The effects of omeprazole (20 mg once daily) or famotidine (40 mg once daily) on the pharmacokinetics of EVG and cobicistat were studied in HIV-negative subjects (n=11 per group).

When omeprazole was administered 2 hours prior to elvitegravir and cobicistat the AUC and Cmax of elvitegravir increased by 10% and 16%, but those of cobicistat decreased by 8% and 10%. Separating omeprazole and EVG and cobicistat by 12 h had no effect (<10% change) on the AUC or Cmax of elvitegravir or cobicistat. Administration of famotidine 12 h apart from elvitegravir and cobicistat had no effect (<10% change) on the AUC or Cmax of elvitegravir or cobicistat.

Similar results were observed in a separate study (n=16) of the simultaneous coadministration of famotidine with elvitegravir and cobicistat. No dosing restrictions are necessary on the administration of EVG and cobicistat with proton pump inhibitors.

Based on the available data, elvitegravir and cobicistat should be administered simultaneously with, and/or 12 hours after, dosing of H2 receptor antagonists.

Reference

1. Mathias A et al. Effect of acid reducing agents on the relative bioavailability and pharmacokinetics of cobicistat boosted elvitegravir. 12th International Workshop on Clinical Pharmacology of HIV Therapy, 13–15 April 2011, Miami. Poster abstract: P_13

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