Pharmacology · MU Sofia

55. Antiemetic drugs.

Covers the main antiemetic drug classes: dopamine D2 antagonists, 5-HT3 antagonists, anticholinergics, H1 antihistamines and others such as fosaprepitant and dexamethasone. It goes on to their mechanisms, a pharmacokinetic comparison table, side effects, interactions, therapeutic uses such as chemotherapy and postoperative nausea, and pregnancy and breastfeeding considerations, ending with recap questions.

Inside: 9 sections · 8 labelled pictures · 1 table · 10 flashcards · 4 min

Topic 54 of 93 in the MU Sofia syllabus for Pharmacology (Dental Medicine, Year 3). The free AceMed note covers it in 9 sections, about 514 words (4 min of reading), with 10 flashcards.

In this note

  1. Antiemetic Drugs
  2. Classification
  3. Pharmacodynamics
  4. Pharmacokinetics
  5. Side Effects
  6. Drug Interactions
  7. Therapeutic Use
  8. Pregnancy and Milk
  9. Recap Questions

Antiemetic Drugs

Antiemetic drugs are medications used to prevent or treat nausea and vomiting, which are often caused by factors such as chemotherapy, motion sickness, or gastrointestinal disorders. These drugs work by acting on specific receptors and neurotransmitter systems involved in the vomiting reflex.

Classification

  1. 1. Dopamine D2 receptor antagonists: Metoclopramide, Domperidone
  2. 2. Serotonin 5HT3 receptor antagonists: Ondansetron, Granisetron
  3. 3. Anticholinergic agents: Scopolamine
  4. 4. Histamine H1 receptor antagonists: Promethazine, Diphenhydramine
  5. 5. Others: Fosaprepitant, Dexamethasone

Pharmacodynamics

  • Dopamine D2 receptor antagonists (e.g. Metoclopramide, Domperidone) block dopamine receptors in the chemoreceptor trigger zone (CTZ) and gastrointestinal tract, thereby reducing nausea and vomiting.
  • Serotonin 5HT3 receptor antagonists (e.g. Ondansetron, Granisetron) inhibit serotonin at 5HT3 receptors in both the gastrointestinal tract and central nervous system, preventing the activation of the vomiting reflex.
  • Scopolamine blocks the action of acetylcholine in the vestibular system, helping to alleviate motion sickness and associated nausea and vomiting.
  • Histamine H1 receptor antagonists (e.g. Promethazine, Diphenhydramine) act by blocking histamine receptors in the inner ear and brain, reducing motion sickness and nausea.
  • Fosaprepitant is a neurokinin-1 (NK1) receptor antagonist used for chemotherapy-induced nausea and vomiting (CINV). Dexamethasone is a corticosteroid that also has anti-inflammatory effects, often used in combination with other antiemetics to prevent nausea in chemotherapy patients.

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