Emesis serotonin antagonists

Granisetron is a serotonin antagonist. Serotonin (SHTs) receptors are also found in the chemotrigger zone of the medulla and in the gastrointestinal tract. Stimulation of them plays a role in emesis. 

The most widely used emetic is syrup of ipecac, containing the alkaloids, emetine and cq haeline. Emetine induces vomiting by activation of sensory neurons in the vagus and sympathetic nerves to the stomach and centrally in the medulla, possibly at the CTZ. The release of serotonin and SP may be involved as 5-HT3 and NKi receptor antagonists prevent emesis induced... 

An important advance in this field has been made by the discovery of selective serotonin (5-HT3) receptor antagonists that are effective inhibitors of cytotoxic drug-induced emesis in laboratory animals. The new agents have been found to be free of the undesirable side-effects associated with dopaminergic blockade and have shown significant protection from emesis in early clinical trials. 

Metoclopramide (Reglan, and others) is both a serotonin- and dopamine-receptor antagonist. Given alone, it is less effective than TV ondansetron. Given concurrently with dexamethasone and either the antianxiety agent lorazepam (Ativan, and others) or the antihistamine diphenhydramine (Benadryl, and others), it can control emesis due to high-dose cisplatin (120 mg/m2) in older adults. One study in older patients, however, found metoclopramide, dexamethasone, and diphenhydramine less effective than IV ondansetron combined with dexamethasone in patients taking > 50 mg/m2... 

Serotonin (5-HT3) antagonists are the mainstay today of drug treatment of acute chemotherapy-induced emesis [123]. However, the problem of delayed emesis has yet to be solved. Apparently dronabinol has not been tested so far as an add-on drug to HT3 antagonists to prevent this condition. 

Indications Chemotherapy-related emesis Category 5-HT3 antagonist Serotonin type 3 receptor antagonist... 

Bindley C, Blower P. Oral serotonin type 3-receptor antagonists for prevention of chemotherapy-induced emesis. Am J Health-Syst Pharm 2000 57 1685-1697. 

Darmani, N.A. (1998) Serotonin 5-HT3 receptor antagonists prevent cisplatin-induced emesis in Cryptotis parva a new experimental model of emesis, J. Neural Trans. 105 1143-1154. 

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