Abstract
The objective of this study is to assess the pharmacokinetics of lidocaine penetration into tumor tissue during glioblastoma surgery. In-vitro studies of glioblastoma have demonstrated co-culture with lidocaine inhibits glioblastoma proliferation via inhibition of TRPM7 channels. TRPM7 is a transmembrane ion channel that modulates proliferation and migration in several human cancers. Scalp block with lidocaine during glioblastoma surgery has been associated with improved survival in human studies. Twelve patients were enrolled in this study. The study group received an intravenous bolus dose of 1.5 mg/kg IBW of lidocaine at induction of anesthesia followed by 2 mg/kg IBW/hr infusion of lidocaine. Craniotomy was performed in the standard fashion. A total of 3 fresh tumor specimens were collected hourly from each patient after confirmation of glioblastoma diagnosis by frozen section. Plasma samples were simultaneously collected for analysis. Lidocaine concentration was measured using mass spectroscopy. The maximum concentration of lidocaine (Cmax), time from bolus to maximum concentration (Tmax), and area under curve from 0-3 hours (AUC) were calculated for each patient. Patients were followed for survival and adverse events. The median tumor specimen Cmax, Tmax, and AUC values were 333 ng/dL (range 226-555), 179 min (range 126-211), and 20665 ng*min/dL (range 8003-55,426), respectively. Peak lidocaine concentration was reached in 6 of 12 cases. Median Cmax and Tmax for plasma samples were 1195 ng/dL (range 951-1475) and 191 min (range 156-211), respectively. Median overall survival was 308 days (range 74-413). Two grade 3 adverse events occurred which were deemed to be unlikely to be related to the study intervention. In conclusion, lidocaine infiltrates tumor tissue when administered intravenously during glioblastoma surgery. Concentrations do not reach levels previously demonstrated to inhibit tumor growth in in vitro studies (roughly 2*10(8) ng/dL lidocaine). Alternative mechanisms may explain previously observed improved outcomes with lidocaine administration in human studies.