This page shows what was measured, who it was measured in, and what that does not settle.
What Warfarin does in the body
Warfarin blocks the recycling enzyme, so the liver runs short and starts releasing clotting factors that do not work.
Your liver builds clotting factors that only become functional after a finishing step requiring vitamin K, and the vitamin has to be recycled after each use. It takes days for the existing working factors to wash out, which is why the drug is slow to start and slow to stop.
Why people take it. Preventing and treating blood clots, including stroke from an irregular heartbeat and clots on a mechanical heart valve
What happened in people
A 64% reduction in stroke against control across 6 randomised trials in atrial fibrillation, and 39% better than antiplatelet therapy across 12 trials
✎ 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 recorded finding that sits closest to something a person would notice. Written into the record, not signed off, and it carries no population or interval.
Still on the WHO Model List of Essential Medicines, and the only anticoagulant licensed for mechanical heart valves
Where it acts
Hepatocyte endoplasmic reticulum (liver)
Kind of result
Living longer, or avoiding a major event
Supervision
Professional supervision is normally required. A regulator classifies this substance in a way that restricts how it is supplied.
What the registries record it as
Its recorded molecular formula is C19H15NaO4.
US prescribing information · bd6ea120-5d1c-4815-94f2-81e28dc6b7a9 · read 2026-08-30
Where each sentence above came from
A person wrote this explanation into the record, with the studies named in the path below.
The recorded use, written for a reader without medical training. Not signed off.
A limit recorded against this substance. Not signed off as a reviewed claim.
The four opening statements run to 110 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.
Stand-in result
A stand-in result is a number measured because the real result takes too long.
A picture of it, and where the picture fails
It is like judging a journey by the speedometer rather than by arriving.
Where that stops being true. Speed does predict arrival. Many stand-in results do not predict the real one.
What people get wrong. A stand-in result is often reported as the result itself.
A surrogate endpoint substituted for a clinical endpoint, valid only where the substitution has been shown to hold.
Randomisation
Randomisation means chance decides who gets which treatment.
A picture of it, and where the picture fails
It is like a coin toss deciding the groups.
Where that stops being true. A coin toss is fair once. Fairness here comes from doing it for everyone.
What people get wrong. It is thought to make groups identical. It makes them similar on average, including on things nobody measured.
Allocation of participants to arms by a chance process, so that unmeasured factors are balanced in expectation.
Confidence interval
A confidence interval is the range the true answer is likely to sit in.
A picture of it, and where the picture fails
It is like a weather forecast giving a range rather than one number.
Where that stops being true. A forecast range covers tomorrow. This one covers what the study could resolve.
What people get wrong. The middle number is read as the answer. A range crossing zero means no change is still possible.
An interval estimate that would contain the true parameter in a stated proportion of repeated studies.
Pathway
A pathway is a chain of steps inside a cell, each one setting off the next.
A picture of it, and where the picture fails
A pathway is like a row of dominoes.
Where that stops being true. Dominoes fall one way. Pathways loop back and can switch themselves off.
What people get wrong. Changing one step is read as changing the outcome. Other steps often absorb it.
An ordered series of molecular interactions producing a defined cellular change.
What happened in people◇Read from sources, not yet reviewed
What was measured, goal by goal
One row for each goal a registered study measured something for. One column for each kind of thing that could be measured.
Registered studies list 40 outcome measures that RNAWiki could read. A registered study says what someone planned to measure. It does not say what they found. 0 of the matched studies tested this substance, and 0 posted a result.
There is no single score. A strong test result and a weak life result are different facts.
Goals down the side, kinds of measurement across the top. Each cell says what kind of thing was registered, not what was found.
Goal
Life outcome
What a body can do
How a person feels
A test result
A step in the body
Harms
How long
Who was studied
Mood
∅Nothing in the sources checkedNo registered study lists a life outcome for this goal.
∅Nothing in the sources checkedNo registered study lists a performance measure for this goal.
…Waiting for a reviewer1 registered symptom measure.
∅Nothing in the sources checkedNo registered study lists a test result for this goal.
∅Nothing in the sources checkedNo registered study lists a body-step measure for this goal.
—Not recordedHarms were not a registered measure for this goal.
—Not recordedNo finished study window is recorded.
…Waiting for a reviewerWho was studied is listed further down the page.
Body weight
∅Nothing in the sources checkedNo registered study lists a life outcome for this goal.
∅Nothing in the sources checkedNo registered study lists a performance measure for this goal.
∅Nothing in the sources checkedNo registered study lists a symptom measure for this goal.
△Only a number moved1 registered test measure.
∅Nothing in the sources checkedNo registered study lists a body-step measure for this goal.
—Not recordedHarms were not a registered measure for this goal.
—Not recordedNo finished study window is recorded.
…Waiting for a reviewerWho was studied is listed further down the page.
Which registered measures put each goal on this table
Mood
anxiety
Body weight
body weight from baseline to 48 weeks
Sorted by fixed word lists, version v1. A name the rules do not recognise stays unsorted rather than moving to the nearest column.
What each mark on this table means
∅ Nothing in the sources checked
No registered study lists a life outcome for this goal.
… Waiting for a reviewer
1 registered symptom measure.
— Not recorded
Harms were not a registered measure for this goal.
△ Only a number moved
1 registered test measure.
What happened in people◇Read 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 time in the therapeutic INR range from day 4 or 5 through day 28, genotype-guided versus clinically guided
✗ The study did not show it
Who was studied
COAG (NCT00839657)
How many people
1015
Study design
Randomised blinded trial of dosing strategy, 4 weeks
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
45.2% against 45.4%; adjusted mean difference -0.2 (95% CI -3.4 to 3.1), P = 0.91
Repeated elsewhere
Failed to Replicate
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. A significant interaction with race (p=0.003): among Black patients, time in therapeutic range was lower in the genotype-guided group.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet in nine strengths, colour-coded by strength, plus an intravenous formulation
Interval reported. 95% CI -3
Written into the record, not signed off as a reviewed claim.
Percentage of time in the therapeutic INR range of 2.0 to 3.0 during the first 12 weeks
✓ The study showed what it set out to show
Who was studied
EU-PACT warfarin trial (NCT01119300)
How many people
455
Study design
Multicentre randomised controlled trial, 12 weeks
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
67.4% against 60.3%; adjusted difference 7.0 points (95% CI 3.3 to 10.6)
Repeated elsewhere
Partially Replicated
What this does not prove. Meeting one endpoint in one population does not carry to other goals or other people.
The limits of this study, and where it came from
Main limit. The control group received a fixed 3-day loading regimen, not a clinical algorithm. The comparator, not the genotype, is what separates this result from COAG.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet in nine strengths, colour-coded by strength, plus an intravenous formulation
Interval reported. 95% CI 3
Written into the record, not signed off as a reviewed claim.
Composite of major bleeding, INR of 4 or greater, venous thromboembolism or death
✓ The study showed what it set out to show
Who was studied
GIFT (NCT01006733)
How many people
1650
Study design
Randomised 2-by-2 factorial trial in elective arthroplasty
Compared against
Not recorded for this study
Kind of result
Living longer, or avoiding a major event
What was found
10.8% against 14.7%; absolute difference 3.9 points (95% CI 0.7-7.2), P = 0.02
Repeated elsewhere
Unreplicated
What this does not prove. Meeting one endpoint in one population does not carry to other goals or other people.
The limits of this study, and where it came from
Main limit. The composite was driven by the INR component (56 against 77 events); major bleeding was 2 against 8 with an interval spanning 0.05 to 1.15, and there were no deaths. The population was 91.0% white.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet in nine strengths, colour-coded by strength, plus an intravenous formulation
Interval reported. 95% CI 0
Written into the record, not signed off as a reviewed claim.
Ischaemic or haemorrhagic stroke or systemic embolism
✗ The study did not show it
Who was studied
ARISTOTLE (apixaban versus warfarin, NCT00412984)
How many people
18201
Study design
Randomised double-blind active-controlled trial, median 1.8 years
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Warfarin 1.60% per year against apixaban 1.27%; HR 0.79 (95% CI 0.66-0.95), P = 0.01 for superiority of apixaban
Repeated elsewhere
Replicated
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. Ischaemic or uncertain-type stroke did not differ significantly (HR 0.92, p=0.42). The advantage came from haemorrhagic stroke, 0.24% against 0.47% per year.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet in nine strengths, colour-coded by strength, plus an intravenous formulation
Interval reported. 95% CI 0
Written into the record, not signed off as a reviewed claim.
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 happened in people◇Read from sources, not yet reviewed
How close this is to real life
The top step is something a person would feel or care about. The bottom is a guess from software. Filled steps are where evidence exists for this substance.
■Living longer, or avoiding a major eventEvidence recorded. Death, a heart attack, a stroke, a hospital stay.6 registered measures of this kind. No reviewed result.
□What a body can do day to dayNo evidence recorded. Walking, dressing, breathing, recovering.No registered study measures this.
□Measured performanceNo evidence recorded. How much was lifted, how far was run, how fast.No registered study measures this.
■Symptoms and quality of lifeEvidence recorded. Pain, tiredness, mood, sleep, as the person rated it.1 registered measure of this kind.
■A number that stands in for healthEvidence recorded. Cholesterol, blood sugar, bone density. A stand-in, not the thing itself.3 registered measures of this kind.
■A step measured inside a personEvidence recorded. Something measured in human tissue or human cells.A human record sits on the stored organism ladder.
■AnimalsEvidence recorded. Mice, rats, dogs. Useful for ideas, not proof about people.Stored records in C. elegans (roundworm), Drosophila (fruit fly), Mouse, Rat, Dog. A result in animals says what to test next. It does not say what happens in people.
■Cells in a dishEvidence recorded. Cells or chemistry on a bench, far from a whole body.Stored mechanism abstracts describe steps measured in cells or tissue.
□A guess from softwareNo evidence recorded. Nobody measured it. RNAWiki never publishes one as a finding.RNAWiki stores no prediction for this record. Software can suggest a link. RNAWiki does not publish one as a finding.
Higher on these steps means closer to something a person would feel. It does not mean better done.
What it changes in the body◇Read from sources, not yet reviewed
The path through the body
From what a person takes to what changes. A solid line is a step measured in people. A dashed line is a step nobody has measured that way.
Where a source records it acting
Blood and vessels: Inhibits the synthesis of vitamin K-dependent clotting factors (Factors II, VII, IX, and X) and the anticoagulant proteins C and S
US prescribing information · 0cbce382-9c88-4f58-ae0f-532a841e8f95 · read 2026-08-27
Start
Warfarin
What a person takes: Oral tablet in nine strengths, colour-coded by strength, plus an intravenous formulation.
The measurement behind this step
Once daily, with dose titrated against the international normalised ratio measured at intervals from days to weeks. The unusually large number of tablet strengths exists because the daily requirement varies more than tenfold between individuals and is adjusted in small increments.
Getting in
Absorbed completely, bound almost entirely to albumin
All of the tablet is absorbed and almost all of it travels stuck to a blood protein. Only the free fraction does anything, which is why other protein-bound drugs can shift its effect.
──Measured in people. Written by a person from the study named beside the step. Not signed off as a reviewed claim.
The measurement behind this step
Oral bioavailability is essentially complete, with peak concentration within 4 hours. Roughly 99% is bound to plasma albumin, and only the unbound fraction reaches the hepatocyte. The elimination half-life is about 40 hours for the racemate, but the pharmacodynamic delay is set by the half-lives of the clotting factors rather than by the drug.
It enters the liver cell, where the vitamin K cycle runs
The whole target pathway sits inside liver cells, in the membrane system where clotting factors are assembled before being released into the blood.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Warfarin enters hepatocytes and reaches the endoplasmic reticulum membrane, where vitamin K epoxide reductase, gamma-glutamyl carboxylase and the nascent vitamin K-dependent proteins are co-localised. The two enantiomers are handled by different cytochromes once inside: (S)-warfarin by CYP2C9 and (R)-warfarin mainly by CYP1A2 and CYP3A4.
Vitamin K is consumed each time a clotting factor is finished and has to be regenerated. Warfarin jams the regenerating enzyme, so the usable supply runs down.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Warfarin inhibits vitamin K epoxide reductase, encoded by VKORC1, which reduces vitamin K 2,3-epoxide back to the quinone and then the hydroquinone. The common VKORC1 -1639G>A promoter variant reduces enzyme expression and is the single largest genetic determinant of dose requirement; CYP2C9 variants are the second, acting on clearance of the more potent enantiomer.
Clotting factors are released in a form that cannot assemble
Without recycled vitamin K, the finishing step is skipped and the factors leave the liver unable to grip the calcium they need to build a clot on a membrane surface.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Gamma-glutamyl carboxylase can no longer carboxylate glutamate residues on factors II, VII, IX and X and on proteins C and S. Under-carboxylated factors cannot chelate calcium and therefore cannot bind to phospholipid membranes to assemble the tenase and prothrombinase complexes. Because protein C has a much shorter half-life than factor II, the earliest effect is a transient procoagulant state — the reason for bridging at initiation and the mechanism of warfarin-induced skin necrosis.
Clotting slows over days, measured by the INR, and strokes fall by two thirds
Nothing happens for a day or two while the already-working factors circulate. Once they wash out, the blood clots more slowly, and in atrial fibrillation the stroke rate falls by around two thirds.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Full effect requires clearance of the pre-existing carboxylated factors, with factor II having a half-life of roughly 60 hours, so 5 to 7 days are needed. Effect is monitored as the international normalised ratio, a standardised prothrombin time. Across 6 randomised trials in atrial fibrillation, adjusted-dose warfarin reduced stroke by 64% (95% CI 49% to 74%).
No suggested links are held for this record, so nothing is hidden from this path.
What we know
The record describes 5 steps from taking it to an effect in a person.
How we know it
Each step names the study behind it in the technical detail beside it.
What this does not prove
A change inside the body is a reason to look. It is not a result in a person.
Why it matters
A reader can see exactly where the chain stops being measured in people.
What we still do not know
No reviewed claim binds any of these steps to a named population.
What it would be like to take◇Read from sources, not yet reviewed
Felt, measured, or meaningful
Three different things that get called the same word. Registered studies measured all three, and mixing them is how a blood test becomes a health claim.
Felt
Things a person could notice without a test.
anxiety
Measured
Things only a test, a scale or a device shows.
creatinine
empagliflozin maximum measured concentration at steady state
body weight from baseline to 48 weeks
Meaningful
Things that change how a life goes, not only a number.
overall survival
incidence of stroke by one year
composite of recurrent vte or vte death at 36 months
composite of recurrent vte or vte death at 18 months
death
recurrent ischemic stroke and death
A registered study says what someone planned to measure. It does not say what they found. A number moving is not the same as a life going better. The two are shown apart here.
Felt, but not shown to help. A person notices a change. No study showed it leads anywhere good.
Measured, but not felt. A number moves. The person notices nothing. Both can be true.
Measured, but not shown to matter. A number moves in the good direction. Nobody showed that lives went better.
Matters, but takes years. The result that counts may take longer than anyone would keep watching.
Names that fit none of the three (30)
pharmacodynamic
losartan oral clearance and the formation clearance of e3174
These are harms, study-process measures, or names the rules did not recognise. They are shown rather than dropped.
What it would be like to take◇Read from sources, not yet reviewed
How long anything takes
Nine different lengths of time that get confused with each other. None of them is worked out from another.
Before anything is noticed.RNAWiki does not store this separately, and never works it out from another figure on this page.
Before a test result moves.RNAWiki does not store this separately, and never works it out from another figure on this page.
Before performance moves.RNAWiki does not store this separately, and never works it out from another figure on this page.
How long the result was watched.No finished study window is recorded for a study that tested this substance.
How long people took it.How long people actually took it is not stored. The study window is not the same thing.
How long people were followed.Follow-up length is not stored separately. It is never read off the study window, which would be a different thing.
How fast the body clears it. effective half-life 20 to 60 hours, mean about 40 hours hours
Read from the label, which states: “The terminal half-life of warfarin after a single dose is approximately 1 week; however, the effective half-life ranges from 20 to 60 hours, with a mean of about 40 hours.”
How long effects linger.RNAWiki does not store this separately, and never works it out from another figure on this page.
Beyond the studies. Nothing is recorded about the long term.
The longest finished study sets the edge of what anyone measured.
A study window is not how long people took it, and neither is how long they were followed. Where RNAWiki holds only one of the three, it shows one.
What is missing or unclear◇Read 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.
Anyone needing anticoagulation where the direct oral anticoagulants are not indicated — mechanical heart valves and moderate-to-severe mitral stenosis in particular — plus a large existing population stable on it. On the WHO Model List of Essential Medicines.
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: “Adequate and well-controlled studies with warfarin sodium have not been conducted in any pediatric population, and the optimum dosing, safety, and efficacy in pediatric patients is unknown.”
US prescribing information · bd6ea120-5d1c-4815-94f2-81e28dc6b7a9 · read 2026-08-30
On older people, the label states: “Of the total number of patients receiving warfarin sodium in controlled clinical trials for which data were available for analysis, 1885 patients (24.4%) were 65 years and older, while 185 patients (2.4%) were 75 years and older.”
US prescribing information · bd6ea120-5d1c-4815-94f2-81e28dc6b7a9 · read 2026-08-30
On people who are pregnant, the label states: “Risk Summary Warfarin sodium tablets, USP are contraindicated in women who are pregnant except in pregnant women with mechanical heart valves, who are at high risk of thromboembolism, and for whom the benefits of warfarin sodium may outweigh the risks [see Warnings and Precautions (5.7) ].”
US prescribing information · bd6ea120-5d1c-4815-94f2-81e28dc6b7a9 · read 2026-08-30
On people who are breastfeeding, the label states: “Risk Summary Warfarin was not present in human milk from mothers treated with warfarin from a limited published study.”
US prescribing information · bd6ea120-5d1c-4815-94f2-81e28dc6b7a9 · read 2026-08-30
On people with reduced liver function, the label states: “can potentiate the response to warfarin through impaired synthesis of clotting factors and decreased metabolism of warfarin.”
US prescribing information · bd6ea120-5d1c-4815-94f2-81e28dc6b7a9 · read 2026-08-30
On people with reduced kidney function, the label states: “Renal clearance is considered to be a minor determinant of anticoagulant response to warfarin.”
US prescribing information · bd6ea120-5d1c-4815-94f2-81e28dc6b7a9 · read 2026-08-30
Where the result stopped carrying
COAG: the flagship pharmacogenomic trial found an adjusted mean difference of -0.2 percentage points, p=0.91, and a race interaction running against the genotype arm
Warfarin lost to apixaban simultaneously on stroke, major bleeding and all-cause death in 18,201 patients
Aspirin, the alternative widely used for decades in atrial fibrillation, delivered 22% stroke reduction against warfarin's 64%
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 take◇Read 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 for a different goal
The studies measured something else entirely.
On this record: Some registered studies measured things that match no goal on this page.
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 (10)
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 take◇Read 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
Given by a clinician
❝ 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 tablet in nine strengths, colour-coded by strength, plus an intravenous formulation
✎ 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
Professional supervision is normally required. A regulator classifies this substance in a way that restricts how it is supplied.
❝ Quoted from a source
Where this came from
Copied from a source RNAWiki stored, with the source named.
Suppression classes recorded: S3, S6.
No source is stored against this line.
What is in the pack
Once daily, with dose titrated against the international normalised ratio measured at intervals from days to weeks. The unusually large number of tablet strengths exists because the daily requirement varies more than tenfold between individuals and is adjusted in small increments.
✎ 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 take◇Read from sources, not yet reviewed
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.
·Worth asking a clinician aboutWritten into the record from the studies named on this page
The US label carries a boxed warning for bleeding risk. The narrow therapeutic index, tenfold inter-individual dose variability, direct dietary antagonism by vitamin K, and a very long interaction list make it one of the most monitoring-intensive drugs in common use. Warfarin-induced skin necrosis at initiation reflects the shorter half-life of protein C relative to factor II. It is teratogenic and contraindicated in pregnancy. Reversal is with vitamin K, and urgently with prothrombin complex concentrate.
Nobody counted how many people took this and were fine, so this cannot be turned into a rate.
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.
Warfarin appears in spontaneous reports to regulators. Across the 10 most-reported reaction terms, 104 reaction mentions were counted. One report can name several reactions.
The recorded terms (10)
international normalised ratio increased — 19 reaction mentions
open-targets-adr · recorded 2026-06-24 · a recorded source, not a stored snapshot
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 unclear◇Read 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 tablet in nine strengths, colour-coded by strength, plus an intravenous formulation
✎ 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
The unusually large number of tablet strengths exists because the daily requirement varies more than tenfold between individuals and is adjusted in small increments.
✎ 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 which forms are sold and how they compare.
No source is stored against this line.
What is recorded as being sold
149 products list this as an active ingredient in the United States drug directory. 149 of them contain it and nothing else.
FDA National Drug Code directory · 76282-334 · read 2026-08-29
They are sold as powder and tablet, taken oral.
FDA National Drug Code directory · 76282-334 · read 2026-08-29
The regulator's established pharmacologic class for it is vitamin k antagonist [epc] and vitamin k inhibitors [moa].
FDA National Drug Code directory · 76282-334 · read 2026-08-29
75 published labels name it as an active ingredient. 75 of them describe this substance alone, which is where its own label text on this page comes from.
US prescribing information · bd6ea120-5d1c-4815-94f2-81e28dc6b7a9 · read 2026-08-29
Those labels are classed as human prescription drug.
US prescribing information · bd6ea120-5d1c-4815-94f2-81e28dc6b7a9 · read 2026-08-29
Warfarin Sodium is scored tablets at Scored tablets: 1, 2, 2.5, 3, 4, 5, 6, 7.5, or 10 mg, recorded as prescription product; fda label in effect 2025-06-17 in the United States.
US prescribing information · 0cbce382-9c88-4f58-ae0f-532a841e8f95 · read 2026-08-27
Recorded price in US: 0.08667–0.09714 USD per one unit as the pricing file counts it — a tablet, capsule, patch or single item, across 93 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 take◇Read 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.
Self-experiment planning is not offered for a prescription or clinician-supervised medicine. The questions below are for a clinician or pharmacist.
Questions worth asking
Which of the trials of Warfarin 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 unclear◇Read from sources, not yet reviewed
Claims that go past the evidence
Things said about this substance that sound reasonable, and the exact step that is missing between the evidence and the claim.
✗Goes past the evidence
That genotype-guided warfarin dosing improves clinical outcomes — no trial has been sized to measure stroke or major bleeding, and the one clinical composite was driven by laboratory excursions
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That EU-PACT and COAG conflict — they used different comparators, and the genotype only helped where the alternative was a fixed loading dose
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That the GIFT result generalises across ancestries — the population was 91.0% white and COAG found the genotype-guided strategy performed worse in Black patients
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That warfarin has been superseded generally — it remains superior in rheumatic valve disease and is the only option for mechanical valves
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
What is missing or unclear◇Read 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 Warfarin 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 people◇Read 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.
Every line above can be traced to the study named beside it. Follow the link and read it.
A 64% stroke reduction in atrial fibrillation, across 6 randomised trials
In plain words
Pooling every randomised trial in atrial fibrillation, adjusted-dose warfarin cut strokes by about two thirds against control, and by about 40% against aspirin and similar drugs.
What was measured
Relative reduction in stroke against control and against antiplatelet therapy, pooled across randomised trials
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Hart and colleagues pooled 29 randomised trials with 28,044 participants, mean age 71 and mean follow-up 1.5 years, in non-valvular atrial fibrillation. Against control, adjusted-dose warfarin across 6 trials and 2,900 participants reduced stroke by 64% (95% CI 49% to 74%), and antiplatelet agents across 8 trials and 4,876 participants reduced it by 22% (6% to 35%). Directly compared across 12 trials and 12,963 participants, adjusted-dose warfarin was 39% better than antiplatelet therapy (22% to 52%). Absolute increases in major extracranial haemorrhage were 0.3% per year or less, and were smaller than the absolute reductions in stroke.
Written into the record, not signed off as a reviewed claim
COAG: genotype-guided dosing did not beat a clinical algorithm, and was worse in Black patients
In plain words
The flagship American trial of pharmacogenomic warfarin dosing found no advantage at all over dosing that used clinical information alone. In Black participants, the genotype-guided arm did worse.
What was measured
Percentage of time in the therapeutic INR range from day 4 or 5 through day 28
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
COAG randomly assigned 1,015 patients to warfarin doses over the first 5 days determined by an algorithm including both clinical variables and genotype, or by one using clinical variables only. Patients and clinicians were unaware of the dose for the first 4 weeks. The primary outcome, percentage of time the INR was in the therapeutic range from day 4 or 5 through day 28, was 45.2% in the genotype-guided group against 45.4% in the clinically guided group: adjusted mean difference -0.2 (95% CI -3.4 to 3.1), p=0.91. There was no difference among patients for whom the two algorithms predicted doses differing by 1 mg per day or more. There was a significant interaction between dosing strategy and race (p=0.003): among Black patients, time in therapeutic range was lower in the genotype-guided group. Rates of the combined outcome of INR of 4 or more, major bleeding or thromboembolism did not differ.
Written into the record, not signed off as a reviewed claim
EU-PACT: the same idea worked, against a fixed loading dose instead
In plain words
A European trial published in the same issue found genotype-guided dosing clearly better. Its comparison group was a fixed three-day loading regimen rather than a clinical algorithm, and that difference is the whole explanation.
What was measured
Percentage of time in the therapeutic INR range of 2.0 to 3.0 during the first 12 weeks
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
EU-PACT recruited 455 patients with atrial fibrillation or venous thromboembolism, randomising 227 to genotype-guided dosing using point-of-care testing for CYP2C9*2, CYP2C9*3 and VKORC1 -1639G>A for the first 5 days, and 228 to a control group receiving a 3-day loading-dose regimen. After initiation all patients were managed by routine practice. Mean time in the therapeutic INR range of 2.0 to 3.0 over the first 12 weeks was 67.4% in the genotype-guided group against 60.3% in the control group: adjusted difference 7.0 percentage points (95% CI 3.3 to 10.6). Read alongside COAG, the pair establishes that genotype-guided dosing beats a fixed loading regimen and does not beat a clinical algorithm — so the value of the genotype depends entirely on what it is being compared with.
Written into the record, not signed off as a reviewed claim
GIFT: a clinical benefit, in a narrow surgical population, driven by INR excursions
In plain words
A third trial, in older patients starting warfarin after hip or knee replacement, did find fewer adverse events with genotype-guided dosing. Most of the difference was in over-anticoagulation rather than in bleeding or clots.
What was measured
Composite of major bleeding, INR of 4 or greater, venous thromboembolism or death after arthroplasty
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
GIFT randomised 1,650 patients aged 65 or older starting warfarin for elective hip or knee arthroplasty at 6 United States centres, genotyping VKORC1 -1639G>A, CYP2C9*2, CYP2C9*3 and CYP4F2 V433M, in a 2-by-2 factorial design also randomising to an INR target of 1.8 or 2.5. Of 1,597 who received warfarin and completed, 87 of 808 (10.8%) in the genotype-guided group and 116 of 789 (14.7%) in the clinically guided group met at least one component of the composite of major bleeding, INR of 4 or greater, venous thromboembolism or death: absolute difference 3.9 percentage points (95% CI 0.7 to 7.2), p=0.02, relative rate 0.73 (0.56 to 0.95). Component counts were 2 against 8 for major bleeding (relative rate 0.24, 0.05 to 1.15), 56 against 77 for INR of 4 or greater (0.71, 0.51 to 0.99), 33 against 38 for venous thromboembolism (0.85, 0.54 to 1.34), and no deaths. The composite was driven by the INR component; the population was 91.0% white, which matters given the COAG race interaction.
Written into the record, not signed off as a reviewed claim
Time in therapeutic range is the surrogate, and it is not the outcome
In plain words
Two of the three pharmacogenomic trials measured how long the blood test stayed in range, not how many people bled or had a stroke. Those are different things, and the trials were not large enough to measure the second.
What was measured
That improving time in therapeutic INR range with a genotype test prevents strokes and bleeds — none of the three trials was sized to measure that, and the one clinical composite was driven by laboratory excursions
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
COAG and EU-PACT both used percentage of time in the therapeutic INR range as their primary outcome. That measure correlates with clinical events across populations but is not itself an event, and neither trial — at 1,015 and 455 patients respectively over weeks — had the size to detect a difference in stroke or major bleeding. COAG did report that the combined outcome of INR of 4 or more, major bleeding or thromboembolism did not differ. GIFT used a clinical composite, and 133 of the 203 events it counted were INR excursions of 4 or greater rather than bleeds or clots, with major bleeding at 2 against 8 events on a confidence interval spanning 0.05 to 1.15. The consistent picture across all three is a surrogate that sometimes moves and clinical events that have never been shown to.
Written into the record, not signed off as a reviewed claim
Warfarin lost to apixaban on stroke, on bleeding and on death simultaneously
In plain words
In more than eighteen thousand patients with atrial fibrillation, a newer anticoagulant produced fewer strokes, less major bleeding and fewer deaths than well-managed warfarin, all at once.
What was measured
Stroke or systemic embolism, major bleeding and all-cause death per year, apixaban versus warfarin
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
ARISTOTLE randomised 18,201 patients with atrial fibrillation and at least one additional stroke risk factor to apixaban 5 mg twice daily or warfarin targeted to an INR of 2.0 to 3.0, median follow-up 1.8 years. Stroke or systemic embolism occurred at 1.27% per year against 1.60% (hazard ratio 0.79, 95% CI 0.66 to 0.95; p<0.001 for non-inferiority, p=0.01 for superiority). Major bleeding was 2.13% against 3.09% per year (0.69, 0.60 to 0.80, p<0.001) and death from any cause 3.52% against 3.94% (0.89, 0.80 to 0.99, p=0.047). The difference was concentrated in haemorrhagic stroke, 0.24% against 0.47% per year (0.51, 0.35 to 0.75, p<0.001); ischaemic or uncertain-type stroke was 0.97% against 1.05% (0.92, 0.74 to 1.13, p=0.42) and not significantly different. So the superiority came from bleeding into the brain, not from better clot prevention.
Written into the record, not signed off as a reviewed claim
Where warfarin still wins: a factor Xa inhibitor lost to it in rheumatic valve disease
In plain words
The idea that warfarin has been superseded is population-specific. In rheumatic heart disease with atrial fibrillation, a trial of over four thousand patients found more deaths on rivaroxaban than on a vitamin K antagonist.
What was measured
Composite of stroke, systemic embolism, myocardial infarction or death, rivaroxaban versus vitamin K antagonist in rheumatic heart disease
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
INVICTUS randomised 4,565 patients with rheumatic heart disease and atrial fibrillation to rivaroxaban or a dose-adjusted vitamin K antagonist. The trial found the vitamin K antagonist superior, with the difference driven by death. Mechanical prosthetic heart valves are the other setting where a direct oral anticoagulant was tested against warfarin and performed worse, and the direct oral anticoagulants carry a labelled contraindication there. Warfarin remains on the WHO Model List of Essential Medicines, and at about nine cents a tablet against US$5.52 for apixaban it is also the only anticoagulant most of the world can afford at scale.
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What is not here
3 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 it may clash with — found nothing in the sources checked.
Other ways to the same goal — 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.
The older medicine-wide conclusion held in this record
Written for a clinical reader, and about the medicine as a whole rather than about one indication, population and set of trials. RNAWiki does not treat it as a programme conclusion and no reviewer has signed it off in that form. It is here word for word because it is what the record holds.
A vitamin K antagonist that reduces stroke in atrial fibrillation by 64% across 6 randomised trials, and the subject of a genuine reversal: genotype-guided dosing beat a fixed loading regimen in EU-PACT and did not beat a clinical algorithm in COAG, where among Black participants it performed worse.
Recorded evidence blocks (15)
Q2
What did Warfarin's largest trial (1000000 people) and its longest (27 years) measure?
1000000 people in Warfarin's largest registered study, 27 years in its longest registered window, measuring Percentage of Participants With Composite Endpoint of Stroke, Systemic Embolic Stroke (SEE), Myocardial Infarction (MI) and Cardiovascular (CV) Mortality From Randomization to End of Follow up. ClinicalTrials.gov · 2026-09-01
101 phase1, 76 phase3, 69 phase4, 60 na, 60 na or unstated, 47 phase2, 2 early phase1; NCT00162474; 2030-12. Last human test completed 2026, NCT04736420.
Interpretation These counts include studies where Warfarin was a comparison treatment, a background treatment or an exposure in an observational study, and the longest window may be a planned end date. Trial roles have not yet been classified for this record.
Show the evidence
phase1
101
phase3
76
phase4
69
na
60
na or unstated
60
phase2
47
2 more recorded rows
early phase1
2
Last recorded human testNCT04736420
2026-06-15
recorded 2026-09-01 · last checked 2026-09-04
Q3
From C. elegans to human: where has Warfarin shown lifespan?
Interpretation Percentage of Participants With Composite Endpoint of Stroke, Systemic Embolic Stroke (SEE), Myocardial Infarction (MI) and Cardiovascular (CV) Mortality From… — the recorded outcome words.
Show the evidence
C. elegans
lifespan
Drosophila
lifespan
mouse
mechanism-only
rat
mechanism-only
dog
mechanism-only
humanNCT02072434
lifespan; Percentage of Participants With Composite Endpoint of Stroke, Systemic Embolic Stroke (SEE), Myocardial Infarction (MI) and Cardiovascular (CV) Mortality From Randomization to End of Follow up; 407
recorded 2026-09-01 · last checked 2026-09-04
Q4
27 of Warfarin's trials stopped: safety, futility/efficacy, accrual/recruitment, funding/business, other?
safety (4), futility/efficacy (1), accrual/recruitment (14), funding/business (1) and other (7): Warfarin's stop wording, clustered. ClinicalTrials.gov · 2026-09-01
"Enrolment was halted prematurely because of the observed excess in recurrences"; 27 of 407 registered studies
Show the evidence
Trial
NCT00428441
terminated; "Enrolment was halted prematurely because of the observed excess in recurrences"
NCT00580216
terminated; "early discontinuation based on strategic sponsor decision not driven by any safety concern"
NCT00673439
terminated; "study terminated due to low accrual"
NCT00790842
terminated; "Slow enrollment"
NCT00957242
terminated; "Excess of mortality in the treatment group created safety concerns."
NCT01036802
terminated; "Difficulty in accruing subjects"
14 further recorded trials
NCT01164046
terminated; "Due to slow inclusion of patients"
NCT01668901
withdrawn; "Financial problem"
NCT01868243
terminated; "because a significant decrease of viable candidates for the study."
NCT02054936
withdrawn; "Change in standard of care, no possibility of recruitment"
NCT02561897
terminated; "Did not meet enrolment target for phase 1"
NCT02664155
terminated; "recruiting difficulties"
NCT02696226
terminated; "Poor enrollment"
NCT02872649
terminated; "safety reasons"
NCT03196349
terminated; "Lack of enrollment"
NCT03358706
terminated; "The study was stopped as all post-marketing commitments had been fulfilled or released"
NCT03465735
terminated; "Due to lack of recruitment of eligible participants"
NCT03536208
withdrawn; "no accrual for over 12 months"
NCT03566303
terminated; "Coronavirus Pandemic"
NCT03673605
withdrawn; "No patients Enrollment"
recorded 2026-09-01 · last checked 2026-09-04
Q5
Human studies of Warfarin used warfarin plus ABT-335 plus rosuvastatin 5 mg — over how long?
20 recorded entries; human; also "warfarin plus ABT-335 plus rosuvastatin 5 mg", "warfarin plus ABT-335 plus rosuvastatin 20 mg", "Warfarin 25 mg"
Show the evidence
human
NCT00487136
warfarin plus ABT-335 plus rosuvastatin 5 mg
NCT00487136
warfarin plus ABT-335 plus rosuvastatin 20 mg
NCT01111331
Warfarin 25 mg
NCT01178853
Warfarin 5mg + Rosuvastatin 40 mg once daily (QD)
NCT01178853
Warfarin 5 mg + Pitavastatin 4mg once daily (QD)
NCT01452347
warfarin 1mg
14 more recorded rows
humanNCT01452347
warfarin 5mg
humanNCT01452347
warfarin 3mg
humanNCT02164864
Warfarin 3mg
humanNCT02164864
Warfarin 5mg
humanNCT02164864
Warfarin 1mg
humanNCT02240927
Enoxaparine and 2.5 mg Warfarin
humanNCT02240927
Clexane and 2.5 mg Warfarin
humanNCT02240927
Enoxaparine and 4mg Warfarin
humanNCT02240927
Clexane and 4 mg Warfarin
humanNCT02240953
Warfarin + ASA 100 mg + PPI
humanNCT02240953
Warfarin + ASA 300 mg + PPI
humanNCT03058419
Warfarin 10 mg
humanNCT04235569
Warfarin Sodium 5 MG
humanNCT04235569
Marevan 5mg
recorded 2026-09-01 · last checked 2026-09-04
Q6
Did Warfarin move Horvath, and by how much?
Horvath: "The present study examines the associations of 4 epigenetic clocks-Horvath, Hannum, PhenoAge, GrimAge-with a wide range of clinical phenotypes (walking speed, grip strength, Fried frailty, polypharmacy, Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MOCA), Sustained Attention Reaction Time,…" Europe PMC · epigenetic clock search · 2021-04-01
2 recorded sentences; 2021, 2018; biomarker
Show the evidence
Horvath
PMID 33211845
2021; "The present study examines the associations of 4 epigenetic clocks-Horvath, Hannum, PhenoAge, GrimAge-with a wide range of clinical phenotypes (walking speed, grip strength, Fried frailty, polypharmacy, Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MOCA), Sustained Attention Reaction Time, 2-choice reaction time), and with all-cause mortality at up to 10-year follow-up, in…"
PMID 29967575
2018; "Consequently, previous findings regarding the effect of primary motor cortex excitability on choice bias and response times could not be replicated with a more controlled experimental design that is recommended for tDCS studies (Horvath et al., 2015)."
recorded 2021-04-01 · last checked 2026-09-04
Q7
More Warfarin was worse in human: at what point?
U-shaped in human: "This study also reveals a reverse U-shaped association between urbanization (URB) and ERD rate, with ERD rate peaking in countries with diverse traffic conditions and less road choice." Europe PMC · dose-response search · 2026-08-01
3 recorded sentences naming Warfarin; U-shaped, dose response
Show the evidence
U-shaped
PMID 41568877
"This study also reveals a reverse U-shaped association between urbanization (URB) and ERD rate, with ERD rate peaking in countries with diverse traffic conditions and less road choice."
PMID 42307528
"Due to its acute U-shaped curve, the oral RAE ETT was our first choice."
dose responsePMID 42647228
"Despite its clinical efficacy, warfarin therapy is associated with a narrow therapeutic index, substantial interindividual variability in dose response, numerous drug interactions, and significant hemorrhagic risk."
recorded 2026-08-01 · last checked 2026-09-04
Q8
Which of adjudicated incidence of bleeding events, alanine aminotransferase and anxiety did Warfarin's trials measure?
adjudicated incidence of bleeding events, alanine aminotransferase and anxiety lead 40 outcome terms across Warfarin's trials. ClinicalTrials.gov · 2026-09-01
flurbiprofen oral clearance, siponimod oral clearance, incidence of stroke by one year, composite of recurrent vte or vte death at 36 months, composite of recurrent vte or vte death at 18 months and recurrent venous thromboembolism follow.
Show the evidence
overall survival
1
pharmacodynamic
1
losartan oral clearance and the formation clearance of e3174
1
flurbiprofen oral clearance
1
siponimod oral clearance
1
incidence of stroke by one year
1
14 more recorded rows
composite of recurrent vte or vte death at 36 months
1
composite of recurrent vte or vte death at 18 months
Warfarin oral clearance; Frequency of patients with structural/functional abnormalities of bioprosthetic valves; latest 2030-12-31
Show the evidence
Trial
NCT00162474
"Determinants of Warfarin Metabolism"; n 1000; "Warfarin oral clearance"; 2030-12
NCT02318342
"Assessment of TRanscathetEr and Surgical Aortic BiOprosthetic Valve Thrombosis and Its TrEatment With Anticoagulation"; n 3000; "Frequency of patients with structural/functional abnormalities of bioprosthetic valves"; 2028-12
NCT03636295
"Low INR to Minimize Bleeding With Mechanical Valves Trial"; n 2625; "Thrombosis/thromboembolism"; 2026-12-31
NCT03862859
"The Danish Warfarin-Dialysis Study - Safety and Efficacy of Warfarin in Patients With Atrial Fibrillation on Dialysis"; n 718; "Primary efficacy outcome - Number of participants with transient ischemic attack, fatal and non-fatal ischaemic or unspecific stroke"; 2027-01
NCT04045093
"Dabigatran for Mitral Stenosis Atrial Fibrillation"; n 370; "Composite of stroke, systemic embolism, myocardial infarction, and death from cardiovascular or unknown cause."; 2027-09-30
NCT04284839
"The Direct Oral Anticoagulation Versus Vitamin K Antagonist After Cardiac Surgery Trial"; n 3500; "Major Bleeding"; 2027-06
14 further recorded trials
NCT04847752
"Study of Predictive Factors Related to Prognosis of Patients With Ischemic Stroke Due to Large-artery Atherosclerosis"; n 1000; "all-cause mortality"; 2028-12-31
NCT05643651
"Rivaroxaban for Children Aged Over 2 Years With Giant Coronary Artery Aneurysms After Kawasaki Disease"; n 100; "Composite of new thrombosis in coronary arteries, major bleeding, clinically relevant non-major bleeding event or major adverse cardiovascular event"; 2027-09-01
NCT05782270
"Antithrombotic Therapy After Coronary Artery Bypass Grafting Combined With Coronary Endarterectomy"; n 202; "Rate of coronary endarterectomy-targeted graft patency."; 2026-05-30
NCT05794399
"Anticoagulation in Post MI LV Thrombus Trial in Nepal"; n 196; "LV thrombus resolution"; 2026-04
NCT05995600
"Comparison of Clopidogrel-based Antiplatelet Therapy Versus Warfarin As Secondary Prevention Strategy for AntiPhospholipid Syndrome-related STROKE"; n 200; "Composite endpoint"; 2029-03
NCT06402851
"Vitamin K AntagonISt, Factor Xa Inhibitor or No Anticoagulation in Atrial Fibrillation and DIalytic End-stage Renal DiseasE (VISIONAIRE)"; n 1500; "Primary efficacy endpoint"; 2026-12
NCT06449469
"The Nordic Aortic Valve Intervention Trial 4 (NOTION-4)"; n 352; "HALT after 1 year"; 2030-04-01
NCT06515730
"Treatment With Apixaban Versus Warfarin in Patients With Left Ventricular Thrombus After Acute Myocardial Infarction"; n 212; "Number and proportion of participants with thrombus resolution at 3 months"; 2028-07-01
NCT06655376
"Aspirin and Hemocompatibility Events in Chronic Advanced Heart Failure Patients With Assist Device"; n 128; "Number of survival free patients of any major hemocompatibility related adverse events."; 2027-04-01
NCT06738992
"Safety and Effectiveness of Early Aspirin Administration After Mitral Valve Repair"; n 384; "Clinical thromboembolic events"; 2027-12-31
NCT06915610
"Reengineering Cervical Cancer Screening for the 21st Century: Joint Action for a Novel Up-to-date and Sustainable Screening Program"; n 5700; "Adherence to screening, after the first invitation for CCS in the study"; 2027-03-31
NCT06934213
"Experiment 3: Mixed vs Blocked; Dashboard Paradigm"; n 50; "Response Time (RT)"; 2029-06-30
NCT07081035
"Trial of Low-intensity Anticoagulation to Reduce GI or Other Bleeding Complications With Equivalent Therapeutic Efficacy in HeartMate 3 LVAD Patients"; n 94; "Incidence of composite hemocompatibility-related events"; 2029-01
NCT07115901
"Guaranteed Income to Boost HIV Care Continuity and Suppression Post-Jail Release"; n 33; "HIV viral suppression"; 2027-02-25
recorded 2026-09-01 · last checked 2026-09-04
Q10
Which running trial of Warfarin could settle lifespan?
NCT06655376 measures Number of survival free patients of any major hemocompatibility related adverse events., reading out 2027-04-01.
3 open trials; n 128; "Aspirin and Hemocompatibility Events in Chronic Advanced Heart Failure Patients With Assist Device"
Show the evidence
Trial
NCT06655376
"Aspirin and Hemocompatibility Events in Chronic Advanced Heart Failure Patients With Assist Device"; n 128; "Number of survival free patients of any major hemocompatibility related adverse events."; 2027-04-01
NCT04847752
"Study of Predictive Factors Related to Prognosis of Patients With Ischemic Stroke Due to Large-artery Atherosclerosis"; n 1000; "all-cause mortality"; 2028-12-31
NCT07471139
"SWITCH: Apixaban vs Vitamin K in HM3"; n 460; "Survival free of major hemocompatibility related adverse event"; 2029-08
Q11
Which 172 trials of Warfarin posted no result?
Posted no result
172 of 172 completed trials
Registrations
NCT00000517, NCT00000463, NCT00000539, NCT00697151, NCT00005684 and NCT00000614, and 166 more
Completion dates
oldest 1991-06; newest 2024-06-28
Show the evidence
Trial
NCT00000517
1991-06
NCT00000463
1998-12
NCT00000539
1999-03
NCT00697151
2000-06
NCT00005684
2001-01
NCT00000614
2004-08
14 further recorded trials
NCT00689520
2005-01
NCT00097357
2005-12
NCT00001713
2006-01
NCT00216866
2006-03
NCT00973323
2006-03
NCT00380120
2006-06
NCT00438230
2006-09
NCT02779348
2006-12
NCT00973245
2007-01
NCT00157651
2007-03
NCT00404274
2007-03-18
NCT00487136
2007-07
NCT00533026
2007-10
NCT00623987
2008-01
Q12
At the median, Warfarin's trials enrolled 100 people — anything larger?
Median enrolment
100
Largest enrolment
1000000
Registered trials counted
399
Q13
What do 104 spontaneous reports say about Warfarin — 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.
Warfarin appears in spontaneous reports to regulators. Across the 10 most-reported reaction terms, 104 reaction mentions were counted: international normalised ratio increased 19; drug interaction 15; anaemia 14; prothrombin time prolonged 10. open-targets-adr · CHEMBL1200772 · 2026-06-24
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international normalised ratio increased
19
drug interaction
15
anaemia
14
prothrombin time prolonged
10
haemorrhage subcutaneous
9
haemoglobin decreased
8
4 more recorded rows
melaena
8
gastrointestinal haemorrhage
7
haemorrhage
7
labelled drug-drug interaction medication error
7
recorded 2026-06-24 · last checked 2026-09-04
Q14
Warfarin and CYP2C9: shared by which compounds?
CYP2C9 appear in Warfarin's recorded interaction sentences, 9 in all. openfda-label+europepmc · 2026-08-30
The CYP450 isozymes involved in the metabolism of warfarin include CYP2C9, 2C19, 2C8, 2C18, 1A2, and 3A4.
pharmacokinetics
CYP2C9, a polymorphic enzyme, is likely to be the principal form of human liver CYP450 that modulates the in vivo anticoagulant activity of warfarin.
pharmacokinetics
Patients with one or more variant CYP2C9 alleles have decreased S-warfarin clearance [see Clinical Pharmacology (12.5) ].
clinical_pharmacology
Patient age was the most important determinant of warfarin requirement in these patients, with a progressively lower warfarin requirement with increasing age. 12.5 Pharmacogenomics CYP2C9 and VKORC1 Polymorphisms The S -enantiomer of warfarin is mainly metabolized to 7-hydroxywarfarin by CYP2C9, a polymorphic enzyme.
clinical_pharmacology
The variant alleles, CYP2C9*2 and CYP2C9*3, result in decreased in vitro CYP2C9 enzymatic 7-hydroxylation of S-warfarin.
clinical_pharmacology
The frequencies of these alleles in Caucasians are approximately 11% and 7% for CYP2C9*2 and CYP2C9*3, respectively.
3 more recorded rows
CYP2C9clinical_pharmacology
Other CYP2C9 alleles associated with reduced enzymatic activity occur at lower frequencies, including *5, *6, and *11 alleles in populations of African ancestry and *5, *9, and *11 alleles in Caucasians.
CYP2C9clinical_pharmacology
VKORC1 and CYP2C9 gene variants generally explain the largest proportion of known variability in warfarin dose requirements.
CYP2C9clinical_pharmacology
CYP2C9 and VKORC1 genotype information, when available, can assist in selection of the initial dose of warfarin [see Dosage and Administration (2.3) ].
recorded 2026-08-30 · last checked 2026-09-04
Q15
Was Warfarin studied with exercise?
exercise is named in Warfarin's label sentences: "In the ‘Choice’ or subjective condition, participants received the reward associated with the chosen option, irrespective of how it compared to the unchosen option, allowing greater freedom to exercise subjective preferences in decision policy." openfda-label+europepmc · 2026-08-30
1 recorded statement; exercise
Show the evidence
exercise
In the ‘Choice’ or subjective condition, participants received the reward associated with the chosen option, irrespective of how it compared to the unchosen option, allowing greater freedom to exercise subjective preferences in decision policy.
recorded 2026-08-30 · last checked 2026-09-04
Q16
What is recorded about Warfarin and mTOR?
"They also highlight the need for caution in choice, dose and timing of mTOR inhibitors as senotherapeutics in diabetic patients.</p>" — where Warfarin and mTOR appear together. Europe PMC · pathway abstract search · 2026-03-18
"They also highlight the need for caution in choice, dose and timing of mTOR inhibitors as senotherapeutics in diabetic patients.</p>"
autophagyPMID 41994101
"We propose that the cellular choice between autophagy-assisted survival and autophagy-dependent death is not simply black and white but exists within a dynamic balance called the Arsenic Contextual Triad-comprising chemical form, exposure pattern (dose and duration), and the cell's oncogenic background."
mTORPMID 40960531
"Therapeutic choice is context-specific: if ROS is facilitating tumor survival through PI3K/AKT activation, combination with mTOR inhibitors could be best; if ROS initiates pro-apoptotic signaling, ROS-generating strategies, including certain chemotherapies, could be better."
autophagyPMID 41384306
"The present study proposed a combined therapy targeting autophagy and glycolysis might become a new choice for clinical treatment of IBD."
AMPKPMID 40887103
"Our study is the first to demonstrate that glycyrrhizin exerts both protective and therapeutic effect on CI-AKI by inhibiting tubular epithelial cell ferroptosis <i>via</i> HMGB1/AMPK/Beclin-1 axis, providing a potential choice for treating CI-AKI."
mTORPMID 33293795
"These results indicated that Res is a feasible and effective choice for SSc and therapeutic target of mTOR could be a potential alternative for treatment of SSc."
recorded 2026-03-18 · last checked 2026-09-04
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