Nausea 5HT3 receptor antagonists

One of the major side-effects of cytotoxic chemotherapy is nausea and vomiting. It is essential therefore to control this with prophylactic antiemetic therapy. A number of agents are currently available and are effective at controlling chemotherapy-induced emesis. The most potent of these are 5HT3-receptor antagonists that include ondansetron, granisetron and palonosetron. 

The use of cytotoxic drugs with a high level of emetogenicity requires the prophylactic administration of a combination of a 5HT3-receptor antagonist and a corticosteroid to prevent the onset of acute nausea and vomiting (i.e. within the first 24 hours). 

There is little evidence supporting the use of 5HT3-receptor antagonists beyond the first 24 hours, and corticosteroids appear to be the most effective component of antiemetic regimens used to prevent delayed nausea and vomiting (American Society of Clinical Oncology et ah, 2006). 

Tropisetron is marketed outside the U.S. as a 5HT3 receptor antagonist for nausea, but it has a7-nicotinic agonist effects in the same concentration range. Tropisetron normalizes P50 inhibition in schizophrenics, with the effect primarily occurring in the nonsmoking subjects (Koike et al., 2005). 

Managemeut of adverse drug reactious 5HT3 receptor antagonists The addition of ondansetron and ketorolac to fentanyl was associated with less nausea and vomiting and dizziness in 135 patients undergoing thyroid surgery [76 ]. 

Ondansetron is a 5HT3 antagonist, blocking serotonin receptors in the central nervous system and the gastrointestinal tract. It is useful in the management of postoperative nausea and vomiting associated with cytotoxics. 

---