Pharmacokinetics of lidocaine and its active metabolites in patients with obesity undergoing laparoscopic bariatric surgery: A prospective clinical study

Purpose: Lidocaine is widely used in laparoscopic bariatric surgery for obese patients. However, the impact of obesity on the pharmacokinetics of lidocaine and its metabolites is still unclear. This study aimed to compare the pharmacokinetics of lidocaine and its active metabolites in patients with obesity and normal-weight patients after a single lidocaine intravenous administration during surgery. Methods: Sixty patients were enrolled in this study, including thirty patients with obesity undergoing laparoscopic sleeve gastrectomy and thirty normal-weight patients undergoing laparoscopic cholecystectomy. All patients were administered a single intravenous bolus of lidocaine (2%, 1.5 mg/kg) before the operation. Arterial blood samples were collected during the surgery to analyze the pharmacokinetics of lidocaine and its metabolites. The lidocaine-related adverse events (AEs) were recorded throughout the study. Results: : The obese patients showed a significantly higher peak time ( P = 0.008), half-life ( P <0.0001), and volume of distribution ( P <0.0001) of lidocaine compared to the normal-weight patients. Conversely, the lidocaine peak concentration ( P = 0.035), clearance ( P = 0.032), and elimination rate ( P <0.0001) were lower in the patients with obesity. The differences in the pharmacokinetics of lidocaine metabolites between the two groups were similar to those of lidocaine. No serious AEs related to lidocaine were reported. Conclusion: Obesity significantly affects the pharmacokinetics of lidocaine and its active metabolites, and administrating lidocaine intravenously based on adjusted body weight is safe and reasonable for obese patients. Trial registration ChiCTR2200064980, 25 October 2022