Ondansetron is a serotonin 5-HT3 receptor antagonist that blocks serotonin action in the body to help prevent nausea and vomiting. This drug is commonly prescribed to those undergoing medical treatments that are known to cause severe nausea such as cancer treatments or major surgery that will require anesthesia. Patients will usually be given this medication under a doctor's direct supervision, though you may be given a final dose at home after your treatment is complete.
Indications and Usage
Ondansetron is sold under the brand names Zolfran, Zolfran ODT and Zuplenz. These medications are available as a tablet, rapidly disintegrating tablet or film, and an oral solution, all of which are to be taken orally. It is prescribed to those undergoing chemotherapy, radiation therapy and surgery to help prevent nausea. This drug may also be injected into your body through your IV. If you are taking the disintegrating tablet, make sure you read the directions on the package carefully to make sure you do not accidently begin the disintegrating process before you can insert the drug into your mouth.
Ondansetron Dosage
Dosing of ondansetron as an anti-nausea agent during cancer treatment will vary based on the type of medication that you are using. Traditional oral tablets will be prescribed in 8 mg doses. You will take one dose 30 minutes before you start your treatment, then a dose eight hours later, followed by a dose every 12 hours. Those using ondansetron strictly for anti-nausea purposes may start with 24 mg before their treatment begins, followed by 8 mg every eight hours. Those using the soluble film will follow an identical dosing schedule. Adults receiving ondansetron for radiation therapy will receive 8 mg three times a day. Those using this medication to avoid nausea after surgery will be given 16 mg 1 hour before their anesthesia.
Children ages 4-11 will be given 4 mg of ondansetron 30 minutes before their cancer treatment begins. This will be followed by 4 mg doses every 8 hours. The use of the soluble film version of ondansetron commonly prescribed for radiation therapy or surgery patients should be determined by your doctor. The use of ondansetron in children under the age of 4 is not recommended.
Table 1: Ondansetron Dosage
|
Indications |
Usual Dosage |
Special Dosage |
|---|---|---|
|
Cancer |
Oral - 8 mg 30 minutes before starting treatment, followed by 8 mg in 8 hours, then 8 mg every 12 hours. Anti-nausea - 24 mg 30 minutes before treatment, then 8 mg every 8 hours. Film - 8 mg 30 minutes before treatment, then 8 mg every 8 hours. |
Children 4-11 take 4 mg 30 minutes before treatment, 4 mg 8 hours later, then 4 mg every 8 hours. Anti-nausea use should be determined by your doctor. Film - Children ages 4-11 may take 4 mg 30 minutes before starting treatment, then 4 mg every 8 hours. |
|
Radiation Treatment |
One 8 mg soluble film, 3 times a day. |
A child's use of the soluble film to be determined by your doctor. |
|
Surgery |
16 mg one hour before anesthesia. |
Children's dosing should be determined by your doctor. |
Ondansetron Side Effects
The most common side effect of ondansetron is headaches which occur in up to 27 percent of users. Other common side effects include tiredness or fatigue which occurs in 13 percent of users, a general ill feeling in 13 percent, constipation in 9 percent, low oxygen levels in up to 9 percent of surgery patients, fever in 8 percent, diarrhea in 7 percent, gynecological disorders in up to 7 percent of female users, anxiety or agitation in 6 percent, difficulties emptying the bladder in 5 percent, itching in 5 percent and dizziness in up to 5 percent of users. These side effects are not usually serious, but you may need to inform your doctor regarding any conditions you experience while using ondansetron to help monitor your condition as a whole.
Rare side effects of ondansetron include shakiness, unusually stiff muscles, increased liver enzymes, chest pain, and changes in heart rhythm, flushing, hiccups, and spasms of the eye, the eye becoming fixed in a specific position or temporary blindness. Let your doctor know if these side effects occur so you can determine a proper course of treatment.
If you begin to suffer from chest pain, unexplained rash, itching, hives, unexplained swelling, wheezing, difficulty breathing, difficulty swallowing, unsteady or shaky movements or tremors, contact your doctor right away. These are signs that you may be having a negative reaction to your medication. If at any point you feel as though these side effects have become severe or you feel as though you might lose consciousness, contact your emergency medical services immediately.
If you suddenly experience sudden loss of vision for a short time, dizziness, lightheadedness, fainting, constipation or irregular heartbeat, you may be suffering from an overdose of ondansetron. Contact emergency medical services and poison control to get help as quickly as possible.
Table 2: Ondansetron Side Effects
|
Types of Side Effects |
Symptoms |
|---|---|
|
Common Side Effects |
Headache, tiredness, general ill feeling, constipation, low oxygen levels (surgery patients), fever, diarrhea, gynecological disorders, anxiety, difficulty emptying the bladder, itching and dizziness. |
|
Rare Side Effects |
Shakiness, unusually stiff muscles, increased liver enzymes, chest pain, changes in heart rhythm, flushing, hiccups, spasms of the eye, the eye becoming fixed in a specific position and temporary blindness. |
|
Serious Side Effects |
Chest pain, unexplained rash, itching, hives, unexplained swelling, wheezing, difficulty breathing, difficulty swallowing, unsteady or shaky movements and tremors. |
|
Overdose |
Sudden loss of vision for a short time, dizziness, lightheadedness, fainting, constipation or irregular heartbeat. |
Interactions
Medications that are known to interfere with the oral version of ondansetron include arsenic trioxide, tacrolimus, tramadol, antibiotics, antidepressants, anti-malaria medication, heart rhythm medication, other medications used to decrease vomiting, anti-psychotic medications, migraine medications, seizure medications, and narcotic based medications. Your doctor should be aware of any medications that are in your system, but be sure to mention any medications that are not in your records before starting on any treatments that might include ondansetron.
Medications which are known to interfere with the injected form of ondanestron include arsenic trioxide, tacrolimus, tramadol, antibiotics, antidepressants, anti-malaria medications, hearty rhythm medications, medications used to prevent nausea or vomiting, anti-psychotic medications, migraine medications, and narcotic based medications. Many of these negative reactions are identical to those for the oral type of medication, so you may not need to report your prescription list a second time if you are being switched from one version to the other. Your doctor will go over all of this information with you if necessary.
Ondansetron will impair your thinking and reaction time and may cause you to have blurred vision. Be careful when doing anything that will require your full attention, and do not drive until you know how this medication will affect you.