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Do Antiemetics Work? Droperidol, Ondansetron, Placebo

December 3, 2018

Correction: On Q22 of Saturday’s quiz, I selected the wrong “correct” answer. The risk of radiation-induced malignancy for children getting chest CT for trauma did not justify routine scanning given the low number of aortic injuries detected. Thanks to Dr. Strauss for pointing this out.

Written by Clay Smith

Spoon Feed
Neither droperidol 1.25mg IV nor ondansetron 8mg IV was better than placebo in achieving an 8mm reduction in nausea on visual analog scale (VAS). But ondansetron was slightly better than droperidol and placebo for overall mean nausea reduction and in patients experiencing the desired effect.

Why does this matter?
Prior studies have raised concern that antiemetics in the ED are not very effective, if at all. Aromatherapy may help, such as sniffing an alcohol pad.

Antiemetics aren’t all that…
This was a RCT comparing droperidol 1.25mg IV, ondansetron 8mg IV, and placebo 0.9% saline IV. At 30 minutes, there was no difference in the primary outcome of nausea by at least 8mm, as measured on VAS. Nausea improved 8mm on VAS in 75%, 80%, and 76% of patients, respectively. Ondansetron was more effective than placebo and droperidol for a secondary outcome of mean VAS score improvement, -34mm vs 24mm vs 29mm, respectively. The study was stopped early after the interim analysis showed futility for showing superiority of the active drugs for the primary outcome, enrolling 215 out of a planned 378 patients. More patients in the placebo group requested additional antinausea medication, 30% placebo; 15% droperidol; 23% ondansetron. Droperidol was more sedating than the other two. All patients received 0.9% saline at 250mL/hr x 4 hours. IV fluid alone may have been effective at relieving nausea.

How will I apply this in practice? Ondansetron wasn’t worthless. Another secondary outcome, experiencing the desired effect, was much better for ondansetron than placebo, NNT = 7. So, we can tell patients that ondansetron, in addition to IV fluid, is likely to further decrease nausea.

Another Spoonful
The Short Coat posted a great, quick review of this article.

Randomized placebo-controlled trial of droperidol and ondansetron for adult emergency department patients with nausea. Acad Emerg Med. 2018 Oct 28. doi: 10.1111/acem.13650. [Epub ahead of print]

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2 thoughts on “Do Antiemetics Work? Droperidol, Ondansetron, Placebo

  • Anti-emetics are supposed to prevent vomiting, and as far as I can tell from the paper no-one entered into the study vomited at any time, before, after, or during treatment. No wonder the study found no real difference between the drugs and placebo.

    The same reasoning applies to the other studies you quote above, where the outcomes are VAS numbers rather than episodes of vomiting.

    A VAS is easy to measure, many people in the ED feel nauseated, fewer vomit. Probably the VAS is a poor surrogate measure of the outcome of vomiting.

What are your thoughts?