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Zafirlukast

  • 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 Zafirlukast does in the body

The prophylaxis and chronic treatment of asthma

From the FDA-approved label: Zafirlukast is a selective and competitive receptor antagonist of leukotriene D 4 and E 4 (LTD 4 and LTE 4 ), components of slow-reacting substance of anaphylaxis (SRSA). Cysteinyl leukotriene production and receptor occupation have been correlated with the pathophysiology of asthma, including airway edema, smooth muscle constriction, and altered cellular activity associated with the inflammatory process, which contribute to the signs and symptoms of asthma. Patients with asthma were found in one study to be 25 to 100 times more sensitive to the bronchoconstricting activity of inhaled LTD 4 than nonasthmatic subjects.

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 · XZ629S5L50 · read 2026-08-29

Where each sentence above came from

No recorded sentence describes the change this makes in a way that stands on its own. The page opens with what it is taken for instead, and the recorded explanation follows below.

Shown as the opening line on this page.

No statement of the main limit is recorded.

The four opening statements run to 116 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.

Percentage of Participants Not Experiencing a Protocol-defined Severe Exacerbation During the Study

The study did not show it

Who was studied
NCT01125748
How many people
176
Study design
Phase 4
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. Oral

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

Time to clinical improvement,

The study did not show it

Who was studied
NCT04871828
How many people
66
Study design
Phase 3
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. Oral

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

Bioequivalence on Cmax and AUC parameters

The study did not show it

Who was studied
NCT01283061
How many people
44
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. Oral

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

Total Nasal Symptom Score (TNSS)

The study did not show it

Who was studied
NCT06069063
How many people
12
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. Oral

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

CA-125 Response Rate

The study did not show it

Who was studied
NCT04339140
How many people
5
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. Oral

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

Capsular Thickness

The study did not show it

Who was studied
NCT02950480
How many people
4
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. Oral

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 6 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.

  • Zafirlukast tablets are indicated for the prophylaxis and chronic treatment of asthma in adults and children 5 years of age and older.

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: “The safety and effectiveness of zafirlukast for pediatric patients less than 5 years of age has not been established.”

    US prescribing information · 6ccb96af-2647-9206-5eee-49a825d32488 · read 2026-08-30

  • On older people, the label states: “Based on cross-study comparison, the clearance of zafirlukast is reduced in patients 65 years of age and older such that C max and AUC are approximately 2- to 3-fold greater than those of younger patients (see DOSAGE AND ADMINISTRATION and CLINICAL PHARMACOLOGY ).”

    US prescribing information · 6ccb96af-2647-9206-5eee-49a825d32488 · read 2026-08-30

  • On people who are pregnant, the label states: “At an oral dose of 2000 mg/kg/day in rats, maternal toxicity and deaths were seen with increased incidence of early fetal resorption.”

    US prescribing information · 6ccb96af-2647-9206-5eee-49a825d32488 · read 2026-08-30

  • On people who are breastfeeding, the label states: “Following repeated 40 mg twice-a-day dosing in healthy women, average steady-state concentrations of zafirlukast in breast milk were 50 ng/mL compared to 255 ng/mL in plasma.”

    US prescribing information · 6ccb96af-2647-9206-5eee-49a825d32488 · 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

Oral

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 tablet, tablet, film coated, tablet, coated, given by the oral 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

Oral

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

  • 20 products list this as an active ingredient in the United States drug directory. 20 of them contain it and nothing else.

    FDA National Drug Code directory · 59651-291 · read 2026-08-29

  • They are sold as powder, tablet, coated and tablet, film coated, taken oral.

    FDA National Drug Code directory · 59651-291 · read 2026-08-29

  • The regulator's established pharmacologic class for it is cytochrome p450 2c9 inhibitors [moa], leukotriene receptor antagonist [epc] and leukotriene receptor antagonists [moa].

    FDA National Drug Code directory · 59651-291 · 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 · d2256673-fe8b-4fba-a73a-a81e24e47cf8 · read 2026-08-29

  • Those labels are classed as human prescription drug.

    US prescribing information · d2256673-fe8b-4fba-a73a-a81e24e47cf8 · read 2026-08-29

  • Zafirlukast is oral at HOW SUPPLIED Zafirlukast tablets 10 mg are white to light pink, round, film coated tablets debossed with ‘R’ on one side and ‘625’ on other side and are supplied in bottles of 30, 60, 100, 500 and unit dose blister pack…, recorded as fda label in effect 2018-11-16 in the United States.

    US prescribing information · 6ccb96af-2647-9206-5eee-49a825d32488 · read 2026-08-30

  • Recorded price in US: 0.52946–0.64362 USD per one unit as the pricing file counts it — a tablet, capsule, patch or single item, across 10 priced products whose strengths and pack forms differ, as of 2026-08-26, paid by retail pharmacies buying the product, as surveyed by the Centers for Medicare & Medicaid Services. It is not a list price, an insurance price, or what anyone pays at a counter..

    Recorded source · 2026-08-26 · read 2026-08-28

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 Zafirlukast 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 Zafirlukast 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 halfLife, and they agree.

    RNAWiki source record

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

    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)
XZ629S5L50
RxNorm concept
199655

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: Written into the record, not signed off.

  • 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

  • 5 approved applications cover products containing this substance. The earliest was NDA020547, approved 19960926 to STRIDES PHARMA INTL.

    Drugs@FDA application register · NDA020547 · read 2026-08-29

  • Marketing status on the register: prescription.

    Drugs@FDA application register · NDA020547 · read 2026-08-29

  • The earliest marketing start date recorded for a listed product is 19990917.

    FDA National Drug Code directory · 59651-291 · 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 (10)

On the Zafirlukast label: indicated for what?


"Zafirlukast tablets are indicated for the prophylaxis and chronic treatment of asthma in adults and children 5 years of age and older.": indications and usage on Zafirlukast's label. DailyMed label · a60f39f6-d590-4b00-8751-7f12b7ec5385 · 2024-10-11

4 registered trials of Zafirlukast — at which phases?


Registered studies posting no result
2 of 4

4 registered studies of Zafirlukast: 3 phase2, 1 phase1. CLINICALTRIALS_SNAPSHOT · 2026-09-01

87 with a PubMed record

Show the evidence
  • phase2
    3
  • phase1
    1
  • completed
    2
  • not yet recruiting
    1
  • terminated
    1

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

Why did Zafirlukast's trial NCT02950480 stop?


1 recorded trial of Zafirlukast stopped. CLINICALTRIALS_SNAPSHOT · 2026-09-01

"Low accrual."; 1 of 4 registered studies

Show the evidence
  • Trial NCT02950480
    terminated; "Low accrual."

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

Human studies of Zafirlukast used Accolate tablets 20 mg — over how long?


Human studies of Zafirlukast used "Accolate tablets 20 mg". ClinicalTrials.gov · 2026-09-01

Show the evidence
  • human NCT01283061
    Accolate tablets 20 mg

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

Zafirlukast's half-life is 10 hours — which schedules were studied?


10 hours, the half-life Zafirlukast's label states: "In the pivotal bioequivalence study, the mean terminal half-life of zafirlukast is approximately 10 hours in both normal adult subjects and patients with asthma." DailyMed label · a60f39f6-d590-4b00-8751-7f12b7ec5385 · 2024-10-11

tmax 3 hours; bioavailability 40 %.

Show the evidence
  • half life clinical_pharmacology
    10 hours; In the pivotal bioequivalence study, the mean terminal half-life of zafirlukast is approximately 10 hours in both normal adult subjects and patients with asthma.
  • tmax clinical_pharmacology
    3 hours; Peak plasma concentrations are generally achieved 3 hours after oral administration.
  • bioavailability clinical_pharmacology
    40 %; In two separate studies, one using a high fat and the other a high protein meal, administration of zafirlukast with food reduced the mean bioavailability by approximately 40%.
  • metabolism clinical_pharmacology
    Metabolism Zafirlukast is extensively metabolized.

recorded 2024-10-11 · last checked 2026-09-04

Which one trial of Zafirlukast posted no result?


Posted no result
1 of 1 completed trials
Registrations
NCT01283061
Completion dates
oldest 2008-01
Show the evidence
  • Trial NCT01283061
    2008-01

At the median, Zafirlukast's trials enrolled 8.5 people — anything larger?


Median enrolment
8.5
Largest enrolment
44
Registered trials counted
4

What do 46 spontaneous reports say about Zafirlukast — 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.

Zafirlukast appears in spontaneous reports to regulators. Across the 10 most-reported reaction terms, 46 reaction mentions were counted: asthma 15; allergic granulomatous angiitis 6; jaundice 5; hepatic function abnormal 4. FAERS via Open Targets · CHEMBL603 · 2026-06-24

Show the evidence
  • asthma
    15
  • allergic granulomatous angiitis
    6
  • jaundice
    5
  • hepatic function abnormal
    4
  • hepatitis
    4
  • blood count abnormal
    3
4 more recorded rows
  • anorexia
    3
  • ocular icterus
    2
  • dyspnoea at rest
    2
  • mononeuritis
    2

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

Which 10 reactions does Zafirlukast's label not list?


allergic granulomatous angiitis, anorexia and asthma and 7 more reported for Zafirlukast, absent from its label. FAERS via Open Targets · CHEMBL603 · 2026-06-24

3 label terms; 10 reported and unlisted; a60f39f6-d590-4b00-8751-7f12b7ec5385

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  • allergic granulomatous angiitis
    count not stated
  • anorexia
    count not stated
  • asthma
    count not stated
  • blood count abnormal
    count not stated
  • dyspnoea at rest
    count not stated
  • hepatic function abnormal
    count not stated
4 more recorded rows
  • hepatitis
    count not stated
  • jaundice
    count not stated
  • mononeuritis
    count not stated
  • ocular icterus
    count not stated

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

Zafirlukast and CYP2C9, CYP3A4 and CYTOCHROME P450: shared by which compounds?


CYP2C9, CYP3A4 and CYTOCHROME P450 appear in Zafirlukast's recorded interaction sentences, 8 in all. DailyMed label · a60f39f6-d590-4b00-8751-7f12b7ec5385 · 2024-10-11

CYP2C9, CYP2C9, CYP3A4, CYP3A4; 4 shared nodes; drug_interactions, clinical_pharmacology

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Interaction statement

  • drug_interactions
    This interaction is probably due to an inhibition by zafirlukast of the cytochrome P450 2C9 isoenzyme system.
  • drug_interactions
    No formal drug-drug interaction studies with zafirlukast and other drugs known to be metabolized by the cytochrome P450 2C9 isoenzyme (eg, tolbutamide, phenytoin, carbamazepine) have been conducted; however, care should be exercised when zafirlukast is coadministered with these drugs.
  • drug_interactions
    Coadministration of zafirlukast with fluconazole, a moderate CYP2C9 inhibitor, resulted in increased plasma levels of zafirlukast, by approximately 58% (90% CI:28, 95).
  • drug_interactions
    Zafirlukast exposure is likely to be increased by other moderate and strong CYP2C9 inhibitors.
  • drug_interactions
    Coadministration of zafirlukast with itraconazole, a strong CYP3A4 inhibitor, caused no change in plasma levels of zafirlukast.
  • drug_interactions
    No other formal drug-drug interaction studies between zafirlukast and marketed drugs known to be metabolized by the P450 3A4 (CYP3A4) isoenzyme (eg, dihydropyridine calcium-channel blockers, cyclosporin, cisapride) have been conducted.
2 more recorded rows
  • Interaction statement drug_interactions
    As zafirlukast is known to be an inhibitor of CYP3A4 in vitro , it is reasonable to employ appropriate clinical monitoring when these drugs are coadministered with zafirlukast.
  • Interaction statement clinical_pharmacology
    In vitro studies using human liver microsomes showed that the hydroxylated metabolites of zafirlukast excreted in the feces are formed through the cytochrome P450 2C9 (CYP2C9) pathway.

CYP2C9

  • FINGOLIMOD LAURYL SULFATE, FOSAPREPITANT DIMEGLUMINE, TAFAMIDIS MEGLUMINE, Arimoclomol, Rasagiline, Golodirsen, Tinidazole, Naldemedine
  • FINGOLIMOD LAURYL SULFATE, FOSAPREPITANT DIMEGLUMINE, TAFAMIDIS MEGLUMINE, Arimoclomol, Rasagiline, Golodirsen, Tinidazole, Naldemedine

CYP3A4

  • FINGOLIMOD LAURYL SULFATE, ERYTHROMYCIN LACTOBIONATE, FOSAPREPITANT DIMEGLUMINE, TAFAMIDIS MEGLUMINE, Arimoclomol, Beclometasone, Rasagiline, Sofpironium
  • FINGOLIMOD LAURYL SULFATE, ERYTHROMYCIN LACTOBIONATE, FOSAPREPITANT DIMEGLUMINE, TAFAMIDIS MEGLUMINE, Arimoclomol, Beclometasone, Rasagiline, Sofpironium

recorded 2024-10-11 · last checked 2026-09-04

Where it is registered
Identifiers, relations and other names

The exact record

ChEMBL id
CHEMBL603
PubChem CID
5717
CAS number
107753-78-6
RxCUI
114970
InChIKey
YEEZWCHGZNKEEK-UHFFFAOYSA-N
Trade name
Accolate
Development code
ICI 204,219, ICI-204219
Also called
CARBAMIC ACID, (3-((2-METHOXY-4-(((2-METHYLPHENYL)SULFONYL)AMINO)CARBONYL)PHENYL)METHYL)-1-METHYL-1H-INDOL-5-YL)-, CYCLOPENTYL ESTER, Cyclopentyl 3-[2-methoxy-4-[(O-tolylsulfonyl)carbamoyl]benzyl]-1-methylindole-5-carbamate, ZAFIRLUKAST [JAN], ZAFIRLUKAST [MART.], ZAFIRLUKAST [MI], ZAFIRLUKAST [ORANGE BOOK], ZAFIRLUKAST [USAN]
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

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