24.2 : 化疗引起的恶心呕吐：5-HT_3 受体

Vomiting is a common side effect among individuals undergoing chemo and radiation therapy. In these patients, the damaged GI mucosa releases serotonin, which binds to receptors on vagal afferent nerves. This relays the signal towards the vomiting center, initiating vomiting reflex.

Also, the vomiting center and chemoreceptor trigger zone are rich in 5-HT₃ receptors, making them key targets for treating chemotherapy-induced nausea and vomiting or CINV.

Several antagonist drugs, including dolasetron, granisetron, ondansetron, and palonosetron selectively block 5-HT₃ receptors. These drugs are available as tablets, oral solutions, and intravenous formulations.

They act rapidly at the target site and effectively alleviate vomiting in patients undergoing chemotherapy and in postoperative and post-radiation cases.

Notably, palonosetron exhibits a higher affinity for 5-HT₃ receptors and a longer half-life of 40 hours.

Common adverse effects include headache, dizziness, and constipation. Additionally, high doses of dolasetron prolong the QT interval, causing arrhythmias.