Ondansetron: Price, Dosage & Where to Buy

Ondansetron is a medicine used to prevent nausea and vomiting. It belongs to the 5-HT3 receptor antagonist class and is most commonly prescribed to prevent sickness linked with cancer chemotherapy, radiotherapy or an operation.

It requires a prescription in the United Kingdom. Generic ondansetron has been available since 2006-12-26.

Ondansetron is a 5-HT3 receptor antagonist. Serotonin is one of the chemical messengers that can activate the vomiting reflex, particularly during cancer treatment, radiotherapy or after an operation. Ondansetron blocks 5-HT3 receptors in areas involved in this reflex, including the gut and the nervous system.

This reduces the signals that can trigger nausea and vomiting. It does not stimulate movement of the stomach or intestines, so it should not replace treatment for a bowel blockage or the use of nasogastric suction when that is needed. The medicine helps prevent sickness but does not treat the underlying cancer, radiation exposure or effects of surgery.

Ondansetron is used to prevent nausea and vomiting caused by highly or moderately emetogenic cancer chemotherapy. It is also used when radiotherapy may cause sickness, including total body irradiation, a single high-dose treatment to the abdomen, or daily treatments to the abdomen. Another use is preventing nausea and vomiting after an operation.

The medicine is intended to prevent sickness linked with these treatments rather than treat every possible cause of nausea. Its use in children is established for preventing nausea and vomiting associated with moderately emetogenic cancer chemotherapy from 4 years of age and older.

The label lists oral solution at 4 mg/5 mL, oral tablets at 4 mg and 8 mg, film-coated tablets at 4 mg, 8 mg, 16 mg and 24 mg, and orally disintegrating tablets at 4 mg, 8 mg, 16 mg and 24 mg. Injectable forms are listed at 2 mg/mL, including 4 mg/2 mL solution. The usual starting dose is a single 24 mg dose before highly emetogenic chemotherapy.

The label lists 8 mg before moderately emetogenic chemotherapy, followed by another 8 mg dose and then 8 mg twice a day for 1 to 2 days. The label lists 8 mg before radiotherapy, with further doses depending on the radiotherapy schedule.

The label lists 16 mg before induction of anaesthesia for postoperative prevention. The label lists a total daily limit of 8 mg for severe hepatic impairment.

Store at 20° to 25°C, with excursions permitted to 15° to 30°C. Keep orally disintegrating tablets in a tight, light-resistant container as defined in the label. Protect the tablets from moisture and follow the product packaging instructions to maintain quality.

A missed dose means a scheduled dose was not administered at the planned time. The correct action depends on whether ondansetron is being used around chemotherapy, radiotherapy or an operation, because the label links doses to these treatments.

A doctor, oncology team, hospital team or pharmacist should advise what to do. A double dose should not be used to make up for a missed dose unless a prescriber specifically directs this.

Available data do not reliably show whether ondansetron is associated with adverse fetal outcomes. Published studies have reported inconsistent findings and have important limitations. Animal studies did not show evidence of harm to the fetus at the doses studied.

It is not known whether ondansetron is present in human milk, and there are no data on effects on a breastfed infant or milk production. Pregnancy or breastfeeding should be discussed with a doctor or pharmacist.