The proper dose of Ondansetron is 4 mg every 8 hours as needed for nausea or vomiting, regardless of the route of administration. Each 8-hour dose can be repeated once after 15 minutes if nausea and vomiting are not improved. Do not give more than 8 mg in any 8-hour interval.
Ondansetron is available in a parenteral form (IV, IM, or IO) or as an orally disintegrating tablet (ODT) or regular pill form (PO). The advantage of the ODT preparation is the ability to use it without establishing IV or IO access or needing to draw up an IM dose. However, proper administration is needed as swallowing the ODT like an oral medication reduces its absorption, delays its onset of action, and is potentially diminished further by emesis if the casualty’s symptoms persist or progress. Oral ondansetron is NOT an acceptable alternative to the ODT formulation.
Ondansetron is used for the prevention and management of nausea and vomiting associated with pain management medications.
Contraindications include hypersensitivity. Use cautiously in patients with hepatic failure; considered relatively safe in pregnancy, if clinically indicated.
Nausea and vomiting are common side effects of opiates, particularly in trauma victims. When the TCCC Guidelines were initially developed, the anti-emetic of choice was promethazine. Although a very effective medication, sedation, respiratory depression, impairment of psychomotor and cognitive function, and hypotension that were often seen as side-effects were problematic. Additionally, an FDA black box warning for injection site tissue necrosis was a concern.