Parenteral Manual


Disclaimer: Official controlled document is the CHEO online copy. It is the responsibility of user to ensure that any paper copy version is the same as the online version before use.

Alternate Name(s): 
Alcohol dehydrogenase inhibitor
Original Date: 
March 2007
Revised Date: 
September 2011
  • Antidote for ethylene glycol (such as antifreeze) or methanol (such as windshield washer fluid) poisoning
Reconstitution and Stability: 
  • Available as 1000 mg/mL (1 g/mL) solution
  • Store vials at room temperature.
  • Undiluted fomepizole solidifies at temperatures < 25°C : solidification does not affect efficacy, safety or stability.
  • To prevent solidification during preparation, place fomepizole vial, IV minibag and syringe in a clean sealable plastic bag. Immerse in warm water for several minutes prior to mixing (fomepizole may re-solidify and clog syringe needle during preparation unless all supplies are adequately warmed).
  • If solidification occurs, liquefy by running vial under warm water or by holding in the hand.
  • Mix dose in 100 mL NS or D5W.  Diluted solution is stable for 48 hrs at room temperature or refrigerated.

Solution compatible: NS, D5W


Incompatible: Do not mix with any other medication



(For approved routes of administration by nursing personnel, refer to Policy for the Administration of Intravenous Medications.)

IV Direct NO
IV Intermittent Infusion

Usual dilution: dilute dose in 100 mL of NS or D5W
Infusion time: over 30 minutes

IV Continuous Infusion

Yes, during hemodialysis : 1-1.5 mg/kg/hour

Usual dilution: 10 mg/mL




(For neonatal dosages, refer to Neonatal IV Drug Manual.)


  • Safety and efficacy has not been established in children
  • A limited number of case reports involving infants and children 8 months to 13 years of age have used the same dosage as those recommended for adults.

Adults NOT ON hemodialysis

  • Initial: 15 mg/kg loading dose
  • Maintenance: 10 mg/kg every 12 hrs for 4 doses (48 hrs) starting 12 hours after loading dose given; then increase to 15 mg/kg every 12 hrs for all subsequent doses.
  • Discontinuation: serum ethylene glycol or methanol are undetectable or have been reduced below 20 mg/dL (ethylene glycol < 3.2 mmol/L or methanol < 6.2 mmol/L) and the patient is asymptomatic with normal pH.

Adults ON hemodialysis

  • Before dialysis:
    • If < 6 hrs since last dose: Do NOT administer dose
    • If > 6 hrs since last dose: Administer next scheduled dose
  • During dialysis:
    • Administer doses every 4 hrs or as continuous infusion at 1-1.5 mg/kg/hr
  • Post dialysis:
    • Dose at the time hemodialysis is completed depends upon the time between the last dose and the end of hemodialysis:
      • < 1 hr: Do NOT administer at the end of hemodialysis
      • 1-3 hrs: Administer 50% of next scheduled dose
      • > 3 hrs: Administer next scheduled dose
    • Maintenance dose off hemodialysis
      • Give next scheduled dose 12 hrs from last administered dose

 Dosage adjustment in renal impairment

  • Fomepizole is substantially excreted by the kidney and the risk of toxic reaction to this drug may be increased in patients with impaired renal function. No dosage recommendations for patients with impaired renal function have been established.
Potential hazards of parenteral administration: 
  • Venous irritation, phlebitis if given too rapidly or undiluted
  • Mild allergic reaction: transient rash, eosinophillia
  • CNS: headache, dizziness, drowsiness
  • GI: nausea, bad/metallic taste
  • Rare: tachycardia, bradycardia, seizure, fever
  • Hemodialysis should be considered in addition to fomepizole in the case of renal failure, significant or worsening metabolic acidosis or a measured ethylene glycol or methanol concentration equal or greater than 50 mg/dL (ethylene glycol > 8.1 mmol/L and methanol > 15.6 mmol/L).
  • Monitor vital signs, arterial blood gases, acid-base status, urinary oxalate, anion and osmolar gaps, clinical signs and symptoms of toxicity (arrhythmias, seizures, coma), serum and urinary ethylene glycol or serum methanol level depending upon agent ingested, formic acid level (methanol ingestion)

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