fomepizole

Absorption: IV administration results in complete bioavailability.

Distribution: Distributes to total body water.

Metabolism/Excretion: Mostly metabolized, less than 1–3.5% excreted unchanged in urine.

Half-Life: Unknown

Time/Action Profile ⬆ ⬇

ROUTE	ONSET	PEAK	DURATION
IV	rapid	end of infusion	12 hr

Contraind./Precautions ⬆ ⬇

Contraindicated in:

Hypersensitivity to fomepizole or other pyrazoles.

Use Cautiously in:

OB: Use during pregnancy only if potential maternal benefit justifies potential fetal risk;
Lactation: Use while breastfeeding only if potential maternal benefit justifies potential risk to infant;
Pedi: Safety and effectiveness not established in children;
Geri: Safety and effectiveness not established in older adults.

Adv. Reactions/Side Effects ⬆ ⬇

GI: nausea

Neuro: headache, dizziness, drowsiness, dysgeusia

Misc: allergic reactions (mild rash, eosinophilia)

Interactions ⬆ ⬇

Drug-drug:

None reported.

Route/Dosage ⬆ ⬇

IV (Adults ): Loading dose: 15 mg/kg, then 10 mg/kg every 12 hours for four doses, then 15 mg/kg every 12 hours until levels of methanol or ethylene glycol are undetectable or <20 mg/dL and patient is asymptomatic with normal pH.Patients requiring hemodialysis (beginning): wait at least 6 hr after initiating hemodialysis to give next scheduled dose; during hemodialysis: give dose every 4 hr; when hemodialysis is completed: if time between last dose and end of dialysis is <1 hr, do not administer dose at the end of hemodialysis, if time between last dose and end of hemodialysis is 1–3 hr give 1/2 of next scheduled dose, if time between last dose and end of hemodialysis is >3 hr give next scheduled dose, Treatment is continued until levels of methanol or ethylene glycol are undetectable or <20 mg/dL and patient is asymptomatic with normal pH.

Availability ⬆ ⬇

(Generic available)

Solution for injection: 1 g/mL

Assessment ⬆ ⬇

Monitor for signs and symptoms of accumulation of toxic metabolites, glycolic and oxalic acids (ethylene glycol) and formic acid (methanol) (metabolic acidosis, nausea/vomiting, seizures, stupor, coma, calcium oxaluria, acute tubular necrosis, blindness, death) prior to and frequently during therapy.
Monitor for signs and symptoms of allergic reaction (mild rash, eosinophilia) during infusion.
Assess ECG periodically during therapy; acidosis and electrolyte imbalances may affect cardiovascular system. Electroencephalography may be required in comatose patients.

Lab Test Considerations:

Monitor serum levels of ethylene glycol and/or methanol. Lethal dose of ethylene glycol in humans is 1.4 mL/kg. Lethal dose of methanol in humans is 1–2 mL/kg.
- Monitor arterial blood gases, pH, electrolytes, anion gap, BUN, serum creatinine, and urinalysis frequently during therapy. Poisoning may cause metabolic acidosis, acute renal failure (ethylene glycol), adult respiratory distress syndrome, visual disturbances (methanol) and hypocalcemia.
- Monitor serum and urine ethylene glycol concentrations and for presence of urinary oxalate crystals frequently in patients poisoned with ethylene glycol.
- Monitor serum methanol concentrations frequently in patients poisoned with methanol.
- Fomepizole may cause transiently ↑ serum transaminases. Monitor hepatic enzymes periodically during therapy.
- Monitor WBC periodically during therapy. May cause eosinophilia.

Implementation ⬆ ⬇

Do not confuse fomepizole with omeprazole.
Supportive therapy with fluids and sodium bicarbonate, supplementation with potassium, and calcium, and oxygen are usually necessary. Hemodialysis is needed if patient is anuric, has severe metabolic acidosis or azotemia, or has high ethylene glycol or methanol concentrations (≥50 mg/dL).
- Begin treatment with fomepizole immediately upon suspicion of ethylene glycol or methanol ingestion based on patient history and/or anion gap metabolic acidosis, increased osmolar gap, visual disturbances, oxalate crystals in urine OR documented serum ethylene glycol or methanol concentrations >20 mg/dL.
- Discontinue fomepizole when ethylene glycol or methanol concentrations are undetectable or have been reduced <20 mg/dL, and patient is asymptomatic with normal pH.
Intermittent Infusion: If fomepizole solution becomes solid in vial, liquefy by running vial under warm water or holding in hand. Solidification does not affect efficacy, safety, or stability. Diluent: Withdraw dose from vial and inject into at least 100 mL of 0.9% NaCl or D5W. Mix well. Do not administer solutions that are hazy, discolored, or contain a precipitate. Solution is stable for 24 hrs if refrigerated or at room temperature; do not use beyond 24 hrs. Avoid using polycarbonate syringes or polycarbonate-containing needles (including polycarbonate filter needles) during dilution.
Rate: Infuse slowly over at least 30 min.

Patient/Family Teaching ⬆ ⬇

Explain purpose of fomepizole to patient.
Advise patient to notify health care professional if signs and symptoms of allergic reaction occur.
Advise patient to notify health care professional if pregnancy is planned or suspected or if breastfeeding.

Evaluation/Desired Outcomes ⬆ ⬇

Ethylene glycol or methanol concentrations <20 mg/dL or undetectable, and asymptomatic patient with normal pH. Prevention of organ damage.

Canadian Brand Names ⬆ ⬇

Code ⬆

NDC Code

0517- American Regent, Inc.
- 0517-0710- fomepizole
  - 0517-0710-01- 1 VIAL in 1 CARTON (0517-0710-01) > 1.5 mL in 1 VIAL

67457- Mylan Institutional LLC
- 67457-211- Fomepizole
  - 67457-211-02- 1 VIAL, GLASS in 1 CARTON (67457-211-02) > 1.5 mL in 1 VIAL, GLASS

68475- Navinta LLC
- 68475-510- Fomepizole
  - 68475-510-01- 1 VIAL in 1 CARTON (68475-510-01) > 1.5 mL in 1 VIAL

70710- Zydus Pharmaceuticals USA Inc.
- 70710-1478- Fomepizole
  - 70710-1478-1- 1 VIAL in 1 CARTON (70710-1478-1) > 1.5 mL in 1 VIAL

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Pronunciation ⬇

Classifications ⬆ ⬇

Indications ⬆ ⬇

Action ⬆ ⬇

Pharmacokinetics ⬆ ⬇