Abstract
A local anesthetic preparation to be applied on skin surface, 7% lidocaine cream, was prepared and was stored for one year under a room temperature (25±2°C) to test the stability. The appearance was visually inspected, lidocaine content was determined by high-performance liquid chromatography (HPLC), and water content was measured according to the Karl Fisher method described in the Japanese Pharmacopeia.The transdermal absorption and the anesthetic effect were also compared between the 7% lidocaine cream and EMLA cream (ASTRA) which is used in Europe.The transdermal absorption was estimated from the remaining drug in the cream one hour after application. The anesthetic effect was assessed according to the pinprick method.
Little changes in both lidocaine content and water content of the 7% lidocaine cream were observed one year after the preparation, which proved its satisfactory stability.Although it was estimated that the amount of drug absorbed was smaller with 7% lidocaine cream than that with EMLA cream, both creams had an almost equivalent anesthetic effect.
