Myth Bust – Ondansetron and IV Opiate-Induced Nausea

November 22, 2017

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Prophylactic ondansetron given with IV opiates did not decrease the rate of nausea or vomiting.

Why does this matter?
Prior RCT data on this topic found a paradoxical trend toward metoclopromide making nausea worse when given with IV opiates.  A subsequent study found either 8 or 16mg of ondansetron was more effective than placebo at relieving nausea associated with IV opiates but did not study prophylaxis.  This was a prospective look at current practice from one institution.

OK, that’s morphine with a side of hydromorphone. Would you like ondansetron with that?
This was a prospective study of 64 patients receiving IV opiates only and 69 patients receiving an opiate plus ondansetron.  Co-administration of ondansetron was left to the discretion of the treating physician.  All patients had nausea measured using a numeric rating scale at baseline, 5 minutes after opioid administration, and 30 minutes after opioid administration.  Overall incidence of nausea was the same in each group, with a trend toward worsening symptoms in the ondansetron group, 20% vs 14% (not statistically significant).  Prophylactic administration of ondansetron did not reduce the need for rescue medicine.  The study was limited by its small size and non-randomized design.  Routine prophylactic treatment with an antiemetic plus opiate appeared to be ineffective and raised concerns about the benefit vs potential increase in cost and side effects.

Source
Use of Prophylactic Ondansetron with Intravenous Opioids in Emergency Department Patients: A Prospective Observational Pilot Study.  J Emerg Med. 2017 Oct 5. pii: S0736-4679(17)30616-9. doi: 10.1016/j.jemermed.2017.06.040. [Epub ahead of print]

Peer reviewed by Thomas Davis, MD.