Ondansetron orodispersible or rectal
| Ondansetron orodispersible or rectal | |
| What is it? | Anti-emetic |
| Mechanism of action | Anti-serotonin 5HT3 |
| Starting dose | Buccal 4 mg prn, max 16 mg in 24 hours; rectal 16 mg suppositories |
| Time to onset of effect | Uncertain (<30 min with oral route)17 |
| Formulation | Orodispersible film 4 mg OR orodispersible tablets 4 mg 6–8 hourly PRN max 16 mg/24 hours OR 16 mg suppositories only dose available |
| Indication | Nausea and vomiting |
| Common adverse effects | ‘Constipation; feeling hot; headache; sensation abnormal’16 |
| Contraindications | ‘Congenital long QT syndrome’16 Serious drug interaction with metoclopramide due to combined QT prolongation effect17 |
| Caution | May reduce efficacy of tramadol and paracetamol17 |
| Licencing | Licensed formulation for an ‘off label’ indication in palliative care |
| Benefits | Licenced orodispersible and rectal alternative anti-emetic |
| Risks | Constipation, more costly than other alternatives such as olanzapine |
| Cost | £28.50 for 10×4 mg or £57 for 10×8 mg orodispersible films; £43.38 for 10×4 mg or £85.43 for 10×8 mg orodispersible tablets; £14.39 for 1×16 mg suppository |