Varying Lamotrigine Concentrations in Patients Following One Anastomosis Gastric Bypass Surgery: A Case Series

<b>Objectives:</b> Bariatric surgery, the most effective treatment for obesity and type 2 diabetes, may alter the absorption and overall bioavailability of orally administered drugs. In this case series, we present three patients undergoing one-anastomosis gastric bypass (OAGB) and their treatment with the anticonvulsant and mood stabilizer lamotrigine. <b>Key Findings:</b> Various mechanisms may be involved in the changes in lamotrigine blood levels following OAGB; some may lead to increased drug exposure, while others to its decrease. It was found that low and insufficient (case 1), higher (case 3), or unchanged (case 2) lamotrigine plasma levels are all possible after the surgery. <b>Conclusion:</b> This case series shows the complexity of drug treatment after bariatric surgery. The potentially large variability among patients in the effect of the surgery on the bioavailability of lamotrigine, a highly prescribed, life-saving medication, highlights the special care that must be taken with post-bariatric pharmacotherapy in general, and epilepsy treatment in particular.