Dolasetron
Dolasetron mesylate
Also known as: Anzemet · Anemet · Zamanon · Dolasetron mesylate · Hydrodolasetron · Reduced dolasetron
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Anti-emetic, particularly for patients receiving chemotherapeutics | 0.6 mg/kg IV once daily | IV | q24h | — | 🌎 NA |
| General anti-emetic | 0.6 mg/kg IV q24h or 0.5 mg/kg PO, SC or IV q24h | IV/PO/SC | q24h | — | 🌎 NA |
| Vomiting disorders | 0.6-1 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
| Prevent vomiting | 0.6 mg/kg IV or PO once daily | IV/PO | q24h | — | 🌎 NA |
| Treat vomiting | 1 mg/kg PO or IV once daily | PO/IV | q24h | — | 🌎 NA |
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Anti-emetic, particularly for patients receiving chemotherapeutics | 0.6 mg/kg IV once daily | IV | q24h | — | 🌎 NA |
| Vomiting disorders | 0.6-1 mg/kg PO q12h | PO | q12h | — | 🌎 NA |
| Prevent vomiting | 0.6 mg/kg IV or PO once daily | IV/PO | q24h | — | 🌎 NA |
| Treat vomiting | 1 mg/kg PO or IV once daily | PO/IV | q24h | — | 🌎 NA |
| General anti-emetic | 0.6 mg/kg IV q12h or 0.6-1 mg/kg PO q12h | IV/PO | q12h | — | 🌎 NA |
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Dolasetron is a potent 5-HT3 receptor antagonist utilized primarily as an antiemetic in veterinary medicine. It is particularly effective for managing severe nausea and vomiting associated with cancer chemotherapy in dogs and cats.
- Dosing Convenience: Unlike ondansetron, which often requires multiple daily doses, dolasetron can typically be administered once daily.
- Formulation Challenges: While the injectable form is highly practical for in-hospital use, the commercially available human oral tablets (50 mg and 100 mg) are too large for direct administration to most small animals. Consequently, oral use usually requires compounding.
Clinical Pearl: Due to cost and formulation constraints, other antiemetics like maropitant (Cerenia) or ondansetron are often preferred for routine outpatient use, reserving dolasetron for refractory cases or specific chemotherapy protocols.
Mechanism of action
Dolasetron exerts its anti-nausea and antiemetic effects by selectively antagonizing 5-hydroxytryptamine 3 (5-HT3) receptors.
- Peripheral Pathway: Chemotherapy and severe GI insults cause the release of serotonin from mucosal enterochromaffin cells in the small intestine. Serotonin binds to 5-HT3 receptors on vagal afferent nerve terminals, sending emetogenic signals to the brain. Dolasetron blocks this interaction.
- Central Pathway: Dolasetron also blocks 5-HT3 receptors located directly within the Chemoreceptor Trigger Zone (CRTZ) in the central nervous system.
Once administered, dolasetron is rapidly converted by carbonyl reductase into its active metabolite, hydrodolasetron, which is primarily responsible for the pharmacological effects.
Safety & warnings
Contraindications
- Known hypersensitivity to dolasetron
- Atrioventricular (AV) block II to III
- Markedly prolonged QTc interval
Adverse effects
- Dose-related ECG interval prolongation (PR, QTc, JT prolongation, and QRS widening)
- Headache (reported in humans)
- Dizziness (reported in humans)
Precautions
Use with extreme caution in patients susceptible to cardiac conduction interval prolongation. This includes patients with hypokalemia, hypomagnesemia, congenital QT syndrome, those receiving anti-arrhythmic drugs or diuretics that induce electrolyte abnormalities, or those who have received a cumulative high dose of anthracycline chemotherapy. Note that 5-HT3 antagonists are generally ineffective for vomiting associated with feline hepatic lipidosis or mechanical GI obstruction.
Drug interactions
May reduce the clearance and increase blood levels of hydrodolasetron
May reduce the clearance and increase blood levels of hydrodolasetron
May reduce the clearance and increase blood levels of hydrodolasetron
Can reduce hydrodolasetron blood levels
Can reduce hydrodolasetron blood levels
Monitoring
- Efficacy (resolution of nausea and vomiting)
- Heart rhythm (ECG) in at-risk patients (e.g., those with electrolyte imbalances or on arrhythmogenic drugs)
Pharmacokinetics
Half-life
Absorption
Rapidly absorbed after oral administration. In humans, oral bioavailability is approximately 75%.
Distribution
In dogs, the volume of distribution for the active metabolite (hydrodolasetron) is 8.5 L/kg.
Metabolism
Rapidly reduced via carbonyl reductase to hydrodolasetron (reduced dolasetron), which is the primary active compound. Partially metabolized in the liver.
Elimination
In dogs, total body clearance is 25 mL/min/kg. In humans, 50-60% is excreted unchanged into the urine. Clearance may be reduced in severe renal or hepatic impairment.
Overdose
Data on overdosage is very limited.
- Clinical Signs: In humans, a massive overdose (13 mg/kg) resulted in severe hypotension and dizziness.
- Treatment: Manage overdoses with supportive therapy, including IV fluids and pressors if hypotension occurs.
- Toxicity: Lethal intravenous doses in mice and rats were 160 mg/kg and 140 mg/kg, respectively.
Available products
Formulations
- Tablets
- Injection
Human-labeled
- Dolasetron Tablets: 50 mg & 100 mg (Anzemet)
- Dolasetron Injection: 20 mg/mL in ampules and vials (Anzemet)
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Tablets should be stored at room temperature 20-25°C (68-77°F) and protected from light. Injection should be stored at room temperature 20-25°C (68-77°F) with excursions permitted to 15-30°C (59-86°F); protect from light. After dilution in compatible IV fluids, the injectable is stable under normal lighting at room temperature for 24 hours, or 48 hours if refrigerated.
Client information
What is Dolasetron? Dolasetron is a strong anti-nausea medication, most commonly used to prevent or treat severe vomiting associated with chemotherapy in pets.
- Administration: The injectable form is usually given by your veterinarian at the clinic. If you are sent home with oral medication, it will likely be specially compounded (remade into a smaller pill or liquid) by a pharmacy, as the standard human tablets are too large for dogs and cats.
- Side Effects: This medication is generally very well tolerated by pets.
- When to call the vet: Contact your veterinarian if your pet continues to vomit despite the medication, or if you notice extreme lethargy, weakness, or collapse.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.