| Indication | Droperidol is ssed to produce tranquilization and to reduce the incidence of nausea and vomiting in surgical and diagnostic procedures. |
| Pharmacodynamics | Droperidol produces marked tranquilization and sedation. It allays apprehension and provides a state of mental detachment and indifference while maintaining a state of reflex alertness. Droperidol produces an antiemetic effect as evidenced by the antagonism of apomorphine in dogs. It lowers the incidence of nausea and vomiting during surgical procedures and provides antiemetic protection in the postoperative period. Droperidol potentiates other CNS depressants. It produces mild alpha-adrenergic blockade, peripheral vascular dilatation and reduction of the pressor effect of epinephrine. It can produce hypotension and decreased peripheral vascular resistance and may decrease pulmonary arterial pressure (particularly if it is abnormally high). It may reduce the incidence of epinephrine-induced arrhythmias, but it does not prevent other cardiac arrhythmias. |
| Mechanism of action | The exact mechanism of action is unknown, however, droperidol causes a CNS depression at subcortical levels of the brain, midbrain, and brainstem reticular formation. It may antagonize the actions of glutamic acid within the extrapyramidal system. It may also inhibit cathecolamine receptors and the reuptake of neurotransmiters and has strong central antidopaminergic action and weak central anticholinergic action. It can also produce ganglionic blockade and reduced affective response. The main actions seem to stem from its potent Dopamine(2) receptor antagonism with minor antagonistic effects on alpha-1 adrenergic receptors as well. |
| Absorption | Completely absorbed following intramuscular administration. |
| Volume of distribution | Not Available |
| Protein binding | Not Available |
| Metabolism | Extensively metabolized. |
| Route of elimination | Not Available |
| Half life | Biphasic distribution. The rapid distribution phase is 1.4 ± 0.5 minutes and the slower distribution phase is 14.3 ± 6.5 minutes. Elimination half-life in adults is 134 ± 13 minutes and may be increased in geriatric patients. In children, it is 101.5 ± 26.4 minutes. |
| Clearance | Not Available |
| Toxicity | The intravenous LD50 of droperidol is 20-43 mg/kg in mice; 30 mg/kg in rats; 25 mg/kg in dogs and 11-13 mg/kg in rabbits. The intramuscular LD50 of droperidol is 195 mg/kg in mice, 104-110 mg/kg in rats; 97 mg/kg in rabbits and 200 mg/kg in guinea pigs. The manifestations of droperidol overdosage are an extension of its pharmacologic actions. |