The effect of 50% glycolic acid on the percutaneous absorption of eutectic mixture of local anesthetics (EMLA): a study of the electrofulguration-induced pain

Abstract

EMLA has a slow onset due to its limited percutaneous absorption into an intact skin, while Glycolic acid (GA) has been known to have the capability of disrupting the skin barrier function. To the best of our knowledge, the effect of 50% GA on the percutaneous absorption of EMLA has not been studied previously. The study used a two-step randomized double blind controlled trial involving 20 healthy subjects each. The first step compared the pain intensity upon applying GA and placebo for 4 minutes prior to EMLA occlusive application over time. Based on findings made in the first step, second step observation focused on the effect of occlusion on EMLA percutaneous absorption after GA application in minute 30 and 45. A second of 20 mA electrofulguration induced the pain, while modified Verbal Rating Scale (VRS) measured the pain intensity. Significant VRS difference (P < 0.05) between GA and placebo group was found in minute 15, 20, 30 and 45. However, no significant VRS difference was found after minute 60 (P = 0.420). Adequate cutaneous analgesia was achieved in minute 30 in the treatment (GA) group and in minute 45 in the placebo. There was no significant VRS difference between the occlusive and non-occlusive group in minute 30 (P = 0.214) and minute 45 (P = 0.309). Administering 50% GA prior to EMLA application enhances percutaneous absorption of EMLA, which accelerates the onset of adequate cutaneous analgesia, even without using an occlusive dressing.