Ondansetron 99614-02-5

Clinical uses

The 5-HT₃ receptor antagonists are the primary drugs used to treat and prevent chemotherapy-induced nausea and vomiting (CINV). A common use case is to give them intravenously about 30 minutes before commencement of a chemotherapy treatment. Ondansetron is also effective in controlling post-operative nausea and vomiting (PONV) and post-radiation nausea and vomiting, and is a possible therapy for nausea and vomiting due to acute or chronic medical illness or acute gastroenteritis. Although it is highly effective, the high cost of the brand-name version had limited its use to controlling PONV and CINV. It is also used off-label to treat hyperemesis gravidarum in pregnant women, but there is no conclusive data available on its safety in pregnancy, especially during the first trimester. It is also used to treat cyclic vomiting syndrome; although there have been no formal trials to confirm efficacy, case reports suggests it can be helpful in some cases. The drug is administered 1–3 times daily, depending on the severity of nausea and/or vomiting. The normal oral dose for adults and children over the age of 12 is 8 mg initially, followed by a second dose of 8 mg eight hours later. The drug is then administered once every 12 hours, usually for not more than 2–3 days. Following oral administration, it takes about 1. 5 to 2 hours to reach maximum plasma concentrations. This drug is removed from the body by the liver and kidneys. The clinical effect of ondansetron (and other drugs from the same group) can be potentiated by combining it with dexamethasone.

Investigational and off-label

Neuropsychiatric disorders

A 2006 double-blind, randomized controlled trial indicated that ondansetron may have value in the treatment of schizophrenia, as an adjunct to haloperidol. The study found the combination to significantly improve negative schizophrenia symptoms, and people taking both drugs experienced fewer of the adverse effects commonly associated with haloperidol. An earlier, smaller, open-label trial had found ondansetron to be useful in treating antipsychotic-induced tardive dyskinesia in people with schizophrenia, and the study patients also showed significant improvement in the disease's symptoms. Early studies have also examined ondansetron as a possible treatment for psychosis resulting from advanced Parkinson's disease. Its apparent benefits despite a lack of any significant antagonistic properties at dopamine receptors or the 5-HT2A receptor raises interesting questions about the etiology of psychosis. Hewlett and others found that the treatment of obsessive compulsive disorder with Ondansetron 1 mg three times daily was associated with a significant decrease in the Yale Brown Obsessive Compulsive scores in a small (n=8), 8-week, open-label study.

Substance use

Ondansetron lowers the cravings for alcohol, especially in early-onset alcoholics. In one cognitive-behavioral therapy study, ondansetron patients with early-onset alcoholism had fewer drinks per day and reported more days without drinking at all, as compared to the other groups in the study. Also of note, individuals with the LL genotype show significant improvements in alcohol misuse when treated with ondansetron, compared with individuals with the other genotypes of the 5HTTLPR polymorphism, who showed no improvement over placebo. Researchers at the Stanford University School of Medicine have demonstrated that ondansetron might be useful and effective for treating withdrawal symptoms of opioid addictions. Unlike the existing treatments methadone and buprenorphine, it is not itself an opioid. HTR3A which codes for the 5-HT₃ receptor emerged as the primary candidate, which suggested 5-HT₃ antagonist ondansetron as a possible treatment.

Postanesthetic shivering

Two small, placebo-controlled trials have been conducted to assess the efficacy of ondansetron for postanesthetic shivering, a common occurrence after surgery. Ondansetron was found to be as effective as pethidine (meperidine, Demerol) when given as a single IV dose before anesthesia.

Adverse effects

Ondansetron is a well-tolerated drug with few side effects. Constipation, dizziness and headache are the most commonly reported side effects associated with its use. There have been no significant drug interactions reported with this drug's use. It is broken down by the hepatic cytochrome P450 system and it has little effect on the metabolism of other drugs broken down by this system. On September 15, 2011, the FDA issued a Medwatch Safety Alert for Zofran (ondansetron) in patients with congenital Long QT syndrome, a heart arrhythmia. The FDA further required GlaxoSmithKline to conduct a thorough QT study to determine the degree to which Zofran may cause QT interval prolongation.

History

A vial of Zofran for intravenous injectionOndansetron was developed around 1984 by scientists working at Glaxo's laboratories in London. It is in both the imidazole and carbazole families of heterocyclic compounds. After several attempts the company successfully filed for U. S. patent protection for the drug in 1986. [&r=1&f=G&l=50&s1=4695578. PN. &OS=PN/4695578&RS=PN/4695578 U. S. Patent 4,695,578] was granted in September 1987 while [&r=1&f=G&l=50&s1=4753789. PN. &OS=PN/4753789&RS=PN/4753789 U. S. Patent 4,753,789] was granted in June 1988. [&r=1&f=G&l=50&s1=5578628. PN. &OS=PN/5578628&RS=PN/5578628 U. S. Patent 5,578,628], a divisional patent of [&r=1&f=G&l=50&s1=4753789. PN. &OS=PN/4753789&RS=PN/4753789 U. S. Patent 4,753,789], was granted on November 26, 1996. Ondansetron was granted FDA approval as Zofran in January 1991. Glaxo did pediatric research on Zofran's uses, and gained a patent extension as a result, extending U. S. exclusivity until December 24, 2006. The FDA subsequently approved the first generic versions in December 2006, with marketing approval granted to Teva Pharmaceuticals USA and SICOR Pharmaceuticals.

Brand names

Ondansetron is currently marketed by GlaxoSmithKline (GSK) under the trade name Zofran. Other manufacturers include Strativa Pharmaceuticals (Zuplenz), Cipla Ltd. (Emeset), Gedeon Richter Ltd. (Emetron), Korea United Pharmaceuticals (Emodan), Zentiva a. s. (Ondemet), Strides Arcolab (Setronax), Glenmark Generics Ltd. (India) (Ondansetron) and Novell Pharmaceutical Laboratories (Ondavell). On May 29, 2006, Baxter Healthcare received tentative approval to market its own label of Ondansetron Injection, USP,8 mg/50 mL and 32 mg/50 mL iso-osmotic sodium chloride solution, beginning upon expiration of GSK's patent later that year.