A comparative study of transdermal 10% lidocaine gel with and without glycyrrhetinic acid monohemiphthalate disodium for pain reduction at venous cannulation

: The clinical benefits of transdermal 10% lidocaine base gels with and without 3% glycyrrhetinic acid monohemiphthalate disodium (GAMHPh) for reduction of pain at venous cannulation were compared in a randomized, double-blind fashion in 24 surgical patients. After about 60 min of occlusive transdermal application, the mean pinprick pain score (1.3 +/- 1.5) in the GAMHPh group (n = 12), graded by noting the number of painful pinpricks out of five, was significantly less than that (2.5 +/- 1.7) in the control group (n = 12) (P less than 0.05). Twelve patients (eight in the GAMHPh group and four in the control group) who had a pinprick score less than 1 underwent venous cannulation without intradermal injection of a local anesthetic. The pain score at venipuncture, graded by the patients on a scale of 5, was significantly less in the GAMHPh group than that in the control group (1.9 +/- 1.1 vs 3.3 +/- 1.0, P less than 0.05). Erythema observed in 8 of the 24 patients was the only adverse local reaction. Addition of 3% GAMHPh to the lidocaine gel is useful in promoting transdermal lidocaine absorption.