Droperidol (Dehydrobenzperidol) is a Dopamine-2 Receptor Antagonist. The mechanism of action of droperidol is as a Dopamine D2 Antagonist.

Droperidol has a dual effect on repolarization, prolonging the development of EADs and the subsequent triggering of activity in rabbit Purkinje fibers at low concentrations. In rabbit Purkinje fibers stimulated with 60 pulses/min, 0.01 mM-0.3 mM Droperidol increased action potential duration (APD) in a dose-dependent manner without altering other parameters.1 mM-3 mM Droperidol resulted in a reversal of the prolongation effect in rabbit Purkinje fibers.10 mM- 30 mM Droperidol produced a shortening of the APD at 50% repolarization, accompanied by significant reductions in Vmax, action potential amplitude, and resting membrane potential in rabbit Purkinje fibers. A single dose of 3 mg/kg Droperidol not only dose-dependently reduced activity and rearing frequency in the open-field experiment, but also reduced the Apomorphine effect in rats.Droperidol (3 mg/kg, long-term administration) induced significant tolerance to all activity parameters recorded in the rat open field.

Droperidol has been shown to block potassium efflux from the myocardium of isolated animal ventricular myocytes, resulting in a dose-dependent delay in repolarization.Droperidol also induces early depolarization of Purkinje fibers in isolated animals.Droperidol produces mild alpha-adrenergic blockade and peripheral vasodilation.