Topical difamilast for the treatment of mild-to-moderate atopic dermatitis.

Difamilast (also known as OPA-15406 or MM36) is a non-steroidal, highly selective inhibitor of phosphodiesterase 4 (PDE4). Its chemical name is N-[[2-[4-(difluoromethoxy)-3-propan-2-yloxyphenyl]-1,3-oxazol-4-yl]methyl]-2-ethoxybenzamide. The compound has a molecular formula of C23H24F2N2O5 and a molecular weight of 446.44 g/mol. In appearance, difamilast occurs as white crystals or crystalline powder. The compound is highly soluble in N-methylpyrrolidone, freely soluble in methanol and ethanol, and practically insoluble in water.