Ondansetron (Burns/Procedural Antiemetic)

Fetched UK SPC is Ondansetron 2 mg/ml Solution for Injection (https://www.medicines.org.uk/emc/product/6469/smpc). CHEMOTHERAPY AND RADIOTHERAPY INDUCED NAUSEA AND VOMITING (a different indication in the same SPC, given for reference — do not substitute for the PONV dose above): for emetogenic chemotherapy or radiotherapy, 8 mg as a slow intravenous injection (not less than 30 seconds) or as an infusion over 15 minutes immediately before treatment, followed by treatment with dosage forms other than intravenous to protect against delayed or prolonged emesis after the first 24 hours. For highly emetogenic chemotherapy (e.g. high-dose cisplatin), three equally effective intravenous schedules over the first 24 hours are described: (i) a single 8 mg dose by slow intravenous injection immediately before chemotherapy; (ii) 8 mg by slow intravenous injection or short 15-minute infusion immediately before chemotherapy, followed by two further intravenous doses of 8 mg four hours apart, or by a constant infusion of 1 mg/hour for up to 24 hours; (iii) a maximum initial intravenous dose of 16 mg diluted in 50-100 ml sodium chloride 9 mg/ml (0.9% w/v) or other compatible fluid and infused over not less than 15 minutes immediately before chemotherapy, optionally followed by two additional 8 mg intravenous doses four hours apart. Efficacy in highly emetogenic chemotherapy may be enhanced by a single intravenous dose of dexamethasone sodium phosphate 20 mg before chemotherapy. ELDERLY: patients 65 to 74 years may follow the adult schedule, with all intravenous doses diluted in 50-100 ml of saline or other compatible fluid and infused over 15 minutes; in patients 75 years or older the initial intravenous dose should not exceed 8 mg, and may be followed by two further 8 mg intravenous doses infused over 15 minutes and given no less than four hours apart. HEPATIC IMPAIRMENT: in moderate or severe impairment, clearance is significantly reduced and half-life prolonged — a total daily dose of 8 mg should not be exceeded. Poor sparteine/debrisoquine metabolisers: no alteration of daily dosage or frequency required. SAFETY: ondansetron prolongs the QT interval in a dose-dependent manner and post-marketing cases of torsade de pointes have been reported — avoid in congenital long QT syndrome, use with caution where QTc prolongation may develop, and correct hypokalaemia and hypomagnesaemia before administration. Cases of myocardial ischaemia have been reported, in some patients immediately after intravenous administration. In patients having adenotonsillar surgery, prevention of nausea and vomiting may mask occult bleeding — follow such patients carefully.

PONV in children aged 1 month and over and adolescents, per the fetched UK SPC (Ondansetron 2 mg/ml Solution for Injection). There are no data on the use of ondansetron in the TREATMENT of PONV in children below 2 years of age. Separate CINV dosing for children aged 6 months and over and adolescents (a different indication): by bodyweight, a single intravenous dose of 0.15 mg/kg immediately before chemotherapy with up to two further intravenous doses at 4-hourly intervals; or by body surface area, a single intravenous dose of 5 mg/m2 immediately before chemotherapy. In both CINV routes the intravenous dose must not exceed 8 mg and the total daily dose must not exceed the adult dose of 32 mg; weight-based dosing results in higher total daily doses than BSA-based dosing. For CINV the injection should be diluted in 5% glucose or 0.9% sodium chloride or other compatible infusion fluid and infused over not less than 15 minutes. Paediatric patients receiving ondansetron with hepatotoxic chemotherapeutic agents should be monitored closely for impaired hepatic function. Verify all paediatric dosing against a children's formulary.