Type of medicine 5HT3 antagonist
Used for Prevention of sickness after chemotherapy, radiotherapy or surgery
Also called Zofran
Ondemet
Available as Tablets, melt tablets
Syrup
Suppositories
Injection

Chemotherapy, radiotherapy and surgery cause the release of a chemical serotonin (5HT) in the stomach. This serotonin acts on receptors called 5HT3 and causes sickness. Zofran works by blocking these 5HT3 receptors and therefore stopping you from feeling or being sick.

Why is this drug prescribed?

Zofran tablets, syrup and injection all contain the active ingredient ondansetron hydrochloride dihydrate, which is a type of drug called a 5HT3 antagonist. Ondansetron is also available without a brand name, ie as the generic drug. Ondansetron is used to prevent and treat nausea and vomiting that can be caused by chemotherapy or radiotherapy treatment for cancer, or by surgery. Vomiting is controlled by an area of the brain called the vomiting centre. The vomiting centre is responsible for causing feelings of sickness and for the vomiting reflex. It is activated when it receives nerve messages from another area of the brain called the chemoreceptor trigger zone and when it receives nerve messages from the gut. Chemotherapy, radiotherapy and surgery can cause a substance called serotonin to be released in the gut. This 5HT acts on the 5HT3 receptors that are found in the gut and causes nerve messages to be sent to the vomiting centre. 5HT released by chemotherapy, radiotherapy and surgery also activates the 5HT3 receptors that are found in the CTZ in the brain, causing further messages to be sent to the vomiting centre. Ondansetron works by blocking the 5HT3 receptors that are found in the brain and gut. This prevents the nausea messages being sent from these areas to the vomiting centre. Ondansetron therefore prevents nausea, retching and vomiting that can otherwise occur following surgery or due to cancer treatments. Ondansetron can be given by mouth, by injection into a muscle or vein, by drip into a vein, or by suppository.

Treatments

* Preventing and treating nausea and vomiting caused by chemotherapy or radiotherapy for cancer * Preventing and treating nausea and vomiting following surgery.

What side effects can this drug cause?

* Headache * Constipation * Flushing * Hiccups * Allergy to active ingredient * Involuntary movements * Alteration in results of liver function tests * Low blood pressure * Chest pain * Slow heart rate * Abnormal heart beats * Seizures