How Do Antiemetic Selective 5-HT3 Antagonist Work?

Antiemetic selective serotonin receptor (5-HT3) antagonists (also called serotonin blockers) are a class of medications used to prevent or treat nausea and vomiting in children and adults related to chemotherapy use and radiation therapy and the effects of postoperative anesthesia. They are particularly effective in treating acute emesis, occurring in the first 24 hours following chemotherapy. Chemotherapy-induced nausea and vomiting affect 70% to 80% of the people with cancer and have a significant impact on the individual and healthcare resources.

Antiemetic 5-HT3 antagonists are administered via oral and intravenous routes; they are usually taken approximately 1 hour before the start of chemotherapy with or without food.

Antiemetic 5-HT3 antagonists work in the following ways:

• Vomiting is controlled by the vomiting center in the brain, which is activated by triggers such as strong smell, thoughts and motion.
• The cells that line the gastrointestinal tract release serotonin (a chemical messenger responsible for transmitting vomiting signals) when they are damaged by chemotherapy or radiotherapy.
• This serotonin binds to the serotonin receptors present on the nerves that transmit impulses to the vomiting center located in the brain, which in turn activates the vomit reflex.
• Antiemetic 5-HT3 antagonists block the serotonin both peripherally, on gastrointestinal vagal nerve terminals, and centrally in the chemoreceptor trigger zone; this blockade results in powerful antiemetic effects.
• In addition, they produce a calming effect on the brain that leads to slight drowsiness.

Antiemetic 5-HT3 antagonists are used in conditions such as:

• Chemotherapy-induced nausea and vomiting
• Postoperative nausea and vomiting
• Radiation-induced nausea and vomiting
• Hyperemesis gravidarum (an extreme form of morning sickness that causes severe nausea and vomiting during pregnancy)
• Cholestatic pruritus (sensation of itching because of any liver disease)

Common side effects include:

• Headache
• Constipation
• Fatigue
• Drowsiness
• Dizziness (feeling faint, weak, or unsteady)
• Dry mouth
• Loss of appetite
• Malaise
• Pruritis (itching)

Other rare side effects include:

• Blurred vision
• Fast, slow, or irregular heartbeat
• Confusion
• Unusual weakness
• Hallucinations (involve hearing, seeing, feeling, smelling, or even tasting things that are not real)
• Hypertension/hypotension
• Urinary retention
• Twitching muscles
• Restlessness
• Agitation
• Elevated liver function test results

Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

Drug names include:                              

• Akynzeo
• Aloxi
• Anzemet
• Dolasetron
• Fosnetupitant
• Granisetron
• Granisol Oral Solution
• Netupitant/palonosetron
• Ondansetron
• Palonosetron
• Sancuso
• Sustol
• Zofran
• Zofran ODT
• Zuplenz