Impact of Bariatric Surgery on Medication Efficacy: an Analysis of World Health Organization Pharmacovigilance Data.

Bariatric surgery is the most effective treatment of severe obesity. However, this surgery can have an impact on the bioavailability and metabolism of oral drugs as it modifies absorption, intestinal, and hepatic metabolism, and efflux transporter activity. The clinical impact of such modifications often remains unknown. To investigate, we extracted and summarized all reports of changes in drug efficacy associated with bariatric surgery registered in the WHO pharmacovigilance database. We identified 165 drug reports affecting 128 patients. The majority involved gastric bypass surgery (77.3%). Most reports concerned drug ineffectiveness (74.7%). The most frequent modifications concerned psychotropic drugs with a reduction in efficacy. This study underlines the urgent need for more research to better characterize the impact of bariatric surgery on drug pharmacokinetics and clinical efficacy.