Details
Presentation:
4 mg ODT
8 mg in 4 mL glass ampoule
Route:
Oral ODT – dissolve in mouth then swallow
IV – slow injection over at least 30 seconds (preferably over 3 – 5 minutes) reduces risk of adverse effects
IM – only if other routes of administration are unsuitable, due to large volume
Peak:
10 minutes (IV, IM)
30 minutes (Oral)
Duration:
Several hours
Mode of action
5-HT3 antagonist – exact mode of action is not fully understood. Release of serotonin (5-HT) is thought to trigger a vomiting reflex in both the peripheral (GIT) and central nervous system.
- Undifferentiated nausea and vomiting
- Prophylaxis where vomiting could be clinically detrimental (e.g. spinally immobilised, penetrating eye trauma)
- Apomorphine (see Significant Interactions)
- Pregnancy 1st trimester – consult with receiving hospital
- Congenital Long QT syndrome – ondansetron causes QT prolongation (dose-dependent effect) and increases the risk of Torsades de pointes in patients with a prolonged QT interval (QTC > 500 ms). Unlikely when administered at approved doses but avoid if patient has a history of congenital Long QT syndrome
- Severe hepatic disease (e.g. cirrhosis) – limit total daily dose to a maximum of 8 mg (all routes of administration)
- Ondansetron ODT may contain aspartame which should be avoided in patients with phenylketonuria. Ondansetron injection can be administered if appropriate
- CNS: Headache, dizziness
- CV: QT prolongation (rare)
- GI: Constipation
- Other: Visual disturbance, including transient loss of vision (rare, associated with rapid IV administration)
Significant interactions
- Apomorphine (injection used in the treatment of severe Parkinson’s disease) – reports of profound hypotension and loss of consciousness. Do not administer ondansetron to patients currently receiving apomorphine
Pregnancy
- 1st trimester – consult with receiving hospital
- 2nd and 3rd trimester – administer only if vomiting is very severe and benefits outweigh risk
- Consider IV fluid rehydration as per CPG A0701
- Considered safe
Notes
- Be aware of potential to confuse with Olanzapine ODT due to similarity in name and presentation
Infusion
- N/A