The study will consist of 3 parts. Part A of the study will assess the feasibility of different cantharidin blister induction/sampling timepoints (challenge options) ranging from 16/16 hours to 48/48 hours, including the ability to evaluate the acute and resolving phase of acute inflammation. In Part A, 4 to 8 healthy male volunteers will be included. This will be followed by Part B (in up to 12 subjects), aimed to select the optimum challenge option based on the reproducibility of read-outs across two challenge sessions. This option will be applied in Part C in up to 24 subjects in order to evaluate the utility of the assay to demonstrate anti-inflammatory effects of a standard macrolide (azithromycin). Part C is designed as a double-blind, placebo-controlled, parallel group trial. Following the first cantharidin challenge and blister evaluation, subjects will be randomised in a 1:1 ratio to receive azithromycin or placebo. Skin blister induction and assessment will be repeated immediately after treatment completion and, potentially, approximately 3 weeks later. The inflammatory response to cantharidin and its modulation by azithromycin will be evaluated by total and differential cell counts in blister fluid, monocyte/macrophage phenotyping and the measurement of selected inflammation mediators in blister fluid and serum.
The purpose of this study is to investigate the utility of the cantharidin-induced skin blister assay for evaluation of the anti-inflammatory effects of macrolides in healthy male volunteers.