Vetdrugs 2.0Metamizole sodium, also called dipyrone or analgin, is a pyrazolone analgesic and antipyretic prodrug. Veterinary applications include equine fever and selected painful conditions in other species. Its pharmacology includes important central effects, while the clinical evidence for particular analgesic or antispasmodic applications varies by species and disorder.
Group
Pyrazolone analgesic and antipyretic
Mechanism of Action
Metamizole is converted to active pyrazolone metabolites that modify central pain and thermoregulatory pathways. Reduced prostaglandin-associated signaling contributes to antipyresis and analgesia; cannabinoid, opioid and other central mechanisms have also been proposed. Effects on smooth-muscle calcium signaling may contribute to spasmolytic activity, but the relative importance of these pathways remains incompletely established.
Dose Rates
Horses
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Pyrexia | 30 mg/kg | IV | Every 12 h | Up to 3 days |
Dogs
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Analgesia | 50 mg/kg | IV, IM, SC | Every 12 h | Parenteral small-animal regimen; IM and SC injections can be irritating. Do not apply these routes to an IV-only product. |
Indications
- Control of fever in horses using an appropriate veterinary preparation.
- Treatment of selected acute pain in dogs, often within a multimodal analgesic plan, with condition-specific evidence.
- Adjunctive relief of selected equine visceral pain or intestinal spasm, with limited controlled evidence for a distinct antispasmodic benefit.
Contraindications
- Hypersensitivity; avoid when gastrointestinal ulceration or significant renal compromise makes analgesic treatment unsafe.
Interactions
- Avoid concurrent NSAIDs, corticosteroids and other ulcerogenic drugs.
Adverse effects
- Injection irritation; gastrointestinal ulceration or colitis can occur.
- Platelet function may be inhibited; agranulocytosis is a recognised human risk, without an established equine incidence.
Toxicity
Provide supportive treatment for overdose and monitor gastrointestinal bleeding, renal function and blood counts.
Preparations
| Preparation | Form | Strength | Route |
|---|---|---|---|
| Zimeta 500 mg/mL injection Equine antipyretic product; administer by IV injection. | Injection | 500 mg / mL | IV |
Monitoring and Administration
Use the formulation-specific route. The equine 500 mg/mL product is for IV use; IM/SC administration can irritate tissue.
Monitor hydration, gastrointestinal signs, protein loss, bleeding and temperature.