Drug Interaction Report

GENERALLY AVOID: Coadministration with potent inducers of CYP450 2C19 and/or 3A4 may significantly decrease the plasma concentrations of omeprazole, which is primarily metabolized by these isoenzymes. In a study consisting of 12 healthy male subjects, administration of omeprazole in combination with St John's wort (300 mg three times daily for 14 days) decreased omeprazole peak plasma concentration (Cmax) and systemic exposure (AUC) in CYP450 2C19 poor metabolizers by 37.5% and 37.9%, respectively, and in extensive metabolizers by 49.6 % and 43.9%, respectively. The interaction is likely to also occur with esomeprazole, an enantiomer of omeprazole.

MANAGEMENT: The concomitant use of omeprazole or esomeprazole with St. John's wort or rifampin should generally be avoided.

GENERALLY AVOID: An isolated case report suggests that foods containing large amounts of tyramine may precipitate a hypertensive crisis in patients treated with St. John's wort. The mechanism of interaction is unknown, as St. John's wort is not thought to possess monoamine oxidase (MAO) inhibiting activity at concentrations achieved in vivo. The case patient was a 41-year-old man who had been taking St. John's wort for seven days prior to presentation at the emergency room with confusion and disorientation. The patient recalled last eating aged cheese and having a glass of red wine approximately 10 hours prior to admission. No other cause of delirium or hypertension could be identified. In addition, alcohol may potentiate some of the pharmacologic effects of St. John's wort. Use in combination may result in additive central nervous system depression and/or impairment of judgment, thinking, and psychomotor skills.

MANAGEMENT: Until further information is available, patients treated with St. John's wort should consider avoiding consumption of protein foods in which aging or breakdown of protein is used to increase flavor. These foods include cheese (particularly strong, aged or processed cheeses), sour cream, wine (particularly red wine), champagne, beer, pickled herring, anchovies, caviar, shrimp paste, liver (particularly chicken liver), dry sausage, figs, raisins, bananas, avocados, chocolate, soy sauce, bean curd, yogurt, papaya products, meat tenderizers, fava beans, protein extracts, and dietary supplements. Caffeine may also precipitate hypertensive crisis so its intake should be minimized as well. Patients should also be advised to avoid or limit consumption of alcohol.