Ondansetron

• There is no evidence demonstrating a benefit of timing ondansetron administration in children with respect to the time of surgery
• If required in patients under six months a dose of 0.1 mg/kg should be used
• Ondansetron and other 5HT₃ antagonists should be avoided in children where prolonged QT interval is known or suspected

Dexamethasone

• Effective anti-emetic in children on its own and in combination with 5HT₃ antagonists.
• Multiple small studies have investigated the effect of the dose for PONV - higher doses were associated with no further reduction in PONV and had a higher rate of side effects
• IV dexamethasone may cause perineal warmth and should be injected slowly in the conscious child
• Dexamethasone should not be used in patients at risk of tumour lysis syndrome

Droperidol

• Used as an antipsychotic and anti-emetic drug for several decades
• Has sedative effects, prolongs the QT interval and can cause extra-pyramidal symptoms
• Effective anti-emetic and relieves nausea singly and in combination. It can be used both as prophylaxis and as rescue therapy.
• Should be diluted in 0.9% NaCl and given as a slow IV bolus
• The use of droperidol is generally confined to rescue therapy or as a second line agent, rather than prophylaxis because of the concerns around sedation and extra-pyramidal side effects
• Contraindicated in patients with known long QT syndrome.