['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.', '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.', 'Neither morphine nor buprenorphine showed any significant reduction of hyperalgesia in comparison to the placebo.'] Does [ Topical application of morphine and buprenorphine gel have no effect in the sunburn model ]?