<p>Esomeprazole is extensively metabolized in the liver by CYP2C19 and CYP3A4. In vitro and in vivo studies have shown that Esomeprazole is not likely to inhibit CYPs 1A2, 2A6, 2C9, 2D6, 2E1 and 3A4. No clinically relevant interactions with drugs metabolized by these CYP enzymes would be expected. Drug interaction studies have shown that Esomeprazole does not have any clinically significant interactions with phenytoin, warfarin, quinidine, clarithromycin or amoxicillin.<br />
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Esomeprazole may potentially interfere with CYP2C19, the major Esomeprazole metabolizing enzyme. Co-administration of Esomeprazole 30 mg anddiazepam, a CYP2C19 substrate has resulted in a 45% decrease in clearance of diazepam. Increased plasma levels of diazepam have been observed 12 hours after dosing and onwards. Esomeprazole inhibits gastric acid secretion. Therefore, Esomeprazole may interfere with the absorption of drugs where gastric pH is an important determinant of bioavailability (e.g., ketoconazole, iron salts and digoxin).<br />
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Co-administration of oral contraceptives, diazepam, phenytoin, or quinidine do not seem to change the pharmacokinetic profile of Esomeprazole.<br />
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Combination Therapy with Clarithromycin: Co-administration of esomeprazole, clarithromycin, and amoxicillin has resulted in increases in the plasma levels of esomeprazole and 14-hydroxyclarithromycin.</p>