ONDANSETRON-WGR

What it is

Ondansetron-WGR contains ondansetron hydrochloride dihydrate. It is an antinauseant/antiemetic and a potent, highly selective 5HT3-receptor antagonist.

Approved indications

— Prevention and treatment of nausea and vomiting induced by cytotoxic therapy and radiotherapy. — Prevention and treatment of post-operative nausea and vomiting.

Dosing overview

The route of administration and dose of ondansetron should be flexible in the range of 8 to 32 mg a day and selected according to indication. The lowest effective dose should be used. For chemotherapy and radiotherapy-induced nausea and vomiting, a single dose of 8 mg should be administered as a slow intravenous injection in not less than 30 seconds, immediately before treatment. Higher doses may be required in some patients, particularly those on high dose cisplatin, with additional intravenous doses given up to a maximum of 32 mg in 24 hours. Intravenous doses of more than 8 mg should be given by slow intravenous infusion over at least 15 minutes. For post-operative nausea and vomiting in adults, ondansetron may be administered as a single dose of 4 mg, given by intramuscular or slow intravenous injection at induction of anaesthesia. For treatment of established post-operative nausea and vomiting, a single dose of 4 mg given by intramuscular or slow intravenous injection is recommended in most patients, with the dose potentially increased to 8 mg if necessary.

Key safety warnings

Ondansetron prolongs the QT interval in a dose-dependent manner, and post-marketing cases of Torsades de Pointes have been reported; it should be avoided in patients with congenital long QT syndrome. It should be administered with caution to patients who have or may develop prolongation of QTc, including patients with electrolyte abnormalities, congestive heart failure, bradyarrhythmias or patients taking other medicinal products that lead to QT prolongation, and hypokalemia and hypomagnesemia should be corrected prior to administration. Serotonin syndrome has been described following the concomitant use of ondansetron and other serotonergic drugs, and if concomitant treatment is clinically warranted, appropriate observation of the patient is advised. Cases of myocardial ischaemia have been reported in patients treated with ondansetron, with symptoms sometimes appearing immediately after administration particularly following intravenous administration, and patients should be alerted to the signs and symptoms of myocardial ischaemia. As ondansetron is known to increase large bowel transit time, patients with signs of subacute intestinal obstruction should be monitored following administration.

Contraindications

Hypersensitivity to ondansetron or to any component of the preparation is a contraindication. Based on reports of profound hypotension and loss of consciousness when ondansetron was administered with apomorphine hydrochloride, concomitant use with apomorphine is contraindicated.

Regulatory history

Ondansetron-WGR 4 mg and 8 mg tablet formulations were first listed on the ARTG on 17 January 2024.