The antidopaminergic class of antiemetics, which includes drugs such as droperidol, haloperidol, and amisulpride, offers effective options for the prophylaxis of postoperative nausea and vomiting (PONV). Low doses of droperidol (1.25 mg IV) and haloperidol have been shown to be as effective as ondansetron in preventing PONV, albeit with an increased risk of sedation. Despite the efficacy of droperidol, its use in the United States has declined significantly following a "black box" warning issued by the FDA in 2001 due to concerns over sudden cardiac death. However, at the doses recommended for PONV prophylaxis, the risk of adverse cardiac events remains very low. Both droperidol and haloperidol can cause an increase in the QT interval, similar to ondansetron, but combining them with ondansetron does not result in additional QT prolongation. Patients at increased risk of QT prolongation should avoid butyrophenones.
Haloperidol and droperidol are typically given as a single intravenous (IV) dose towards the end of surgery, although haloperidol can also be administered orally or intramuscularly (IM). These medications are not recommended for POV prophylaxis in children. Following the administration of droperidol, it is advised to monitor the ECG for arrhythmias for two to three hours, aligning with FDA recommendations.
In February 2020, the FDA approved amisulpride, a dopamine receptor antagonist, for the prevention and treatment of PONV. Amisulpride has proven to be more efficacious than placebo, particularly at a dose of 5 mg for prevention and 10 mg IV as a rescue treatment in patients who have not previously received an antidopaminergic agent for PONV prophylaxis. Side effects of amisulpride include mild elevation in serum prolactin levels, hypokalemia, chills, hypotension during injection, and injection site pain. It is contraindicated in patients receiving droperidol and those with congenital long QT syndrome, with ECG monitoring recommended for those with cardiac conduction disorders or on medications that prolong the QT interval.
Dosage recommendations for antidopaminergics:
- Droperidol: 0.625 to 1.25 mg IV.
- Haloperidol: 1 mg IV, or 1 mg oral, or 1 mg IM.
- Amisulpride: 5 mg IV injected over one to two minutes at the induction of anesthesia for prevention; 10 mg IV injected over one to two minutes as a rescue antiemetic post-surgery if an antidopaminergic agent has not been previously administered.
