Time to retire haloperidol?

Second-generation antipsychotics. The SGAs available in IM formulations, such as aripiprazole, olanzapine, and ziprasidone, have been shown to be at least as effective as haloperidol for the treatment of acute agitation (in 2015, the short-acting injectable formulation of aripiprazole was discontinued in the United States independent of safety or efficacy issues⁵³). A review of RCTs examining IM SGAs for the treatment of agitation concluded that the number needed to treat for response compared with placebo was 5 for aripiprazole, 3 for olanzapine, and 3 for ziprasidone.⁵⁴ In terms of safety, a meta-analysis of studies examining IM medications for agitation confirmed that the risk of acute EPS, including dystonia, akathisia, and parkinsonism, is significantly lower with SGAs compared with haloperidol.⁵⁵ An RCT comparing IM ziprasidone with haloperidol found equivalently modest effects on QTc prolongation.⁵⁶ Therefore, SGAs are an obvious and evidence-based option for replacing haloperidol as a treatment for acute agitation.

Unfortunately, for clinicians hoping to replace haloperidol within a multiple-medication IM “cocktail,” there have been no published controlled trials of SGAs combined with benzodiazepines. Although a short report indicated that aripiprazole and lorazepam are chemically compatible to be combined within a single injection,⁵⁷ the package insert for aripiprazole warns that “If parenteral benzodiazepine therapy is deemed necessary in addition to ABILIFY injection treatment, patients should be monitored for excessive sedation and for orthostatic hypotension.”⁵⁸ The package insert for olanzapine likewise lists the combination of lorazepam and olanzapine as a drug interaction that can potentiate sedation, and the manufacturer issued specific warnings about parenteral combination.^59,60 A single published case of significant hypotension with combined IM olanzapine and lorazepam,⁶⁰ together with the fact that IM olanzapine can cause hypotension by itself,⁶¹ has discouraged the coadministration of these medications. Nonetheless, the combination is used in some emergency settings, with several retro­spective studies failing to provide evidence of hypotension or respiratory depression as adverse effects.^62-64

Droperidol. Droperidol was formerly a popular choice for managing acute agitation, with evidence from RCTs that droperidol, 5 mg, can improve symptoms significantly faster than either haloperidol, 5 mg, or lorazepam, 2 mg, and is absorbed just as rapidly whether administered IV or IM.^65-67 However, a 2001 FDA black-box warning about QTc prolongation included recommendations that a screening electrocardiogram should be obtained before administering droperidol. This action greatly curtailed the use of droperidol, and for some time, it was not marketed or available in the United States.

Over the past decade, however, droperidol has returned to the US market⁶⁸ and its IV and IM usage has been revitalized for managing patients with agitation within or en route to the ED. Studies have demonstrated droperidol efficacy comparable to midazolam, ziprasidone, or olanzapine, as well as effectiveness as an IV adjunct to midazolam.^69-71 In contrast to the FDA black-box warning, retrospective studies and RCTs of both IV and IM droperidol suggest that QTc prolongation and torsades de pointes are rare events that do not occur any more frequently than they do with haloperidol, even at doses >10 mg.^72,73 However, in studies involving patients with drug intoxication and treatment with multiple medications, oversedation to the point of needing rescue intervention was reported. In an emergency setting where these issues are relatively easily managed, such risks may be better tolerated than in psychiatric settings.

With earlier studies examining the use of droperidol in an acute psychiatric setting that reported a more rapid onset of action than haloperidol,^65-67 a 2016 Cochrane review concluded that there was high-quality evidence to support droperidol’s use for psychosis-induced agitation.⁷⁴ However, a 2015 RCT comparing IM droperidol, 10 mg, to haloperidol, 10 mg, found equivalent efficacy and response times (with maximal response occurring within 2 hours) and concluded that droperidol had no advantage over haloperidol.⁷⁵ Because none of the clinical trials that evaluated droperidol have included assessments for EPS, its risk of akathisia remains uncertain.

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