label used armodafinil; its numerical result should not be attributed to a modafinil study.

Supporting label passage

Elimination of drugs that are substrates for CYP2C19 (e.g., phenytoin, diazepam, propranolol, omeprazole, and clomipramine) may be prolonged by modafinil tablets via inhibition of metabolic enzymes, with resultant higher systemic exposure. In individuals deficient in the CYP2D6 enzyme, the levels of CYP2D6 substrates which have ancillary routes of elimination through CYP2C19, such as tricyclic antidepressants and selective serotonin reuptake inhibitors, may be increased by co-administration of modafinil tablets. Dose adjustments of these drugs and other drugs that are substrates for CYP2C19 may be necessary when used concomitantly with modafinil tablets [see Clinical Pharmacology (12.3) ].

Read the product label on DailyMed. Section: 7 Drug Interactions — CYP2C19 substrates. Compared label version 14, dated 2026-09-03.

How this brief was prepared

This brief uses an AI-assisted source comparison dated 2026-10-16. The label version and supporting passage were checked again on 2026-10-25. Independent clinical review has not been recorded. The comparison does not validate CDI's severity category or determine individual treatment.

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