Medetomidine is an imidazole derivative that acts as a selective agonist of α2-adrenoceptors (Ki = 1.08 nM vs. 1750 nM for α1-adrenoceptors). Medetomidine is a mixture of D and L isomers, with the D form, known as dexmedetomidine , described as the active form. Through its effect on α2-adrenoceptors, medetomidine has sedative, antinociceptive, analgesic, and hypothermic actions. Its effects on pain are additive or synergistic with fentanyl-type opioids. The effects of medetomidine are effectively countered by α2-adrenoceptor antagonists, like atipamezole. Selective α2-adrenoceptor agonists, including medetomidine, have anesthetic sparing properties, greatly reducing the dose of anesthetic required following premedication with the α2-adrenoceptor agonist.
