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Antiemetics are medications used to prevent or treat nausea and vomiting, which are common symptoms associated with various medical conditions, treatments, and surgeries. Regulatory agencies such as the U.S. Food and Drug Administration (FDA), European Medicines Agency (EMA), and other global authorities approve specific drugs based on rigorous safety and efficacy evaluations. This article reviews the major antiemetics approved by these agencies up to the year 2023.
Classifications of Antiemetics
Antiemetics are classified based on their mechanisms of action and the conditions they treat. The main classes include serotonin (5-HT3) receptor antagonists, dopamine antagonists, neurokinin-1 (NK1) receptor antagonists, antihistamines, and corticosteroids. Each class targets specific pathways involved in nausea and vomiting.
Major Approved Antiemetics Up to 2023
Serotonin (5-HT3) Receptor Antagonists
This class includes drugs that block serotonin receptors in the gastrointestinal tract and central nervous system, effectively preventing chemotherapy-induced nausea and postoperative vomiting.
- Ondansetron – Approved by the FDA in 1991, widely used for chemotherapy, radiation therapy, and post-surgical nausea.
- Granisetron – Approved by the FDA in 1993, used similarly to ondansetron.
- Dolasetron – Approved in 1992, though some restrictions exist due to cardiac side effects.
- Palonosetron – Approved in 2003, notable for its longer half-life and effectiveness.
Dopamine Antagonists
This group includes drugs that block dopamine receptors in the brain’s chemoreceptor trigger zone, often used for nausea related to gastrointestinal disorders, migraines, and chemotherapy.
- Prochlorperazine – Approved by the FDA in 1950s, commonly used for nausea and psychotic disorders.
- Metoclopramide – Approved in 1980, also used to enhance gastric emptying.
- Dopamine antagonists in this class have some risk of extrapyramidal side effects.
Neurokinin-1 (NK1) Receptor Antagonists
This newer class blocks substance P from binding to NK1 receptors, providing effective control over delayed nausea and vomiting, especially in chemotherapy settings.
- Aprepitant – Approved by the FDA in 2003, often combined with other antiemetics.
- Fosaprepitant – An IV prodrug of aprepitant, approved in 2008.
- Rolapitant – Approved in 2015, with a longer duration of action.
Antihistamines
These drugs block histamine receptors and are mainly used for motion sickness and vertigo.
- Dimenhydrinate – Approved in the mid-20th century, common over-the-counter medication.
- Meclizine – Approved in the 1940s, used for vertigo and motion sickness.
- Diphenhydramine – Widely available OTC, also used for allergic reactions.
Corticosteroids
Used as adjuncts in chemotherapy-induced nausea, corticosteroids like dexamethasone have shown effectiveness in reducing nausea.
- Dexamethasone – Approved for various indications, including nausea prevention in chemotherapy.
Regulatory Considerations and Safety
Approval by agencies like the FDA and EMA involves rigorous evaluation of safety, efficacy, and manufacturing standards. Over the years, some drugs have been withdrawn or restricted due to adverse effects, such as cardiac arrhythmias or extrapyramidal symptoms. Continuous monitoring and post-marketing surveillance are crucial to ensure patient safety.
Conclusion
Up to 2023, a variety of antiemetics have been approved for clinical use across different indications. Advances in understanding the mechanisms of nausea and vomiting have led to the development of targeted therapies, improving patient outcomes. Ongoing research and regulatory oversight continue to shape the landscape of antiemetic therapy, ensuring safety and effectiveness for patients worldwide.