Gastric Bypass Reduces Bioavailability of Azithromycin

Bariatric surgery can profoundly affect how the body absorbs medications – this issue, however, remains largely understudied.

In a paper, just published in the Journal of Antimicrobial Chemotherapy, we examine the effect of gastric bypass surgery, a procedure that circumvents the upper gut on the bioavailability (absorption) of azithromycin, a widely used treatment for community-acquired infections.

We performed single-dose pharmacokinetic studies in 14 female post-gastric bypass patients and 14 sex- and body mass index (BMI)-matched controls (mean age 44 years and BMI 36.4).

Azithromycin concentrations, following the administration of two 250 mg tablets were about 30% lower in gastric bypass patients compared with controls.

This finding suggests that there may be a substantial risk for treatment failure with this antibiotic in and clinicians should consider dose modification and/or closer clinical monitoring of gastric bypass patients receiving azithromycin.

AMS
Calgary, Alberta

Padwal RS, Ben-Eltriki M, Wang X, Langkaas LA, Sharma AM, Birch DW, Karmali S, & Brocks DR (2012). Effect of gastric bypass surgery on azithromycin oral bioavailability. The Journal of antimicrobial chemotherapy PMID: 22577100

.