Lithium toxicity following bariatric surgery

Lithium toxicity following Roux-en-Y gastric bypass: Mini review and illustrative case

Lithium is among the mainstays of treatment for bipolar disorder. Bariatric surgery can considerably change the oral bioavailability of drugs, particularly lithium. In this review, a 36-year-old male patient is described, who presented with lithium toxicity, including neurologic and gastric symptoms after undergoing Roux-en-Y gastric bypass. The mechanism of lithium toxicity is discussed; recommendations for clinicians regarding lithium use in postsurgical patients are provided; and previous case reports of lithium toxicity post-gastric bypass surgery are analyzed. Awareness and education of lithium absorption changes postbariatric surgery is essential for optimal patient care. Close clinical and drug concentration level monitoring is warranted.

Lamotrigine therapy in patients after bariatric surgery: Potentially hampered solubility and dissolution

Bariatric surgery is an effective treatment of obesity and related comorbidities. With surgery, the stomach undergoes major anatomical/physiological changes that may affect the oral exposure of drugs, especially marginally soluble weak bases, such as lamotrigine. The aim of this work was to study the solubility/dissolution of lamotrigine in conditions simulating the stomach before vs. after bariatric surgery. Lamotrigine solubility was studied in-vitro, as well as ex-vivo in gastric content aspirated from patients before vs. after bariatric surgery. We then compared the dissolution kinetics of various marketed lamotrigine products in pre- vs. post-operative stomach conditions, different in volume, pH, agitation strength and speed. Decreased lamotrigine solubility with increasing pH (from 1.37 ± 0.09 (pH = 1) to 0.22 ± 0.03 mg/mL (pH = 7)) was obtained. Twelve-fold higher lamotrigine solubility was revealed in gastric content aspirated before vs. after surgery (8.5 ± 0.7 and 0.7 ± 0.01 mg/mL, respectively). Dissolution studies showed that only the lowest dose (25 mg) fully dissolved in the post-surgery stomach conditions, while at higher doses, lamotrigine tablet dissolution was impaired. Neither fast-dissolving tablet, nor tablet crushing, helped resolving this problem. Based on these results, and given that dissolution of the drug dose governs the subsequent absorption, close monitoring of this essential drug is advised after bariatric surgery.