Is Dosage Adjustment Based on Age Necessary for Intravenous Lidocaine in Patients Undergoing General Anesthesia: A Prospective Multi-Arm Comparative Study.

It remains unclear whether dosage adjustment of intravenous lidocaine is necessary during general anesthesia for elderly patients over 75 years old. This study aimed to investigate the effects of age on the pharmacokinetics (PK) and safety of intravenous lidocaine in patients undergoing general anesthesia. A total of 599 plasma samples were collected from 76 general anesthesia patients across three age groups: 18-64, 65-74, and ≥ 75 years. Lidocaine was administered intravenously at a dose of 1.5 mg/kg for the 18-64 and 65-74 years groups, while the dose was adjusted to 1.0 mg/kg for the ≥ 75 years group. The plasma concentrations of lidocaine and its active metabolites were measured using a validated ultra-performance liquid chromatography-tandem mass spectrometry assay, and the data were analyzed using a noncompartmental analysis. The results revealed no significant age-related differences in the PK of lidocaine and its metabolites. Among the three age groups, over 90 % of patient achieved a lidocaine concentration within a safe and effective range when the dosage was normalized to 1.5 mg/kg. In conclusion, age-based dosage adjustment was unnecessary for intravenous lidocaine in patients below 86 years undergoing general anesthesia.