ExoticRx · exoticrx.com/drugs/fomepizole-4-mp
US brand names:Antizol-Vet
Fomepizole (4-MP) is dosed at 20 mg/kg IV 20mg/kg load; 15 at 12h,24h; 5 at 36h in dogs, per ANTIZOL-VET - Fomepizole Liquid [US Product Label for Dogs]. Paladin Labs (USA), Inc; 2017. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=c045b5a8-b220-4f0a-a831-155b29c19454 — Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.585 (2026-08-01).. Verify against current literature before clinical use.
Competitive inhibitor of alcohol dehydrogenase, preventing metabolism of ethylene glycol to toxic metabolites (glycolaldehyde, glycolic acid, oxalate).
Most effective within 8-12 hours of ethylene glycol ingestion in dogs (3 hours in cats). Cats require higher doses. Very expensive but life-saving.
Species references:All Cat (Domestic) drugsAll Dog (Domestic) drugs
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A dog/cat sample is shown here. Cited dosing for all 2 species — reptiles, birds, pocket pets, livestock, and equine — is free on the per-species pages above. Pro adds the weight-based calculator for every species.
| Species | Route | Dose | Frequency | Evidence | Source |
|---|---|---|---|---|---|
| Dog (Domestic) | IV | 20 mg/kg | 20mg/kg load; 15 at 12h,24h; 5 at 36h | Strong | ANTIZOL-VET - Fomepizole Liquid [US Product Label for Dogs]. Paladin Labs (USA), Inc; 2017. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=c045b5a8-b220-4f0a-a831-155b29c19454 — Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.585 (2026-08-01). |
| Cat (Domestic) | IV | 125 mg/kg | Loading 125mg/kg, then 31.25mg/kg q12h x 3 doses | Moderate | Connally HE, Thrall MA, Hamar DW. Safety and efficacy of high-dose fomepizole compared with ethanol as therapy for ethylene glycol intoxication in cats. J Vet Emerg Crit Care. 2010;20(2):191-206. doi:10.1111/j.1476-4431.2009.00492.x — Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.585 (2026-08-01). |
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