ondansetron

Ondansetron blocks the actions of chemicals in the body that can trigger nausea and vomiting.

Ondansetron is used to prevent nausea and vomiting that may be caused by surgery or by medicine to treat cancer (chemotherapy or radiation).

Ondansetron is not for preventing nausea or vomiting that is caused by factors other than cancer treatment or surgery.

Important information

You should not use ondansetron if you are also using apomorphine (Apokyn).

You should not use ondansetron if you are allergic to ondansetron or to similar medicines such as dolasetron (Anzemet), granisetron (Kytril), or palonosetron (Aloxi). Do not take ondansetron if you are also using apomorphine (Apokyn)

Before taking ondansetron, tell your doctor if you have liver disease, or a personal or family history of Long QT syndrome.

Ondansetron orally disintegrating tablets may contain phenylalanine. Tell your doctor if you have phenylketonuria (PKU).

Serious side effects of ondansetron include blurred vision or temporary vision loss (lasting from only a few minutes to several hours), slow heart rate, trouble breathing, anxiety, agitation, shivering, feeling like you might pass out, and urinating less than usual or not at all. Stop taking ondansetron and call your doctor at once if you have any of these side effects. Ondansetron may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert.

Before taking this medicine

You should not use ondansetron if you are also using apomorphine (Apokyn).

To make sure ondansetron is safe for you, tell your doctor if you have:

• liver disease; or

• if you are allergic to medicines similar ondansetron (dolasetron, granisetron, palonosetron).

FDA pregnancy category B. Ondansetron is not expected to harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant during treatment.

See also: Pregnancy and breastfeeding warnings (in more detail)

It is not known whether ondansetron passes into breast milk or if it could harm a nursing baby. Tell your doctor if you are breast-feeding a baby.

Ondansetron should not be given to a child younger than 4 years old.

Ondansetron orally disintegrating tablets may contain phenylalanine. Tell your doctor if you have phenylketonuria (PKU).

How should I take ondansetron?

Take ondansetron exactly as prescribed by your doctor. Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended.

Ondansetron can be taken with or without food.

The first dose is usually taken before the start of your surgery, chemotherapy, or radiation treatment. Follow your doctor"s dosing instructions very carefully.

Take the ondansetron regular tablet with a full glass of water.

To take the orally disintegrating tablet (Zofran ODT):

• Keep the tablet in its blister pack until you are ready to take it. Open the package and peel back the foil. Do not push a tablet through the foil or you may damage the tablet.

• Use dry hands to remove the tablet and place it in your mouth.

• Do not swallow the tablet whole. Allow it to dissolve in your mouth without chewing.

• Swallow several times as the tablet dissolves.

To use ondansetron oral soluble film (strip) (Zuplenz):

• Keep the strip in the foil pouch until you are ready to use the medicine.

• Using dry hands, remove the strip and place it on your tongue. It will begin to dissolve right away.

• Do not swallow the strip whole. Allow it to dissolve in your mouth without chewing.

• Swallow several times after the strip dissolves. If desired, you may drink liquid to help swallow the dissolved strip.

• Wash your hands after using Zuplenz.

Measure liquid medicine with the dosing syringe provided, or with a special dose-measuring spoon or medicine cup. If you do not have a dose-measuring device, ask your pharmacist for one.

Store at room temperature away from moisture, heat, and light.

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include sudden loss of vision, severe constipation, feeling light-headed, or fainting.

What should I avoid while taking ondansetron?

Ondansetron may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert.

Ondansetron side effects

Get emergency medical help if you have any of these signs of an allergic reaction to ondansetron: rash, hives; fever, chills, difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

• fast or pounding heartbeats;

• jaundice (yellowing of the skin or eyes);

• blurred vision or temporary vision loss (lasting from only a few minutes to several hours); or

• high levels of serotonin in the body - agitation, hallucinations, fever, fast heart rate, overactive reflexes, nausea, vomiting, diarrhea, loss of coordination, fainting.

Common ondansetron side effects may include:

• diarrhea or constipation;

• headache;

• drowsiness; or

• tired feeling.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

See also: Side effects (in more detail)

Ondansetron dosing information

Usual Adult Dose of Ondansetron for Nausea/Vomiting - Chemotherapy Induced:

Recommended dose: Three 0.15 mg/kg doses (up to a maximum of 16 mg per dose). The first dose is infused over 15 minutes beginning 30 minutes before the start of emetogenic chemotherapy. Subsequent doses (0.15 mg/kg up to a maximum of 16 mg per dose) are administered 4 and 8 hours after the first dose.

Alternative therapies:
Oral soluble film dosage form:
Highly emetogenic cancer chemotherapy: 24 mg given successively as three 8 mg films administered 30 minutes before the start of single-day highly emetogenic chemotherapy, including cisplatin greater than or equal to 50 mg/m2.
Moderately emetogenic cancer chemotherapy: One 8 mg soluble film given 2 times a day. The first dose should be administered 30 minutes before the start of emetogenic chemotherapy, with a subsequent dose 8 hours after the first dose.

Usual Adult Dose of Ondansetron for Nausea/Vomiting:

Recommended dose: Three 0.15 mg/kg doses (up to a maximum of 16 mg per dose). The first dose is infused over 15 minutes beginning 30 minutes before the start of emetogenic chemotherapy. Subsequent doses (0.15 mg/kg up to a maximum of 16 mg per dose) are administered 4 and 8 hours after the first dose.

Alternative therapies:
Oral soluble film dosage form:
Highly emetogenic cancer chemotherapy: 24 mg given successively as three 8 mg films administered 30 minutes before the start of single-day highly emetogenic chemotherapy, including cisplatin greater than or equal to 50 mg/m2.
Moderately emetogenic cancer chemotherapy: One 8 mg soluble film given 2 times a day. The first dose should be administered 30 minutes before the start of emetogenic chemotherapy, with a subsequent dose 8 hours after the first dose.

Usual Adult Dose for Nausea/Vomiting - Postoperative:

4 mg IV (undiluted) over 2 to 5 minutes, or IM, immediately before induction of anesthesia or postoperatively if nausea or vomiting occurs within 2 hours after surgery. Alternatively, 4 mg (undiluted) may be administered intramuscularly as a single injection for adults. While recommended as a fixed dose for patients weighing more than 40 kg, few patients above 80 kg have been studied. Patients who do not achieve adequate control of postoperative nausea and vomiting following a single, prophylactic, preinduction, intravenous dose of ondansetron 4 mg, administration of a second intravenous dose of 4 mg ondansetron postoperatively does not provide additional control of nausea and vomiting.

16 mg orally 1 hour before induction of anesthesia.

Oral soluble film dosage form: 16 mg given as successively as two 8 mg oral soluble films 1 hour before induction of anesthesia.

Usual Adult Dose for Nausea/Vomiting - Radiation Induced:

8 mg orally every 8 hours, give the first dose 1 to 2 hours prior to radiotherapy.

Oral soluble film dosage form:
One 8 mg soluble film given 3 times a day.
For total body irradiation: One 8 mg soluble film given 1 to 2 hours before each fraction of radiotherapy administered each day.
For single high-dose fraction radiotherapy to the abdomen: One 8 mg oral soluble film given 1 to 2 hours before radiotherapy, with subsequent doses every 8 hours after the first dose for 1 to 2 days after completion of radiotherapy.
For daily fractionated radiotherapy to the abdomen: One 8 mg oral soluble film given 1 to 2 hours before radiotherapy, with subsequent doses every 8 hours after the first dose for each day radiotherapy is given.

Usual Adult Dose of Ondansetron for Pruritus:

Study (n=150) - Induced by Intrathecal Fentanyl
8 mg IV before spinal anesthesia.

Usual Adult Dose for Alcohol Dependence:

Study (n=321) - Early onset alcoholism
4 mcg/kg two times daily.

Usual Adult Dose of Ondansetron for Postanesthetic Shivering:

Study (n=82)
8 mg IV, 3 to 5 minutes before the induction of anesthesia.

Usual Pediatric Dose for Nausea/Vomiting - Postoperative:

1 month to 12 years:
40 kg or less: 0.1 mg/kg single dose IV, administered over 2 to 5 minutes, immediately prior to or following anesthesia induction, or postoperatively if nausea and/or vomiting present shortly after surgery.

40 kg or more: 4 mg single dose IV, administered over 2 to 5 minutes, immediately prior to or following anesthesia induction, or postoperatively if nausea and/or vomiting present shortly after surgery.

Usual Pediatric Dose of Ondansetron for Nausea/Vomiting - Chemotherapy Induced:

Child 6 months to 18 years: 0.15 mg/kg (maximum of 16 mg per dose) as an IV infusion (over 15 minutes) administered 30 minutes before the start of emetogenic therapy, then at 4 and 8 hours after the first dose, respectively.

4 to 11 years: 4 mg orally given 30 minutes before the start of emetogenic therapy, then 4 mg orally 4 and 8 hours after the first dose. Thereafter, 4 mg orally every 8 hours for 1 to 2 days after emetogenic therapy is complete.

11 years or older:: 8 mg orally 3 times daily, or 24 mg orally once daily.

Oral soluble film dosage form: Use of ondansetron oral soluble films is not indicated for treatment of nausea and vomiting associated with highly emetogenic cancer chemotherapy in pediatric patients.
For prevention of nausea and vomiting associated with moderately emetogenic cancer chemotherapy: For pediatric patients 12 years of age and older, the dosage is the same as for adults. For pediatric patients 4 through 11 years of age, the dosage is one 4 mg oral soluble film given 3 times a day. The first dose should be administered 30 minutes before the start of emetogenic chemotherapy, with subsequent doses 4 and 8 hours after the first dose. One 4 mg oral soluble film should be administered 3 times a day (every 8 hours) for 1 to 2 days after completion of chemotherapy.

Usual Pediatric Dose for Gastroenteritis:

Study (n=145) - Control of emesis during the ED phase of oral rehydration:
6 months to 12 months: 1.6 mg orally every 8 hours
1 year to 3 years: 3.2 mg orally every 8 hours
4 years or older: 4 mg orally every 8 hours

Dosage was administered 15 minutes before the start of oral rehydration.

What other drugs will affect ondansetron?

There are many other medicines that can increase your risk of heart rhythm problems if you use them together with ondansetron.

Tell your doctor about all medicines you use, and those you start or stop using during your treatment with ondansetron, especially:

• anagrelide;

• droperidol;

• methadone;

• an antibiotic - azithromycin, clarithromycin, erythromycin, levofloxacin, moxifloxacin, pentamidine;

• cancer medicine - arsenic trioxide, vandetanib;

• an antidepressant - citalopram, escitalopram;

• anti-malaria medication - chloroquine, halofantrine;

• heart rhythm medicine - amiodarone, disopyramide, dofetilide, dronedarone, flecainide, ibutilide, quinidine, sotalol; or

• medicine to treat a psychiatric disorder - chlorpromazine, haloperidol, pimozide, thioridazine.

This list is not complete. Other drugs may interact with ondansetron, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.