Esomeprazole Warfarin

While generally not of major concern, omeprazole may inhibit the metabolism of warfarin, diazepam, and phenytoin lansoprazole may decrease theophylline concentrations. Drug interactions with omeprazole are of particular concern in patients who are considered slow metabolizers, as are approximately 3% of the Caucasian population. Unfortunately, it is unclear which patients have the polymorphic gene variation that makes them slow metabolizers.17 The metabolism of esomeprazole may also be altered in patients with this polymorphic gene variation. Patients on potentially interacting drugs should be monitored for development of drug-related problems. 

ANTICOAGULANTS-ORAL PROTON PUMP INHIBITORS Possibly t anticoagulant effect when esomeprazole, lansoprazole or omeprazole is added to warfarin Uncertain at present. Omeprazole and lansoprazole are known to induce CYP1A2, which plays a role in activation of coumarins Monitor INR more closely. 1 dose may be required. If 10%, 20% or 30% over range, omit dose for 1, 2 or 3 days respectively consider i maintenance dose by 10%. Regular dosing of a proton pump inhibitor is preferable if affects INR significantly. Not reported with pantoprazole or rabeprazole... 

Clinically important, potentially hazardous interactions with aminophylline, amprenavir, antacids, carbamazepine, carmustine, chlorpheniramine, clarithromycin, efavirenz, esomeprazole, imatinib, indinavir, itraconazole, ketoconazole, MAO inhibitors, midazolam, modobemide, nelfinavir, phenytoin, sucralfate, warfarin... 

Esomeprazole is the S-isomer of omeprazole, and would be expeeted to behave similarly, see below. The manufaeturers say that esomeprazole 40 mg daily did not eause any clinically relevant effects on anticoagulant times in patients stabilised on warfarin, but a few isolated cases of raised INRs have been reported post-marketing. ... 

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