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Fomepizole

  • Prescription medicine
  • Prescription only
  • Identity checked
  • Sources last checked 2026-09-04

This page shows what was measured, who it was measured in, and what that does not settle.

What Fomepizole does in the body

Fomepizole injection is indicated as an antidote for ethylene glycol (such as antifreeze) or methanol poisoning, or for use in suspected ethylene glycol or methanol ingestion, either alone or in combination with hemodialysis (see DOSAGE AND ADMINISTRATION ).

From the FDA-approved label: Fomepizole is a competitive inhibitor of alcohol dehydrogenase. Alcohol dehydrogenase catalyzes the oxidation of ethanol to acetaldehyde. Alcohol dehydrogenase also catalyzes the initial steps in the metabolism of ethylene glycol and methanol to their toxic metabolites. Ethylene glycol, the main component of most antifreezes and coolants, is metabolized to glycoaldehyde, which undergoes subsequent sequential oxidations to yield glycolate, glyoxylate, and oxalate. Glycolate and oxalate are the metabolic byproducts primarily responsible for the metabolic acidosis and renal damage seen in ethylene glycol toxicosis.

Why people take it. Fomepizole injection is indicated as an antidote for ethylene glycol (such as antifreeze) or methanol poisoning, or for use in suspected ethylene glycol or methanol ingestion, either alone or in combination with hemodialysis (see DOSAGE AND ADMINISTRATION ).

What happened in people

RNAWiki has not yet published a reviewed conclusion for this use.

A fixed RNAWiki sentence

Where this came from

Wording RNAWiki always uses, not a finding about this substance.

No reviewed claim names a result for any goal on this record.

No source is stored against this line.

The limit that matters most

Not recorded.

Where it acts
Not recorded.
Kind of result
No result is published, so no kind of result applies yet
Supervision
RNAWiki has not recorded a supervision or regulatory status for this substance.

What the registries record it as

  • The substance registry classes this as chemical.

    FDA substance registry · 83LCM6L2BY · read 2026-08-29

  • Its recorded molecular formula is C4H6N2, weighing 82.1.

    US prescribing information · 911312e2-3a7c-4c97-88a8-b8d92cd12923 · read 2026-08-30

Where each sentence above came from

The use the label states, quoted from it. No plain-language version of this sentence has been written.

The use the label states, quoted from it. It is written for a clinician, not for a reader without medical training.

No statement of the main limit is recorded.

The four opening statements run to 171 words.

Words this page uses

Four words worth knowing first

Chosen from what this page shows, with each one explained before the word it depends on.

Biomarker

A biomarker is a number from a test that stands in for something about health.

A picture of it, and where the picture fails

A biomarker is like a fuel gauge.

Where that stops being true. A gauge is wired to the tank. Many biomarkers are only loosely tied to health.

What people get wrong. A better number is read as a better life. Several medicines improved a number and helped nobody.

A measurable indicator used as a substitute for a clinical outcome of interest.

Placebo

A placebo is a dummy treatment given so the real one can be compared with it.

A picture of it, and where the picture fails

A placebo is like a blank control in an experiment.

Where that stops being true. A blank does nothing. People given a placebo often do get better.

What people get wrong. A placebo effect is read as imaginary. The improvement is measured and real.

An inactive intervention matched in appearance to the test intervention, used to control for non-specific effects.

Comparator

A comparator is whatever the treatment was measured against.

A picture of it, and where the picture fails

It is like the other runner in a race.

Where that stops being true. A race has one winner. A study can show both arms improved.

What people get wrong. Results are read without asking what the other group got. Beating nothing is not beating a treatment.

The control condition against which the experimental intervention is assessed.

What happened in peopleRead from sources, not yet reviewed

What happened in people

Each card is one study: the exact question it asked, who was in it, and whether it showed what it set out to show.

Number of Participants With Adverse Events (AEs), Serious AEs, and AEs Leading to Study Discontinuation

The study did not show it

Who was studied
NCT00661141
How many people
32
Study design
Phase 2
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Result not recorded on this page
Repeated elsewhere
Unreplicated

What this does not prove. A study that did not show an effect does not show that no effect exists anywhere.

The limits of this study, and where it came from

Main limit. No limitation is recorded for this study.

How far it carries. This study is recorded from the curated record, not from the registry match.

Form and route. Injection

Interval reported. Not recorded in this summary

Written into the record, not signed off as a reviewed claim.

  • openFDA Drugs@FDA · a recorded source, not a stored snapshot
  • openFDA NDC Directory · a recorded source, not a stored snapshot
  • openFDA SPL label · a recorded source, not a stored snapshot
  • PubChem PUG-REST · a recorded source, not a stored snapshot

Difference in serum alanine transaminase (ALT) from presentation to peak recorded ALT

The study did not show it

Who was studied
NCT05517668
How many people
29
Study design
Phase 2
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Result not recorded on this page
Repeated elsewhere
Unreplicated

What this does not prove. A study that did not show an effect does not show that no effect exists anywhere.

The limits of this study, and where it came from

Main limit. No limitation is recorded for this study.

How far it carries. This study is recorded from the curated record, not from the registry match.

Form and route. Injection

Interval reported. Not recorded in this summary

Written into the record, not signed off as a reviewed claim.

  • openFDA Drugs@FDA · a recorded source, not a stored snapshot
  • openFDA NDC Directory · a recorded source, not a stored snapshot
  • openFDA SPL label · a recorded source, not a stored snapshot
  • PubChem PUG-REST · a recorded source, not a stored snapshot

Dark adaptation inhibition measured 30 minutes after drug infusion using Goldman-Weeker adaptometer.

The study did not show it

Who was studied
NCT00346853
How many people
10
Study design
Phase 1
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Result not recorded on this page
Repeated elsewhere
Unreplicated

What this does not prove. A study that did not show an effect does not show that no effect exists anywhere.

The limits of this study, and where it came from

Main limit. No limitation is recorded for this study.

How far it carries. This study is recorded from the curated record, not from the registry match.

Form and route. Injection

Interval reported. Not recorded in this summary

Written into the record, not signed off as a reviewed claim.

  • openFDA Drugs@FDA · a recorded source, not a stored snapshot
  • openFDA NDC Directory · a recorded source, not a stored snapshot
  • openFDA SPL label · a recorded source, not a stored snapshot
  • PubChem PUG-REST · a recorded source, not a stored snapshot

Oxidative metabolism of APAP

The study did not show it

Who was studied
NCT03878693
How many people
6
Study design
Early phase 1
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Result not recorded on this page
Repeated elsewhere
Unreplicated

What this does not prove. A study that did not show an effect does not show that no effect exists anywhere.

The limits of this study, and where it came from

Main limit. No limitation is recorded for this study.

How far it carries. This study is recorded from the curated record, not from the registry match.

Form and route. Injection

Interval reported. Not recorded in this summary

Written into the record, not signed off as a reviewed claim.

  • openFDA Drugs@FDA · a recorded source, not a stored snapshot
  • openFDA NDC Directory · a recorded source, not a stored snapshot
  • openFDA SPL label · a recorded source, not a stored snapshot
  • PubChem PUG-REST · a recorded source, not a stored snapshot
What we know
RNAWiki holds 4 written-up human studies for this substance, each with the question it asked.
How we know it
Each card names the study, the number of people and what the study set out to measure.
What this does not prove
These summaries were written by a person and have not been signed off as reviewed claims.
Why it matters
A study that failed is as informative as one that worked, and both are here.
What we still do not know
No reviewed claim exists, so no exact population, effect size or interval is published yet.

What is missing or unclearRead from sources, not yet reviewed

Were people like you studied?

RNAWiki cannot tell whether a study fits you. It can show who was in it, and where the result stops carrying.

Who was studied

People similar to this profile were included.

  • & USAGE Fomepizole is indicated as an antidote for ethylene glycol (such as antifreeze) or methanol poisoning, or for use in suspected ethylene glycol or methanol ingestion, either alone or in combination with hemodialysis (see DOSAGE AND ADMINISTRATION ).

Who is missing from the studies

  • Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.

What the label states about particular groups

  • On pediatric, the label states: “Safety and effectiveness in pediatric patients have not been established.”

    US prescribing information · 911312e2-3a7c-4c97-88a8-b8d92cd12923 · read 2026-08-30

  • On older people, the label states: “Safety and effectiveness in geriatric patients have not been established.”

    US prescribing information · 911312e2-3a7c-4c97-88a8-b8d92cd12923 · read 2026-08-30

  • On people who are pregnant, the label states: “Animal reproduction studies have not been conducted with fomepizole.”

    US prescribing information · 911312e2-3a7c-4c97-88a8-b8d92cd12923 · read 2026-08-30

  • On people who are breastfeeding, the label states: “It is not known whether fomepizole is excreted in human milk.”

    US prescribing information · 911312e2-3a7c-4c97-88a8-b8d92cd12923 · read 2026-08-30

Where the result stopped carrying

  • This is a scope explorer, not a diagnosis engine.
  • It shows who was studied so you can see whether people similar to you were included.

RNAWiki cannot tell whether a study fits you. It can show who was in it.

What it would be like to takeRead from sources, not yet reviewed

Why it might seem to do nothing

A real effect and a noticed effect are different things. These are the recorded reasons the two come apart.

It was studied in different people

The people in the studies were not much like the reader.

On this record: Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.

The evidence may simply be wrong

Small early studies often do not hold up.

On this record: RNAWiki has not yet published a reviewed conclusion for this use.

Other reasons RNAWiki checked and found nothing for (11)
It was studied for a different goal
The studies measured something else entirely. Nothing in this record points to this reason.
A different form was studied
The studied form is not the form on the shelf. Nothing in this record points to this reason.
There was nothing to correct
Where a level is already normal, topping it up may change nothing. Nothing in this record points to this reason.
Something else had to happen too
In the studies it was paired with training, a diet or another treatment. Nothing in this record points to this reason.
The change is too small to feel
A real change can still sit below what a person notices. Nothing in this record points to this reason.
Day-to-day swing hides it
Sleep, food, stress and time of day move most numbers more than this would. Nothing in this record points to this reason.
Not enough time yet
The studies ran longer than the person has waited. Nothing in this record points to this reason.
It was not taken as studied
Missed days change the result, and studies count them. Nothing in this record points to this reason.
Something else changed at the same time
Two changes at once cannot be told apart afterwards. Nothing in this record points to this reason.
The product may not be what it says
Contents of a sold product are not always what the label states. Nothing in this record points to this reason.
No recorded reason
RNAWiki has nothing stored that would explain it. Nothing in this record points to this reason.

None of these is a reason to take more. Taking more is not a step this page ever suggests.

What it would be like to takeRead from sources, not yet reviewed

What taking it involves

The recorded facts about getting hold of it and using it. Nothing here is a suggestion about what you should do.

How it is supplied

Prescription only

Quoted from a source

Where this came from

Copied from a source RNAWiki stored, with the source named.

Read from the recorded approval status.

No source is stored against this line.

Form and route

Injection

Source-linked record

Where this came from

A person wrote this into the record with the study named beside it. No reviewer has signed it off.

The form and route recorded on this substance.

No source is stored against this line.

Who oversees it

RNAWiki has not recorded a supervision or regulatory status for this substance.

Quoted from a source

Where this came from

Copied from a source RNAWiki stored, with the source named.

No register row and no identity class settled the question.

No source is stored against this line.

What is in the pack

Sold as injectable, injection, solution, injection, given by the injection, intravenous route.

Source-linked record

Where this came from

A person wrote this into the record with the study named beside it. No reviewer has signed it off.

Recorded notes on how this is sold and what that means for what is in the pack.

No source is stored against this line.

Where it is registered

Regulatory records are listed in the technical disclosure at the foot of this page.

Counted from records

Where this came from

A count of rows RNAWiki holds. It describes our records, not your body.

Register entries are stored per jurisdiction and shown with their dates.

No source is stored against this line.

Why people stop

Not recorded.

Nothing recorded

Where this came from

RNAWiki holds nothing here and says so rather than guessing.

No record of why people stopped taking it is stored for this substance.

No source is stored against this line.

What it would be like to takeNothing found in the sources checked

What can go wrong

Sorted by where each line came from. A regulator's label and a report somebody sent in are not the same kind of fact.

Nothing found in the sources checked

No harm is recorded against this substance in the sources RNAWiki checked. Finding nothing is not the same as showing there is nothing.

The sources listed were searched and held nothing. That is not the same as nothing existing.

Over a long time. No completed tested study window is recorded, so long-term effects are not established by the registry record.

Groups the studies covered thinly. Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.

What is missing or unclearRead from sources, not yet reviewed

Does the exact form matter?

Evidence belongs to the exact thing that was tested. A different salt, a different mixture or a different preparation is a different question.

The form that was studied

Injection

Source-linked record

Where this came from

A person wrote this into the record with the study named beside it. No reviewer has signed it off.

The form used in the studies cited on this page.

No source is stored against this line.

What is sold

Not recorded.

Nothing recorded

Where this came from

RNAWiki holds nothing here and says so rather than guessing.

Nothing further is recorded about which forms are sold.

No source is stored against this line.

What is recorded as being sold

  • 13 products list this as an active ingredient in the United States drug directory. 13 of them contain it and nothing else.

    FDA National Drug Code directory · 76339-106 · read 2026-08-29

  • They are sold as injection, injection, solution, liquid and powder, taken intravenous.

    FDA National Drug Code directory · 76339-106 · read 2026-08-29

  • The regulator's established pharmacologic class for it is antidote [epc].

    FDA National Drug Code directory · 76339-106 · read 2026-08-29

  • 7 published labels name it as an active ingredient. 7 of them describe this substance alone, which is where its own label text on this page comes from.

    US prescribing information · 82dc2920-af7f-4e43-9f6d-8877a71884cd · read 2026-08-29

  • Those labels are classed as human prescription drug.

    US prescribing information · 82dc2920-af7f-4e43-9f6d-8877a71884cd · read 2026-08-29

  • Fomepizole is intravenous at HOW SUPPLIED Fomepizole Injection is supplied as a sterile, preservative-free solution for intravenous use as: NDC 67457-211-02 carton containing one single-dose vial which contains 1.5 mL (1 g/mL) of fomepizole Store a…, recorded as fda label in effect 2021-04-15 in the United States.

    US prescribing information · 911312e2-3a7c-4c97-88a8-b8d92cd12923 · read 2026-08-30

Evidence carries across two names for one substance. It does not carry across a salt, a mirror form or a mixture.

What it would be like to takeRead from sources, not yet reviewed

What you could measure

This one is decided with a clinician, so this section holds questions to ask rather than a plan to run.

RNAWiki could not confidently classify this substance, so no self-experiment plan is offered.

Questions worth asking

  • Which of the trials of Fomepizole studied people like me?
  • What was measured, and for how long?
  • Was the result a laboratory value or a health outcome?
  • What would we watch for, and when would we stop?

Tracking can show whether something changed for you. It cannot show what caused it.

RNAWiki records evidence. It does not say whether this substance is right for you.

What is missing or unclearRead from sources, not yet reviewed

What nobody knows yet

Open questions, each with why it is open and what would close it.

Missing populations

Which groups were under-represented in the studies has not been recorded.

Why it matters. Recorded by the evidence model as a gap on this record.

What would answer it

A study that measures it, and a reviewer to sign it off.

Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.

Missing long-term data

No completed tested study window is recorded.

Why it matters. Recorded by the evidence model as a gap on this record.

What would answer it

A study that measures it, and a reviewer to sign it off.

Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.

No reviewed conclusion

RNAWiki has not yet published a reviewed conclusion for this use.

Why it matters. Recorded by the evidence model as a gap on this record.

What would answer it

A study that measures it, and a reviewer to sign it off.

Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.

Missing interaction studies

No interaction was found in the registers checked. Not finding one is not the same as showing there is none.

Why it matters. Recorded by the evidence model as a gap on this record.

What would answer it

A study that measures it, and a reviewer to sign it off.

Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.

Formulation uncertainty

Several salts, forms or products of Fomepizole are recorded. Results from one form may not transfer to another.

Why it matters. Recorded by the evidence model as a gap on this record.

What would answer it

A study that measures it, and a reviewer to sign it off.

Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.

Mechanism not reviewed

No reviewed mechanism story exists for this substance.

Why it matters. Recorded by the evidence model as a gap on this record.

What would answer it

A study that measures it, and a reviewer to sign it off.

Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.

What happened in peopleRead from sources, not yet reviewed

Check any of this yourself

Every line above traced back to the study it came from. This is the technical layer, and the vocabulary changes here.

How many documents were read

  • 7 documents were read for this substance.

    RNAWiki source record

  • 7 of them state the same volumeOfDistribution, and they agree.

    RNAWiki source record

Where else this substance is registered

FDA substance identifier (UNII)
83LCM6L2BY
RxNorm concept
310414

Checks this page had to pass

  • Passed

    Identity resolved

    no open identity hold

  • Passed

    No unresolved merge across substance families

    no quarantine open

  • Passed

    Every public sentence names a source

    The opening statement carries the origin: Quoted from a stored source.

  • Not passed

    Trial roles classified for highlighted evidence

    No registered study is classified as testing this substance.

  • Passed

    No internal keys in reader text

    enforced by the copy-contract test over the rendered page

  • Not passed

    Safety mode resolved

    No register row and no identity class settled the question.

  • Passed

    Canonical metadata present

    slug and display name present

What is missing or unclearRead from sources, not yet reviewed

How this medicine reached us

Kept near the foot of the page. A historical event moves up only when it changes something about this substance today.

What the approval register records

  • 6 approved applications cover products containing this substance. The earliest was NDA020696, approved 19971204 to PAR PHARM INC.

    Drugs@FDA application register · NDA020696 · read 2026-08-29

  • Marketing status on the register: discontinued and prescription.

    Drugs@FDA application register · NDA020696 · read 2026-08-29

  • The earliest marketing start date recorded for a listed product is 20050627.

    FDA National Drug Code directory · 76339-106 · read 2026-08-29

What is missing or unclearRead from sources, not yet reviewed

What to learn next

Ordered by what would most change how you read this page, starting with what is easiest to misunderstand.

This order is fixed in code and does not count clicks or time on the page.

What is not here

9 questions this page could not answer

These sections were prepared and left out because there was nothing to put in them. They are listed rather than hidden, so the gaps in this record are visible.

  • What was measured, goal by goal — found nothing in the sources checked.
  • How close this is to real life — found nothing in the sources checked.
  • The path through the body — found nothing in the sources checked.
  • Felt, measured, or meaningful — found nothing in the sources checked.
  • How long anything takes — found nothing in the sources checked.
  • What it may clash with — found nothing in the sources checked.
  • Other ways to the same goal — found nothing in the sources checked.
  • Claims that go past the evidence — found nothing in the sources checked.
  • What changed on this page — found nothing in the sources checked.

The record as stored

The full record, for auditing

Everything above is built from what is below. This layer keeps the technical vocabulary, record identifiers and every stored row, so a reader who wants to check the page can.

Recorded evidence blocks (7)

On the Fomepizole label: indicated for what?

"Fomepizole injection is indicated as an antidote for ethylene glycol (such as antifreeze) or methanol poisoning, or for use in suspected ethylene glycol or methanol ingestion, either alone or in combination with hemodialysis (see DOSAGE AND ADMINISTRATION ).": indications and usage on Fomepizole's label. DailyMed label · 1dea37fd-ec17-416e-b28e-980a87d49e1a · 2023-10-26

3 registered trials of Fomepizole — at which phases?

Registered studies posting no result
1 of 3

3 registered studies of Fomepizole: 1 early phase1, 1 na or unstated, 1 phase2. CLINICALTRIALS_SNAPSHOT · 2026-09-01

11 with a PubMed record

Show the evidence
  • early phase1
    1
  • na or unstated
    1
  • phase2
    1
  • completed
    3

recorded 2026-09-01 · last checked 2026-09-04

Human studies of Fomepizole used Fomepizole Intravenous Infusion 1.5 g — over how long?

Human studies of Fomepizole used "Fomepizole Intravenous Infusion 1.5 g". ClinicalTrials.gov · 2026-09-01

Show the evidence
  • human NCT02415712
    Fomepizole Intravenous Infusion 1.5 g

recorded 2026-09-01 · last checked 2026-09-04

Which one trial of Fomepizole posted no result?

Posted no result
1 of 1 completed trials
Registrations
NCT03878693
Completion dates
oldest 2018-10-31
Show the evidence
  • Trial NCT03878693
    2018-10-31

At the median, Fomepizole's trials enrolled 32 people — anything larger?

Median enrolment
32
Largest enrolment
147
Registered trials counted
3

What do 4 spontaneous reports say about Fomepizole — and not say?

These are reports people sent to a regulator. They do not show the medicine caused the reaction. Nobody counted how many people took the medicine and reported nothing. The same event can be reported more than once, and many reports are incomplete. News coverage, lawsuits and new warnings change how often people report. A count is not a rate and not a risk.

Fomepizole appears in spontaneous reports to regulators. Across the 1 most-reported reaction term, 4 reaction mentions were counted: liver injury 4. FAERS via Open Targets · CHEMBL1308 · 2026-06-24

Show the evidence
  • liver injury
    4

recorded 2026-06-24 · last checked 2026-09-04

Which reaction does Fomepizole's label not list?

liver injury reported for Fomepizole, absent from its label. FAERS via Open Targets · CHEMBL1308 · 2026-06-24

2 label terms; 1 reported and unlisted; 1dea37fd-ec17-416e-b28e-980a87d49e1a

Show the evidence
  • liver injury
    count not stated

recorded 2026-06-24 · last checked 2026-09-04

Where it is registered
Identifiers, relations and other names

The exact record

ChEMBL id
CHEMBL1308
PubChem CID
3406
CAS number
7554-65-6
RxCUI
15226
InChIKey
RIKMMFOAQPJVMX-UHFFFAOYSA-N
Also called
4-methylpyrazole, Fomepizol, FOMEPIZOLE [GREEN BOOK], FOMEPIZOLE [JAN], FOMEPIZOLE [MART.], FOMEPIZOLE [MI], FOMEPIZOLE [ORANGE BOOK], FOMEPIZOLE [USAN], FOMEPIZOLE [VANDF], Fomepizole [WHO-DD]
Development code
4-MP, NSC-760365
Trade name
Antizol
Sources (6)

Sources

ChEMBL 37 — CC BY-SA 3.0 Unported · ChEMBL ATC CC BY-SA · ClinicalTrials.gov — US Government work · Open Targets 26.06 — CC0 · mixed register set; per-register licences in docs/specs/corpus-20k-sources.md · openFDA / DailyMed — US Government work

How these records are assembled · Which registers were checked

Index-quality checks
  • identity passed: no open identity hold
  • required summary fields resolved: 4 required field(s) not terminal: Why people use it, Best-supported result, Biggest unanswered question, Human evidence
  • public claims reviewed: 0 reviewed claim(s); drafts are never rendered
  • source coverage passed: 6 source rows
  • no critical contamination: no quarantine open
  • canonical metadata passed: slug and display name present
  • no raw internal fields: enforced by the copy-contract test over the rendered page

This is a record of evidence. It is not medical advice, and it does not say this substance suits you. Nothing here says any substance on RNAWiki is appropriate for a child.