Drug of choice for vomiting
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drug of choice antiemetics vomiting nausea treatment
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antiemetic drugs mechanism classification ondansetron metoclopramide promethazine
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Drug of Choice for Vomiting
There is no single universal drug of choice — the preferred antiemetic depends on the clinical context (etiology, setting, patient population).
Antiemetic Drug Classes
| Class | Examples | Primary Use |
|---|---|---|
| 5-HT3 antagonists | Ondansetron, Granisetron | Chemotherapy-induced, post-op, general |
| Dopamine D2 antagonists | Metoclopramide, Prochlorperazine, Domperidone | Gastroparesis, general N&V |
| H1 antihistamines | Promethazine, Meclizine, Dimenhydrinate | Motion sickness, vestibular causes |
| Muscarinic M1 antagonists | Scopolamine | Motion sickness |
| NK1 antagonists | Aprepitant | Chemotherapy-induced (highly emetogenic) |
| Cannabinoids | Dronabinol | Chemo-induced, refractory cases |
| Phenothiazines | Chlorpromazine | Severe intractable vomiting |
Drug of Choice by Context
| Clinical Situation | Preferred Agent |
|---|---|
| General/acute vomiting | Ondansetron (5-HT3 antagonist) — most widely used first-line |
| Chemotherapy-induced N&V (CINV) | Ondansetron + Dexamethasone ± Aprepitant (NK1) for highly emetogenic regimens |
| Post-operative N&V (PONV) | Ondansetron ± Dexamethasone |
| Pregnancy (morning sickness) | Pyridoxine (Vit B6) ± Doxylamine (first-line); Ondansetron (second-line) |
| Motion sickness | Scopolamine (transdermal) or Meclizine |
| Gastroparesis | Metoclopramide (prokinetic + antiemetic) |
| Cirrhosis/liver disease | Ondansetron (max 8 mg/day); monitor QTc (Palliative Care in Decompensated Cirrhosis, p. 22) |
| Vestibular/labyrinthine | Meclizine or Promethazine |
| Opioid-induced | Ondansetron or Prochlorperazine |
| Metabolic/refractory | Haloperidol, Chlorpromazine |
Key Points
- Ondansetron is the most commonly used first-line antiemetic in clinical practice due to its favorable side-effect profile and broad applicability.
- Metoclopramide is preferred when a prokinetic effect is also needed (e.g., gastroparesis, diabetic nausea).
- All antiemetics that prolong QTc (ondansetron, domperidone, prochlorperazine) require ECG monitoring in at-risk patients (Chronic Nausea and Vomiting, p. 29).
- Extrapyramidal side effects (EPS) are a concern with dopamine antagonists (metoclopramide, prochlorperazine) — use with caution in elderly patients.
- Promethazine is contraindicated in children <2 years due to risk of respiratory depression.
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