Background: The aim of this placebo-controlled double-blinded cross-over study was to investigate the antihyperalgesic effect of topical morphine and buprenorphine in the sunburn pain model.
Material and methods: The study was designed as a double-blind, placebo-controlled cross-over trial, separated into 2 parts each with 16 volunteers. In part A morphine dissolved in Ultrabas-ultrasic ointment at 3 concentrations (0.1, 0.2, 0.4%) and placebo ointment were applied to 4 UVB-induced erythemas on the thighs. In part B buprenorphine at 3 concentrations (0.01, 0.02 and 0.1%) and placebo dissolved in a gel for transcutaneous application, was applied to 4 erythemas on the thighs. Thermal and mechanical hyperalgesia were assessed in the respective erythema by standardized quantitative sensory testing and opioids were compared to the placebo.
Results: Neither morphine nor buprenorphine showed any significant reduction of hyperalgesia in comparison to the placebo.
Conclusion: The topical application of opioids in this form has no effect on inflamed skin.