Dosing and uses of Antizol (fomepizole)
Adult dosage forms and strengths
injectable solution
- 1.5g/1.5mL
Methanol & Ethylene Glycol Poisoning
Load 15 mg/kg IV infusion over 30 min, THEn
10 mg/kg IV q12hr for 4 doses, THEN increase to 15 mg/kg q12hr
Maintain serum level of 8.6-24.6 mg/L
Treat until ethylene glycol or methanol levels are <20 mg/dL
Dialysis may also be required
Renal Impairment
Dialyzable: Yes
Follow dose recommendations for those not on hemodialysis (see above) at intervals appropriate for patients on hemodialysis schedule/duration
Dose at beginning of hemodialysis
- If <6 hr since last fomepizole dose: Do not administer the next dose
- If ≥6 hr since last fomepizole dose: Proceed with administering next fomepizole dose
Dose during hemodialysis
- Administer q4hr or as continuous IV infusion (1-1.5 mg/kg/hr)
Dose when hemodialysis is completed
- <1 hr: Do not administer
- 1-3 hr: Give 50% of next scheduled dose
- >3 hr: Administered next scheduled dose
Maintenance dose following hemodialysis
- Administer next scheduled dose 12 hr following last administered dose
Pediatric dosage forms and strengths
injectable solution
- 1.5g/1.5mL
Methanol & Ethylene Glycol Poisoning (Off-label)
Loading dose: 15 mg/kg IV, THEn
10 mg/kg IV q12hr for 4 doses, THEn
15 mg/kg IV q12hr until ethylene glycol or methanol levels reduce to <20 mg/dL
Renal Impairment
Dialyzable: Yes
Follow dose recommendations for those not on hemodialysis (see above) at intervals appropriate for patients on hemodialysis schedule/duration
Dose at beginning of hemodialysis
- If <6 hr since last fomepizole dose: Do not administer the next dose
- If ≥6 hr since last fomepizole dose: Proceed with administering next fomepizole dose
Dose during hemodialysis
- Administer q4hr or as continuous IV infusion (1-1.5 mg/kg/hr)
Dose when hemodialysis is completed
- <1 hr: Do not administer
- 1-3 hr: Give 50% of next scheduled dose
- >3 hr: Administered next scheduled dose
Maintenance dose following hemodialysis
- Administer next scheduled dose 12 hr following last administered dose
Antizol (fomepizole) adverse (side) effects
>10%
Headache (14%)
Nausea (11%)
1-10%
Bad/metallic taste (6%)
Dizziness (6%)
Drowsiness (6%)
Venous irritation
Transient elevations in LFTs (AST)
Backache
Nystagmus
Fever
Abdominal pain
<1%
Rash
Eosinophilia
Pregnancy and lactation
Pregnancy category: C
Lactation: excretion in milk unknown; use with caution
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Antizol (fomepizole)
Mechanism of action
Inhibits alcohol dehydrogenase, which catalyzes the metabolism of ethanol, methanol and ethylene glycol; has no effect upon CNS or need for monitoring levels (like EtOH currently)
Pharmacokinetics
Onset of action: 1.5-2 hr
Vd: 0.6-1.02 L/kg
Excretion: Urine
Administration
IV Preparation
Dilute in at least 100 mL of NS or D5W
Use within 24 hr
Storage
Inj concentrate solidifies if kept <25°C. Solidification & rethawing (in hand or water bath) does not affect efficacy, safety or stability.
Diluted solution is stable for at least 24 hr when stored at 20-25°C or refrigerated at 2-8°C
