Adrenergic alpha2-Antagonists

Alpha-2 adrenoceptors inhibit adenylyl cyclase through Gi/o, suppress voltage-gated calcium channels and damp presynaptic noradrenaline release. Drugs in this class occupy the receptor without activating it and so lift that inhibition. The FDA-approved veterinary label for atipamezole describes it as a potent alpha-2 antagonist which selectively and competitively inhibits alpha-2 adrenergic receptors, the result in the dog being rapid recovery from the sedative and analgesic effects produced by dexmedetomidine or medetomidine. A drug belongs here because it blocks an alpha-2 receptor, which is why atipamezole, the reversal agent for those two sedatives, sits in this class. As MED-RT populates it the class holds only four ingredients - atipamezole, celiprolol, mianserin and mirtazapine - and atipamezole is the only reversal agent among them.