In 2001, when we had agitated patients in the emergency department, we’d give them intramuscular droperidol and everything would be fantastic. It also worked well for nausea and vomiting, and was a useful adjunct for headache treatment.
Explore This IssueACEP Now: Vol 38 – No 09 – September 2019
But then because of concerns related to prolongation of the QT interval on ECG, the threat of torsades de pointes, and persistent shortages of the drug, the U.S. Food and Drug Administration (FDA) published a widely criticized warning that recommended a screening ECG prior to dosing, telemetry for two to three hours following administration, and a contraindication for patients with a long QTc (with a cutoff at >440 ms for males, >450 ms for females).1 In short order, droperidol disappeared from hospitals in the United States, the United Kingdom, and many other places, despite the fact that other medications like haloperidol had the same theoretical risks and remained widely available. But now, injectable droperidol is back, courtesy of manufacturer American Regent. Much of the body of knowledge regarding the clinical use of droperidol has eroded over time, so here’s what you need to know:
Dosing and Benefits
First, droperidol at the 5–10 mg doses (intravenous [IV] or intramuscular [IM]) used for sedation and control of agitation is safe. Onset of action can be expected within 5–10 minutes IM, and a bit faster IV, though studies suggest full effects may not be apparent for up to 20–30 minutes, at which time redosing can be considered. IM haloperidol, on the other hand, works far more slowly than droperidol, often taking 20–30 minutes for onset. In fact, the main advantage of droperidol for agitated patients is precisely in those without IV access. IV haloperidol works fine for psychosis. But without an IV line in place, the delayed onset with IM haloperidol is not workable in the emergency department setting, which is why it is so often mixed with benzodiazepines (“5 and 2” just flies off the tongue; more on that later).
The FDA warning, which it bears noting has not been revised, uses 2.5 mg as its threshold for concern. But there is no good evidence to support this approach. True, some people who received droperidol have developed torsades but only after receiving absolutely gargantuan doses, totaling more than 300 mg. Droperidol’s cardiovascular safety is supported by a series of studies that found none of the more than 1,200 agitated patients who received the drug developed torsades (see Table 1).2-4 Some patients did exhibit prolongation of the QT interval, but a substantial proportion of patients had additional reasons for prolonged repolarization. Although these data were collected in emergency departments, studies in prehospital and anesthesia settings have added heft to the finding that sedating doses of droperidol cause neither clinically significant QT prolongation nor torsades. In short, droperidol is safe.