Table 24

Ondansetron orodispersible or rectal

Ondansetron orodispersible or rectal
What is it?Anti-emetic
Mechanism of actionAnti-serotonin 5HT3
Starting doseBuccal 4 mg prn, max 16 mg in 24 hours; rectal 16 mg suppositories
Time to onset of effectUncertain (<30 min with oral route)17
FormulationOrodispersible film 4 mg
OR orodispersible tablets 4 mg 6–8 hourly PRN max 16 mg/24 hours
16 mg suppositories only dose available
IndicationNausea 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
CautionMay reduce efficacy of tramadol and paracetamol17
LicencingLicensed formulation for an ‘off label’ indication in palliative care
BenefitsLicenced orodispersible and rectal alternative anti-emetic
RisksConstipation, 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