Dolasetron
Anzemet
5-HT3 receptor antagonist antiemetic
5-HT3 antagonist (prodrug → hydrodolasetron). Effective antiemetic but the most QT/dysrhythmia-prone of the class.
Indications
- •PONV (oral PONV still ok)
- •Chemotherapy N/V
Dosing
| Context | Adult | Pediatric |
|---|---|---|
| PONV | 12.5 mg IV near end of surgery | — |
Pharmacokinetics
Rapid conversion to active hydrodolasetron. Half-life ~7 h.
Side effects
- !QT/QRS prolongation (most of the class)
- !Headache
Contraindications
- ×IV use for chemotherapy N/V is CONTRAINDICATED (FDA — torsades); PONV IV dose still permitted
- ×Long QT
Clinical pearls
- ★FDA removed the IV chemo-N/V indication for torsades risk — the QT outlier of the 5-HT3 class.
- ★Correct K⁺/Mg²⁺; avoid stacking QT-prolonging drugs.
Other drugs in Antiemetics & Related
- Ondansetron
Blocks serotonin receptors at vagal afferents and chemoreceptor trigger zone.
- Metoclopramide
Central D2 antagonism at the chemoreceptor trigger zone (antiemetic). Peripherally, sensitizes upper-GI tissue to acetylcholine → increases lower esophageal sphincter tone, accelerates gastric emptying, speeds duodenal transit. Mild 5-HT4 agonism contributes to prokinesis.
- Droperidol
Potent central D2 antagonism at the chemoreceptor trigger zone. Also α-adrenergic blockade and mild GABA-A facilitation. Highly effective antiemetic and sedative — historically a key component of neuroleptanalgesia.
- Aprepitant
Selective antagonist at central neurokinin-1 receptors in the area postrema and nucleus tractus solitarius. Blocks substance-P-mediated emesis, particularly the delayed phase (24–72 h post-stimulus) where 5-HT3 antagonists lose efficacy.
- Granisetron
Blocks serotonin 5-HT3 receptors (central CTZ + peripheral vagal afferents). More selective + longer-acting than ondansetron.
- Promethazine
H1 antihistamine with anticholinergic + antidopaminergic activity → antiemetic + sedation + antihistamine effects.
Suggested reading
- •Stoelting & Hines, Pharmacology & Physiology in Anesthetic Practice, 6e
- •Miller's Anesthesia, 9e
- •FDA package insert
