Ondansetron

Ondansetron, marketed under the brand name Zofran, is a medication used to prevent nausea and vomiting caused by cancer chemotherapy, radiation therapy, or surgery. It is also useful in gastroenteritis. It has little effect on vomiting caused by motion sickness. It can be given by mouth, or by injection into a muscle or into a vein. Ondansetron, marketed under the brand name Zofran, is a medication used to prevent nausea and vomiting caused by cancer chemotherapy, radiation therapy, or surgery. It is also useful in gastroenteritis. It has little effect on vomiting caused by motion sickness. It can be given by mouth, or by injection into a muscle or into a vein. Common side effects include diarrhea, constipation, headache, sleepiness, and itchiness. Serious side effects include QT prolongation and severe allergic reaction. It appears to be safe during pregnancy but has not been well studied in this group. It is a serotonin 5-HT3 receptor antagonist. It does not have any effect on dopamine receptors or muscarinic receptors. Ondansetron was patented in 1984 and approved for medical use in 1990. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system. It is available as a generic medication. The wholesale cost of the injectable form in the developing world is about US$0.10 to US$0.76 per dose. In the United States it costs about US$1.37 per tablet. In 2016 it was the 91st most prescribed medication in the United States with more than 8 million prescriptions. Although an effective antiemetic agent, the high cost of brand-name ondansetron initially limited its use to controlling postoperative nausea and vomiting and chemotherapy-induced nausea and vomiting. The 5-HT3 receptor antagonists are the primary medications used to treat and prevent chemotherapy-induced nausea and vomiting and radiotherapy-induced nausea and vomiting. A number of medications including ondansetron appear to be effective in controlling postoperative nausea and vomiting. It is more effective than metoclopramide, and less sedating than cyclizine or droperidol. Ondansetron is used off-label to treat morning sickness and hyperemesis gravidarum of pregnancy. It is typically used after trials if other drugs have failed. There appears to be a low risk of harm to the baby with use during pregnancy, though there may be an increase in heart problems among the babies. Ondansetron is in pregnancy category B in the US. It is not known if ondansetron is excreted in breast milk.