Ondansetron

(on-dan-sih-tron)

Trade/other name(s): Zofran

Why would this drug be used?

Ondansetron is used to prevent nausea and vomiting from chemotherapy and radiation. It is also used to prevent vomiting after surgery.

How does this drug work?

Ondansetron is part of a general class of drugs called serotonin antagonists. It blocks the serotonin pathway to the vomiting center in the brain so the brain no longer receives a message to vomit.

Before taking this medicine

Tell your doctor…

• If you are allergic to anything, including medicines, dyes, additives, or foods.
• If you have or have had abnormal heart rhythm, including long Q-T interval, heart block, or heart failure. In some people, ondansetron can make these problems worse.
• If you have liver disease (including hepatitis), your dose of ondansetron may need to be lower.
• If you are pregnant, trying to get pregnant, or if there is any chance of pregnancy. Even though tests did not show any damage in pregnant animals, ondansetron has not been tested in pregnant women.
• If you are breast-feeding. It is not known whether this drug passes into breast milk. If it does, it could harm the baby.

About any other prescription or over-the-counter medicines you are taking, including vitamins and herbs. In fact, keeping a written list of each of these medicines (including the doses of each and when you take them) with you in case of emergency may help prevent complications if you get sick.

Interactions with other drugs

Drugs that affect the heart rhythm or the electrical impulses of the heart can cause abnormal heart rhythms if taken with this drug.

Do not use this drug if you take apomorphine (Apokyn) for Parkinson's disease.

Check with your doctor, nurse, or pharmacist about other medicines, vitamins, herbs, and supplements, and whether alcohol can cause problems with this medicine.

Interactions with foods

No serious interactions with food are known at this time. Check with your doctor, nurse, or pharmacist about whether foods may be a problem.

Tell all the doctors, dentists, nurses, and pharmacists you visit that you are taking this drug.

How is this drug taken or given?

Ondansetron is taken as a pill, a tablet that dissolves on the tongue, as a liquid, or as an injection in a vein over a period of 30 minutes. Take the pill, tablet, or liquid 30 minutes to 1 hour before the chemotherapy or radiation is given, as instructed by your doctor or nurse. If taking the liquid, you will need to shake it before pouring the dose. The dose depends on which treatment you are receiving and whether you have had problems with nausea and vomiting in the past. Take this drug exactly as directed by your doctor. If you do not understand the instructions, ask your doctor or nurse to explain them to you.

Store the medicine in a tightly closed container away from light, high temperatures, and moisture, and out of the reach of children and pets.

Precautions

Call your doctor or nurse right away if you notice itching, welts on your skin (hives), shortness of breath, dizziness, swelling of the face or mouth, or any trouble breathing or swallowing. These can be symptoms of an allergic reaction, which must be treated quickly.

Your doctor may watch your EKG while you are taking this drug if you have low potassium, low magnesium, slow heartbeat, congestive heart failure, or if you are taking other drugs that can affect heart rhythm.

Possible side effects

You will probably not have most of the following side effects, but if you have any talk to your doctor or nurse. They can help you understand the side effects and cope with them.

Common

• diarrhea
• constipation
• headache

Rare

• abnormal liver function test results that go away after treatment
• rash, hives
• abnormal heart rhythm*
• serious allergic reaction*

*See "Precautions" section for more detailed information

There are some other side effects not listed above that can also occur in some patients. Tell your doctor or nurse if you develop these or any other problems.

FDA approval

Yes – first approved in 1992.

Disclaimer: This information does not cover all possible uses, actions, precautions, side effects, or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for talking with your doctor, who is familiar with your medical needs.