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Zofran (ondansetron) is a prescription antiemetic medication taken orally or by injection to treat nausea and/or vomiting resulting from surgery, cancer chemotherapy, or cancer radiation therapy. Zuplenz is another formulation of ondansetron, manufactured by Galena Biopharma Inc.
Zofran and Pregnancy
Zofran and Zuplenz have also been used “off-label” to prevent or treat symptoms of nausea and vomiting associated with pregnancy, commonly called morning sickness, although the U.S. Food and Drug Administration (FDA) has not approved these drugs for this indication.
Zofran and Zuplenz are antiemetics known as 5-HT3 receptor antagonists that exhibit a strong affinity for only certain 5-HT3 receptors, such as those of the central nervous system’s afferent branches of the vagus nerve. These 5-HT3 receptors attract serotonin produced by the body in response to, for example, chemotherapy drugs.
When serotonin binds to these receptors, the emesis reflex may be activated, resulting in feelings of nausea and the urge to vomit. 5-HT3 receptor antagonists such as Zofran and Zuplenz quell this emesis reflex by preventing serotonin from binding to the 5-HT3 receptors.12
Zuplenz and Generic Options
The 5-HT3 receptor antagonist ondansetron is sold in the U.S. under the brand names Zofran and Zuplenz. Zofran is available through prescription as an injection, oral tablet, orally disintegrating tablet and oral solution. Zuplenz is available through prescription as an oral film that dissolves on the tongue.
Other Zofran generic equivalent products have been approved by the FDA and have been available in the U.S. since 2006. 3
According to its package insert, Zofran is indicated for the prevention of nausea and vomiting associated with surgery, chemotherapy, or cancer radiotherapy. 4 Zuplenz is approved for similar indications.
Zofran and Zuplenz have been used “off-label” for the treatment of nausea and vomiting associated with pregnancy, although the U.S. Food and Drug Administration (FDA) has not approved these drugs for this indication.
Cases of serotonin syndrome, a potential side effect of having too much serotonin in the body, have been reported with the use of Zofran and Zuplenz, and some cases were fatal.
Zofran Contraindications and Warnings
The Zofran and Zuplenz package inserts contain several contraindications and warnings, summarized as follows:
- Zofran and Zuplenz should not be prescribed to patients who are also taking apomorphine, because the interaction of the drugs can cause profound hypotension and loss of consciousness.
- Patients who have exhibited hypersensitivity to other selective 5-HT3 receptor antagonists should discontinue the use of Zofran or Zuplenz immediately if hypersensitivity occurs.
- Zofran and Zuplenz should be avoided in patients with congenital long QT syndrome.
- Cases of serotonin syndrome, a potential side effect of having too much serotonin in the body, have been reported with the use of Zofran and Zuplenz, and some cases were fatal.
Symptoms of Serotonin Syndrome
The package inserts that accompany Zofran and Zuplenz advises doctors to monitor patients for signs of serotonin syndrome. You should seek medical attention immediately if you experience serotonin syndrome symptoms, such as:
- Tachycardia ( faster than normal heart rate)
- Labile blood pressure (blood pressure that fluctuates rapidly)
- Diaphoresis (excessive sweating)
- Myoclonus (involuntary twitching of muscles)
- Hyperreflexia (overly responsive reflexes)
- Seizures, with or without nausea, vomiting or diarrhea
Interactions with Other Drugs or Supplements
Taking more than one medication at a time is sometimes necessary, however, there may be an elevated risk of certain side effects.
Your physician can tell you about the risks and should therefore be consulted before you start taking more than one medication at a time. You should provide your physician a complete list of the medications you currently take or plan to begin taking; this list should include all of your prescription drugs plus all of your over-the-counter drugs, including vitamins and nutritional supplements.
Medicines that Can Cause Problems When Taken with Zofran and Zuplenz
Certain medications used in combination with Zofran or Zuplenz can cause serotonin syndrome. These other medications include:
SSRIs, SNRIs & MOAIs
Methylene blue, intravenous
Zofran: Medication Dosage
As stated in the package insert, the recommended adult oral dosage of Zofran for the prevention of nausea and vomiting associated with chemotherapy ranges from one 8 mg tablet or 10 mL of oral solution twice daily to three 8 mg tablets administered 30 minutes before the start of single-day chemotherapy, depending on the emetogenic potential (moderate or high, respectively) of the chemotherapy.
The package insert-recommended adult oral dosage of Zofran for the prevention of nausea and vomiting associated with cancer radiation therapy of a limited body area is one 8 mg tablet or 10 mL of oral solution thrice daily. For total body irradiation, the dosage is the same, except it should be administered one to two hours prior to each fraction of radiation therapy administered each day or – for single high-dose fraction radiotherapy to the abdomen – every eight hours after the first dose for one to two days, post-treatment.
The package insert-recommended adult oral dosage of Zofran for the prevention of nausea and vomiting following surgery is 16 mg given as two 8 mg tablets or 20 mL of oral solution one hour before induction of anesthesia.
A separate dosing schedule is recommended for the intravenous formulation of Zofran for the prevention of nausea and vomiting associated with emetogenic chemotherapy. 5
The Zuplenz package insert states that for highly emetogenic chemotherapy, the appropriate adult dose of Zuplenz are three 8 mg films taken 30 minutes before the commencement of chemotherapy. For moderately emetogenic chemotherapy, one 8 mg film should be taken 30 minutes before, followed by an 8 mg film eight hours later and an additional film every 12 hours for a day or two after the conclusion of chemotherapy is recommended. 6
For the prevention of nausea and vomiting associated with radiotherapy, the appropriate Zuplenz dose is one 8 mg film, taken three times a day. For postoperative nausea and vomiting, the appropriate Zuplenz dose is 16 mg, given as two 8 mg films 1 hour before the administration of anesthesia.
The Zuplenz package insert also notes that for patients with severely impaired liver function, the total daily dose of Zuplenz should not exceed 8 mg.
- Sanger GJ (September 2008). “5-hydroxytryptamine and the gastrointestinal tract: where next?” Trends in Pharmacological Sciences, Vol. 29:9, 465–71 (2008) (accessed April 1, 2015).
- “5-Hydroxytryptamine3 (5-HT3) Receptor Antagonists”. Oregon State University College of Pharmacy (2003).
- “Generic Zofran Availability,” available at https://www.drugs.com/availability/generic-zofran.html (accessed April 1, 2015).
- Zofran package insert, GlaxoSmithKline, https://www.gsksource.com/gskprm/en/US/adirect/gskprm?cmd=ProductDetailPage&product_id=1244175789338&featureKey=600624 (accessed April 1, 2015).
- Zofran injection for intravenous use package insert, GlaxoSmithKline, https://www.gsksource.com/pharma/content/dam/GlaxoSmithKline/US/en/Prescribing_Information/Zofran_Injection/pdf/ZOFRAN-INJECTION.PDF (accessed April 1, 2015).
- Zuplenz package insert, Galena Biopharma, http://zuplenz.com/pdf/Zuplenz-PI-long-version.pdf (accessed April 1, 2015).