Drugs with pH-Dependent Absorption Kinetics
PREVACID causes long-lasting inhibition of gastric acid secretion. PREVACID and other PPIs are likely to substantially decrease the systemic concentrations of the HIV protease inhibitor atazanavir, which is dependent upon the presence of gastric acid for absorption, and may result in a loss of therapeutic effect of atazanavir and the development of HIV resistance. Therefore, PREVACID and other PPIs should not be co-administered with atazanavir. [See Clinical Pharmacology]
It is theoretically possible that PREVACID and other PPIs may interfere with the absorption of other drugs where gastric pH is an important determinant of oral bioavailability (e.g., ampicillin esters, digoxin, iron salts, ketoconazole). [See Clinical Pharmacology]
In a study of healthy subjects, co-administration of single or multiple 60 mg doses of PREVACID and warfarin did not affect the pharmacokinetics of warfarin nor prothrombin time (see Clinical Pharmacology . However, there have been reports of increased INR and prothrombin time in patients receiving PPIs and warfarin concomitantly. Increases in INR and prothrombin time may lead to abnormal bleeding and even death. Patients treated with PPIs and warfarin concomitantly may need to be monitored for increases in INR and prothrombin time. [See Clinical Pharmacology]
A minor increase (10%) in the clearance of theophylline was observed following the administration of PREVACID concomitantly with theophylline. Although the magnitude of the effect on theophylline clearance is small, individual patients may require additional titration of their theophylline dosage when PREVACID is started or stopped to ensure clinically effective blood levels. [See Clinical Pharmacology]
For information on drug interactions for amoxicillin or clarithromycin, refer to their full prescribing information, DRUG INTERACTIONS sections.