Droperidol

Discovered at Janssen Pharmaceutica in 1961, droperidol is a butyrophenone which acts as a potent D₂ (dopamine receptor) antagonist with some histamine and serotonin antagonist activity.

It has a central antiemetic action and effectively prevents postoperative nausea and vomiting in adults using doses as low as 0.625 mg. For treatment of nausea and vomiting, droperidol and ondansetron are equally effective; droperidol is more effective than metoclopramide.

It is used as a sedative given as an intramuscular injection with doses ranging from 5 to 10 mg for acute agitation.

Some practitioners recommend the use of 0.5 mg to 1 mg intravenously for the treatment of vertigo in an otherwise healthy elderly patients who have not responded to Epley maneuvers.

In 2001, the FDA changed the labeling requirements for droperidol injection to include a Black Box Warning, citing concerns of QT prolongation and torsades de pointes. The evidence for this is disputed, with 9 reported cases of torsades in 30 years and all of those having received doses in excess of 5 mg. QT prolongation is a dose-related effect, and it appears that droperidol is not a significant risk in low doses. A study in 2015 showed that droperidol is relatively safe and effective for the management of violent and aggressive adult patients in hospital emergency departments in doses of 10mg and above and that there was no increased risk of QT prolongation and torsades de pointes.

Dysphoria, sedation, hypotension resulting from peripheral alpha adrenoceptor blockade, prolongation of QT interval which can lead to torsades de pointes, and extrapyramidal side effects such as dystonic reactions/neuroleptic malignant syndrome.