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Fomepizole



Fomepizole
Identifiers
CAS number 7554-65-6
SMILES CC1C=NNCC1
Properties
Molecular formula C4H6N2
Molar mass 82.10 g/mol
Density 0.99 g/cm3
Boiling point

99-100 °C

Hazards
Flash point 96.0 °C<
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

Fomepizole or 4-methylpyrazole is indicated for use as an antidote in confirmed or suspected methanol or ethylene glycol poisoning. It may be used alone or in combination with hemodialysis. {03}

Additional recommended knowledge

Contents

Uses

Fomepizole is a competitive inhibitor of alcohol dehydrogenase, the enzyme that catalyzes the initial steps in the metabolism of ethylene glycol and methanol to their toxic metabolites. Ethylene glycol is first metabolized to glycolaldehyde which then undergoes further oxidation to glycolate, glyoxylate, and oxalate. It is glycolate and oxalate that are primarily responsible for the metabolic acidosis and renal damage that are seen in ethylene glycol poisoning. Methanol is first metabolized to formaldehyde and then undergoes subsequent oxidation via formaldehyde dehydrogenase to become formic acid. It is formic acid that is primarily responsible for the metabolic acidosis and visual disturbances that are associated with methanol poisoning.

Dosage

Fomepizole distributes rapidly into total body water. The volume of distribution is between 0.6 and 1.02 L/kg. The therapeutic concentration is from 8.2 to 24.6 mg (100 to 300 micromoles) per liter. Peak concentration following single oral doses of 7 to 50 mg/kg of body weight occurred in 1 to 2 hours. The half-life varies with dose and therefore has not been calculated.

Transformation and elimination

Hepatic; the primary metabolite is 4-carboxypyrazole (approximately 80 to 85% of an administered dose). Other metabolites include the pyrazoles 4-hydroxymethylpyrazole and the N -glucuronide conjugates of 4-carboxypyrazole and 4-hydroxymethylpyrazole.

Following multiple doses, fomepizole rapidly induces its own metabolism via the cytochrome P450 mixed-function oxidase system.

In healthy volunteers, 1 to 3.5% of an administered dose was excreted unchanged in the urine. The metabolites also are excreted unchanged in the urine.

Fomepizole is dialyzable.

See also

References

     
    This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Fomepizole". A list of authors is available in Wikipedia.
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