This page shows what was measured, who it was measured in, and what that does not settle.
What Hydralazine does in the body
High blood pressure, including when it must be brought down urgently; and, combined with a nitrate, heart failure
Hydralazine relaxes the muscle wrapped around small arteries, so those arteries widen and blood pressure falls. Exactly how it does this is still not settled; the prescribing information says only that it interferes with the calcium movements the muscle needs in order to contract. Because it opens arteries and barely touches veins, more blood reaches the heart than leaves it under pressure, so the heart speeds up and pumps harder in response, and the kidney reads the falling pressure as a signal to retain salt. Those two reflexes fight the drug, which is why it is usually combined with something that slows the heart and something that removes salt.
What happened in people
Increased heart rate, stroke volume, cardiac output and plasma renin activity following arteriolar dilatation, per the label
✎ 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.
That hydralazine alone carries the A-HeFT survival benefit, when the trial tested a fixed combination with a nitrate
Where it acts
Arteriolar smooth muscle — hydralazine dilates the small arteries far more than the veins, which is why it raises cardiac output rather than dropping it
Kind of result
Living longer, or avoiding a major event
Supervision
RNAWiki has not recorded a supervision or regulatory status for this substance.
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.
A limit recorded against this substance. Not signed off as a reviewed claim.
The four opening statements run to 146 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 21 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
Healthy ageing
…Waiting for a reviewer2 registered study measure of this kind. No reviewed result yet.
∅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.
∅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.
Recovery
∅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.
∅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.
Which registered measures put each goal on this table
Healthy ageing
all cause hospitalization or all cause mortality; all cause mortality
Recovery
recovery from heartlogic alert
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
… Waiting for a reviewer
2 registered study measure of this kind. No reviewed result yet.
∅ Nothing in the sources checked
No registered study lists a performance measure for this goal.
— Not recorded
Harms were not a registered measure for this goal.
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.
Weighted composite of death from any cause, first hospitalisation for heart failure and change in quality of life, in black patients with NYHA class III or IV heart failure and dilated ventricles, on top of standard therapy
Composite −0.1 ± 1.9 against −0.5 ± 2.0, p=0.01; all-cause mortality 6.2% against 10.2%, p=0.02 (hazard ratio 0.57, p=0.01); first heart failure hospitalisation 16.4% against 22.4%, p=0.001
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 trial tested the fixed combination and cannot attribute the effect to hydralazine alone. It was stopped early for the mortality difference, which tends to overstate effect size. It enrolled only black patients and therefore cannot establish that the benefit is specific to that group. The BiDil label notes little experience in NYHA class IV.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet, and intramuscular or intravenous injection for urgent reduction of severe hypertension; also available as a fixed-dose oral combination with isosorbide dinitrate
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
Mortality with hydralazine 300 mg plus isosorbide dinitrate 160 mg daily against enalapril 20 mg daily, in men with chronic congestive heart failure on digoxin and diuretics
Two-year mortality 25% on hydralazine plus isosorbide dinitrate against 18% on enalapril, p=0.016 — a 28% reduction favouring enalapril; overall mortality tended lower on enalapril at p=0.08
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. The combination arm did better on two physiological measures: peak exercise oxygen consumption increased only in that arm (p<0.05) and ejection fraction rose more during the first 13 weeks. The enalapril advantage came from fewer sudden deaths and was more prominent in less symptomatic patients. The BiDil label reports that retrospective analysis placed the enalapril advantage in the 574 white participants with essentially no difference among the 215 black participants — a post-hoc subgroup that became the basis for a race-specific indication.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet, and intramuscular or intravenous injection for urgent reduction of severe hypertension; also available as a fixed-dose oral combination with isosorbide dinitrate
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
Maternal and perinatal outcomes with hydralazine against other short-acting antihypertensives — principally nifedipine and labetalol — for severe hypertension in pregnancy
✗ The study did not show it
Who was studied
Magee LA et al., meta-analysis of hydralazine for severe hypertension in pregnancy (BMJ 2003;327:955-960)
How many people
893
Study design
Meta-analysis of 21 randomised controlled trials published 1966 to September 2002
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Hydralazine associated with more maternal hypotension (RR 3.29, 95% CI 1.50 to 7.23), more caesarean sections (1.30, 1.08 to 1.59), more placental abruption (4.17, 1.19 to 14.28), more maternal oliguria (4.00, 1.22 to 12.50), more adverse fetal heart rate effects (2.04, 1.32 to 3.16) and more low one-minute Apgar scores (2.70, 1.27 to 5.88)
Repeated elsewhere
Partially 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. The authors state their results are not robust enough to guide clinical practice, report significant heterogeneity between trials and differences in methodological quality, and call for adequately powered trials with labetalol and nifedipine described as showing the most promise. Hydralazine showed a trend towards less persistent severe hypertension than labetalol and less neonatal bradycardia. This is a synthesis of small trials, not a single adequately powered comparison.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet, and intramuscular or intravenous injection for urgent reduction of severe hypertension; also available as a fixed-dose oral combination with isosorbide dinitrate
Interval reported. 95% CI 1
Written into the record, not signed off as a reviewed claim.
RNAWiki holds 3 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.3 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 lifeNo evidence recorded. Pain, tiredness, mood, sleep, as the person rated it.No registered study measures this.
■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.1 registered measure inside human tissue.
■AnimalsEvidence recorded. Mice, rats, dogs. Useful for ideas, not proof about people.Stored records in C. elegans (roundworm), 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: Lowers blood pressure by exerting a peripheral vasodilating effect through a direct relaxation of vascular smooth muscle
US prescribing information · 024ac6b8-5ce0-4435-9b11-b1806c511d7b · read 2026-08-28
Heart: The peripheral vasodilating effect is accompanied by an increased heart rate, stroke volume and cardiac output
US prescribing information · 024ac6b8-5ce0-4435-9b11-b1806c511d7b · read 2026-08-28
Kidneys: Usually increases renin activity in plasma, presumably as a result of increased secretion of renin by the renal juxtaglomerular cells in response to reflex sympathetic discharge
US prescribing information · 024ac6b8-5ce0-4435-9b11-b1806c511d7b · read 2026-08-28
Start
Hydralazine
What a person takes: Oral tablet, and intramuscular or intravenous injection for urgent reduction of severe hypertension; also available as a fixed-dose oral combination with isosorbide dinitrate.
The measurement behind this step
Rapidly absorbed after oral administration with peak plasma levels at 1 to 2 hours and an apparent plasma half-life of 3 to 7 hours. Clearance runs through polymorphic N-acetylation, so slow acetylators generally reach higher plasma levels and require lower doses — the same tablet is a materially different exposure in different people. The injectable route exists because the drug is one of the few antihypertensives that can be given parenterally to bring a dangerously high pressure down quickly, which is the setting in which its comparative record against labetalol and nifedipine has been questioned.
Getting in
A phthalazine with a hydrazine group hanging off it
The molecule is small and simple, and the reactive hydrazine group on it is both the reason it works and the reason it causes trouble.
╌╌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
A 1-hydrazinophthalazine. The free hydrazine condenses with aldehydes, which explains both the pyridoxal phosphate interaction behind its peripheral neuritis and the excipient incompatibilities that constrain its formulation. Oral absorption is rapid with peak levels at 1 to 2 hours and an apparent half-life of 3 to 7 hours.
The body disposes of hydralazine by tagging it with an acetyl group, and people do that at very different speeds. Slow acetylators end up with more drug from the same tablet.
──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
The label states that hydralazine is subject to polymorphic acetylation and that slow acetylators generally have higher plasma levels and require lower doses to maintain control of blood pressure. NAT2 genotype is the determinant, and slow acetylation is also the best-established risk factor for the lupus-like syndrome.
It relaxes arteriolar muscle, by a route nobody has pinned down
It makes the muscle around small arteries let go. The prescribing information says the precise mechanism is not fully understood and points vaguely at calcium handling.
╌╌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
The label states that hydralazine apparently lowers blood pressure by direct relaxation of vascular smooth muscle, and that by altering cellular calcium metabolism it interferes with the calcium movements responsible for initiating or maintaining the contractile state. No receptor, channel or enzyme is named.
Because it opens arteries and leaves veins alone, blood pressure falls without the dizziness on standing that other vasodilators cause — but the heart ends up pumping more.
╌╌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
Decreased arterial pressure, diastolic more than systolic, and decreased peripheral vascular resistance, with increased heart rate, stroke volume and cardiac output. Preferential arteriolar dilatation minimises postural hypotension and promotes the rise in output. Renal and cerebral blood flow are maintained or increased.
The heart speeds up and the kidney retains salt, both of which raise the pressure again. That is why the drug is given with a beta-blocker and a diuretic, or with a nitrate.
──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
Plasma renin activity usually rises through reflex sympathetic discharge, generating angiotensin II, aldosterone stimulation and sodium reabsorption. The label describes the resulting state as a hyperdynamic circulation, and warns it can accentuate specific cardiovascular inadequacies.
Paired with isosorbide dinitrate, which supplies the vein dilatation hydralazine does not, it produced one of the clearest survival results in heart failure.
──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
A-HeFT: all-cause mortality 6.2% against 10.2%, p=0.02, hazard ratio 0.57 (p=0.01); heart failure hospitalisation 16.4% against 22.4%, p=0.001, in 1,050 patients on standard therapy including neurohormonal blockers, with the trial stopped early. V-HeFT II, by contrast, found the same combination inferior to enalapril: two-year mortality 25% against 18%, p=0.016.
No suggested links are held for this record, so nothing is hidden from this path.
What we know
The record describes 6 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.
No registered study measured anything of this kind.
Measured
Things only a test, a scale or a device shows.
decrease in supine systolic blood pressure
achieving blood pressure goals
maximum concentration as measured by pk sampling
cerebral blood flow
Meaningful
Things that change how a life goes, not only a number.
combined death and disability
all cause hospitalization or all cause mortality
all cause mortality
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 (14)
peak oxygen uptake during exercise
ocular safety
efficacy
medication recommended by acog for severe hypertension
onset of immediate postoperative delirium in adult
elimination rate constant as measured by pk sampling
half life as measured by pk sampling
absorption rate constant as measured by pk sampling
auc as measured by pk sampling
drug doses
enrollment rate
treatment allocation change
recovery from heartlogic alert
treatment efficacy
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. 3 to 7 hours hours
Read from the label, which states: “HydrALAZINE is rapidly absorbed after oral administration, and peak plasma levels are reached at 1 to 2 hours. Plasma levels of apparent hydrALAZINE decline with a half-life of 3 to 7 hours. Binding to human plasma protein is 87%.”
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.
Adults with hypertension not controlled by other agents, patients needing urgent parenteral blood pressure reduction, and — in the fixed combination — black patients with heart failure. Not people with coronary artery disease or mitral valvular rheumatic heart disease, in whom it is contraindicated.
Who is missing from the studies
Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
What the label states about particular groups
On pediatric, the label states: “Safety and effectiveness in pediatric patients have not been established in controlled clinical trials, although there is experience with the use of hydrALAZINE in pediatric patients.”
US prescribing information · 3b61d1b0-c699-67a8-e054-00144ff88e88 · read 2026-08-30
On people who are pregnant, the label states: “Category C: Animal studies indicate that hydrALAZINE is teratogenic in mice at 20 to 30 times the maximum daily human dose of 200 to 300 mg and possibly in rabbits at 10 to 15 times the maximum daily human dose, but that it is nonteratogenic in rats.”
US prescribing information · 3b61d1b0-c699-67a8-e054-00144ff88e88 · read 2026-08-30
On people who are breastfeeding, the label states: “It is not known whether this drug is excreted in human milk.”
US prescribing information · 3b61d1b0-c699-67a8-e054-00144ff88e88 · read 2026-08-30
Where the result stopped carrying
V-HeFT II: the combination was inferior to enalapril on two-year mortality
The pregnancy meta-analysis found worse maternal and fetal outcomes on almost every measure examined
Monotherapy is undermined by the drug’s own reflex tachycardia, renin rise and sodium retention
Coronary artery disease and mitral valvular rheumatic heart disease are contraindications, and the label states the drug has been implicated in causing myocardial infarction
Drug-induced lupus with glomerulonephritis, whose residua the label says have been detected many years after discontinuation
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, and intramuscular or intravenous injection for urgent reduction of severe hypertension; also available as a fixed-dose oral combination with isosorbide dinitrate
✎ 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
Rapidly absorbed after oral administration with peak plasma levels at 1 to 2 hours and an apparent plasma half-life of 3 to 7 hours. Clearance runs through polymorphic N-acetylation, so slow acetylators generally reach higher plasma levels and require lower doses — the same tablet is a materially different exposure in different people.
✎ 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. The rest of the recorded wording: The injectable route exists because the drug is one of the few antihypertensives that can be given parenterally to bring a dangerously high pressure down quickly, which is the setting in which its comparative record against labetalol and nifedipine has been questioned.
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.
The recorded stepping schedule
What follows is the schedule printed on the label, recorded as it is written there. It is a record of what was done, not a recommendation.
US prescribing information · 024ac6b8-5ce0-4435-9b11-b1806c511d7b · read 2026-08-28
First 2 to 4 days: 10 mg four times daily — The label records that therapy is initiated in gradually increasing dosages, adjusted according to individual response
US prescribing information · 024ac6b8-5ce0-4435-9b11-b1806c511d7b · read 2026-08-28
Balance of the first week: 25 mg four times daily
US prescribing information · 024ac6b8-5ce0-4435-9b11-b1806c511d7b · read 2026-08-28
Second and subsequent weeks: 50 mg four times daily
US prescribing information · 024ac6b8-5ce0-4435-9b11-b1806c511d7b · read 2026-08-28
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
Contraindicated in hypersensitivity to hydralazine, in coronary artery disease, and in mitral valvular rheumatic heart disease. It may produce a clinical picture simulating systemic lupus erythematosus including glomerulonephritis; symptoms usually regress on discontinuation but residua have been detected many years later and long-term steroid treatment may be necessary. Complete blood counts and antinuclear antibody titres are indicated before and periodically during prolonged therapy even in asymptomatic patients. Myocardial stimulation can cause anginal attacks and ischaemic ECG changes, and the drug has been implicated in the production of myocardial infarction. The hyperdynamic circulation it produces may raise pulmonary artery pressure in mitral valve disease and may accentuate other cardiovascular inadequacies. Postural hypotension can occur but is less common than with ganglionic blockers. Caution is directed in cerebrovascular accident and in advanced renal damage. Peripheral neuritis with paraesthesia, numbness and tingling has been observed, attributed to an antipyridoxine effect, and the label directs adding pyridoxine if symptoms develop.
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.
Hydralazine appears in spontaneous reports to regulators. Across the 10 most-reported reaction terms, 1417 reaction mentions were counted. One report can name several reactions.
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, and intramuscular or intravenous injection for urgent reduction of severe hypertension; also available as a fixed-dose oral combination with isosorbide dinitrate
✎ 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
Clearance runs through polymorphic N-acetylation, so slow acetylators generally reach higher plasma levels and require lower doses — the same tablet is a materially different exposure in different people.
✎ 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. The rest of the recorded wording: The injectable route exists because the drug is one of the few antihypertensives that can be given parenterally to bring a dangerously high pressure down quickly, which is the setting in which its comparative record against labetalol and nifedipine has been questioned.
No source is stored against this line.
What is recorded as being sold
178 products list this as an active ingredient in the United States drug directory. 172 of them contain it and nothing else.
FDA National Drug Code directory · 71335-9722 · read 2026-08-29
They are sold as injection, injection, solution, powder, tablet and tablet, film coated, taken intramuscular, intravenous and oral.
FDA National Drug Code directory · 71335-9722 · read 2026-08-29
The regulator's established pharmacologic class for it is arteriolar vasodilation [pe] and arteriolar vasodilator [epc].
FDA National Drug Code directory · 71335-9722 · read 2026-08-29
106 published labels name it as an active ingredient. 100 of them describe this substance alone, which is where its own label text on this page comes from.
US prescribing information · 3b61d1b0-c699-67a8-e054-00144ff88e88 · read 2026-08-29
Those labels are classed as human prescription drug.
US prescribing information · 3b61d1b0-c699-67a8-e054-00144ff88e88 · read 2026-08-29
1 marketed supplement label lists this ingredient, classed as other combinations.
Those labels carry all other, nutrient and structure/function claims. A claim of that kind is written by the manufacturer and is not assessed by any regulator, so its presence says nothing about whether it is true.
Hydralazine Hydrochloride is tablets, usp at 25 mg (the only strength this repackager label supplies), recorded as prescription product; fda label in effect 2025-07-01 in the United States.
US prescribing information · 024ac6b8-5ce0-4435-9b11-b1806c511d7b · read 2026-08-28
Recorded price in US: 0.02709–0.07458 USD per one unit as the pricing file counts it — a tablet, capsule, patch or single item, across 70 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.
RNAWiki could not confidently classify this substance, so no self-experiment plan is offered.
Questions worth asking
Which of the trials of Hydralazine 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 hydralazine alone carries the A-HeFT survival benefit, when the trial tested a fixed combination with a nitrate
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 benefit is specific to self-identified black patients, an inference from retrospective subgroups of 128 and 215 participants in trials the combination did not win overall
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 vasodilator mechanism is understood, when the label names no molecular target and calls the precise mechanism not fully understood
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 hydralazine is the appropriate first choice for severe hypertension in pregnancy, which its own comparative meta-analysis does not support
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 Hydralazine 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.
It causes a lupus-like illness that can outlast the drug by years
In plain words
Hydralazine can produce something that looks like systemic lupus, including kidney inflammation. Stopping usually helps, but the label says traces have been found many years later and steroids may be needed long term.
What was measured
Labelled drug-induced lupus warning including glomerulonephritis and persistence of residua, with the accompanying antinuclear antibody monitoring requirement
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
The Warnings section reads: "In a few patients hydrALAZINE may produce a clinical picture simulating systemic lupus erythematosus including glomerulonephritis. In such patients hydrALAZINE should be discontinued unless the benefit-to-risk determination requires continued antihypertensive therapy with this drug. Symptoms and signs usually regress when the drug is discontinued but residua have been detected many years later. Long-term treatment with steroids may be necessary." The Precautions section adds that complete blood counts and antinuclear antibody titre determinations are indicated before and periodically during prolonged therapy even though the patient is asymptomatic, and that a positive titre requires the physician to weigh the results carefully against the benefits of continuing. Two label facts connect to make this predictable rather than random: hydralazine is subject to polymorphic acetylation, and slow acetylators generally have higher plasma levels and require lower doses. The people who accumulate the drug are the people most likely to develop the syndrome. Very few antihypertensives require routine autoantibody surveillance in patients with no symptoms; this one does.
Source
Hydralazine hydrochloride tablets United States prescribing information, Warnings, Precautions (Laboratory Tests) and Clinical Pharmacology
Role in the trial
Not matched to a registered study
Identity check
no open identity hold
Audit mark
caution
Review state
Written into the record, not signed off as a reviewed claim
A cardiovascular drug contraindicated in coronary artery disease
In plain words
Hydralazine is contraindicated in coronary artery disease, and the label states the drug has been implicated in causing heart attacks. That is an unusual sentence to find on a blood pressure medicine.
What was measured
Labelled contraindications and the stated haemodynamic mechanism producing angina, ischaemic ECG change and reported infarction
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
The Contraindications section lists hypersensitivity to hydralazine, coronary artery disease, and mitral valvular rheumatic heart disease. The Precautions section explains why: "Myocardial stimulation produced by hydrALAZINE can cause anginal attacks and ECG changes of myocardial ischemia. The drug has been implicated in the production of myocardial infarction. It must, therefore, be used with caution in patients with suspected coronary artery disease." The mechanism is the drug’s own haemodynamic signature. It dilates arterioles far more than veins, so blood pressure falls while cardiac output, stroke volume and heart rate all rise — the label’s own word for the resulting state is "hyperdynamic". A faster, harder-working heart in a narrowed coronary bed is precisely the physiology of demand ischaemia. The same hyperdynamic response is why the label warns it may raise pulmonary artery pressure in mitral valve disease.
Source
Hydralazine hydrochloride tablets United States prescribing information, Contraindications, Precautions (General) and Clinical Pharmacology
Role in the trial
Not matched to a registered study
Identity check
no open identity hold
Audit mark
caution
Review state
Written into the record, not signed off as a reviewed claim
A-HeFT: with a nitrate, a 43% reduction in death
In plain words
Paired with isosorbide dinitrate in a single tablet and given to a thousand black patients with advanced heart failure, hydralazine helped cut deaths from about ten per cent to about six, and the trial was stopped early.
What was measured
All-cause mortality and heart failure hospitalisation in 1,050 black patients with advanced heart failure
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
A-HeFT randomised 1,050 black patients with NYHA class III or IV heart failure and dilated ventricles to a fixed dose of isosorbide dinitrate plus hydralazine or placebo on top of standard therapy including neurohormonal blockers. The trial was terminated early because mortality was significantly higher on placebo: 10.2% against 6.2%, p=0.02, a hazard ratio of 0.57 for death from any cause (p=0.01). First hospitalisation for heart failure fell from 22.4% to 16.4%, p=0.001, and quality of life improved (p=0.02). This is a placebo-controlled mortality result on top of modern background therapy and it is the strongest evidence hydralazine has ever produced. It is worth being precise about what it establishes: the trial tested the combination, not hydralazine alone, and it enrolled only black patients, so it cannot say which molecule carries the effect or whether the effect is confined to the group studied.
Written into the record, not signed off as a reviewed claim
V-HeFT II: it lost to an ACE inhibitor, and the race split came afterwards
In plain words
Compared head to head against enalapril in eight hundred men with heart failure, the hydralazine-nitrate combination was worse: 25% died within two years against 18% on enalapril.
What was measured
Two-year mortality with hydralazine plus isosorbide dinitrate against enalapril in 804 men with chronic heart failure
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
V-HeFT II randomised 804 men on digoxin and diuretics to enalapril 20 mg daily or hydralazine 300 mg plus isosorbide dinitrate 160 mg daily. Two-year mortality was 18% on enalapril against 25% on the combination, p=0.016, a 28% relative reduction favouring enalapril, with overall mortality also tending lower (p=0.08). The advantage came from fewer sudden deaths and was more prominent in less symptomatic patients. The combination was not useless — peak exercise oxygen consumption increased only in that arm (p<0.05) and ejection fraction rose more in the first 13 weeks — but on the endpoint that matters it lost. The BiDil label then reports that retrospective analysis located the enalapril advantage in the 574 white participants, with essentially no difference among the 215 black participants, and states that this, together with a similar retrospective finding in V-HeFT I, is the basis on which a third trial was conducted among black patients. So the racial restriction on the modern indication traces back to subgroup analyses of a trial the combination lost overall.
Written into the record, not signed off as a reviewed claim
In severe hypertension of pregnancy, the default drug came off worse than the alternatives
In plain words
Hydralazine was for decades the standard injection for dangerously high blood pressure in pregnancy. A meta-analysis of twenty-one randomised trials found more low blood pressure, more caesareans, more placental separation and worse newborn scores compared with the alternatives.
What was measured
Pooled relative risks for maternal and fetal outcomes with hydralazine against other short-acting antihypertensives across 21 randomised trials in 893 women
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Magee and colleagues pooled 21 randomised trials in 893 women comparing hydralazine with other short-acting antihypertensives for severe hypertension in pregnancy — eight against nifedipine, five against labetalol. Hydralazine was associated with more maternal hypotension (relative risk 3.29, 95% CI 1.50 to 7.23, 13 trials); more caesarean sections (1.30, 1.08 to 1.59, 14 trials); more placental abruption (4.17, 1.19 to 14.28, five trials); more maternal oliguria (4.00, 1.22 to 12.50, three trials); more adverse effects on fetal heart rate (2.04, 1.32 to 3.16, 12 trials); more low one-minute Apgar scores (2.70, 1.27 to 5.88, three trials); and more maternal side effects (1.50, 1.16 to 1.94, 12 trials). Against labetalol there was a trend towards less persistent severe hypertension and less neonatal bradycardia. The authors are careful and their caution belongs in the record: the results are not robust enough to guide clinical practice, there was significant heterogeneity and differences in methodological quality, and adequately powered trials are needed. What they do say is that the data do not support hydralazine as first-line treatment for severe hypertension in pregnancy — a conclusion about the drug’s longest-standing role, drawn from its own comparative trials.
Written into the record, not signed off as a reviewed claim
Seventy years on, the mechanism is still not fully understood
In plain words
The prescribing information opens its pharmacology section by saying the precise mechanism of action is not fully understood, and then offers a description of what happens rather than an explanation of why.
What was measured
That hydralazine’s vasodilator action is understood well enough to attribute to a defined molecular target, when the label names none and calls the precise mechanism not fully understood
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The Clinical Pharmacology section begins: "Although the precise mechanism of action of hydrALAZINE is not fully understood, the major effects are on the cardiovascular system. HydrALAZINE apparently lowers blood pressure by exerting a peripheral vasodilating effect through a direct relaxation of vascular smooth muscle. HydrALAZINE, by altering cellular calcium metabolism, interferes with the calcium movements within the vascular smooth muscle that are responsible for initiating or maintaining the contractile state." Note the two hedges — "apparently" and "not fully understood" — and note that no receptor, channel or enzyme is named. This matters practically rather than academically. Without a molecular target there is no rational way to separate the wanted arteriolar dilatation from the unwanted hyperdynamic response, no structural handle for making a better version, and no mechanistic account of why a hydrazine group produces both vasodilatation and an autoimmune syndrome. The drug has been prescribed since 1953 and remains, in mechanistic terms, a description.
Source
Hydralazine hydrochloride tablets United States prescribing information, Clinical Pharmacology
Role in the trial
Not matched to a registered study
Identity check
no open identity hold
Audit mark
contested
Review state
Written into the record, not signed off as a reviewed claim
The body fights the drug, which is why it is almost never given alone
In plain words
Opening the arteries makes the heart speed up and the kidney hold on to salt. Both reflexes push the blood pressure back up, so hydralazine is normally paired with a drug that slows the heart and a drug that removes salt.
What was measured
Labelled haemodynamic and neurohormonal response to hydralazine: cardiac output, heart rate, plasma renin activity, aldosterone and sodium reabsorption
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The label documents the compensatory cascade in sequence. Peripheral vasodilatation decreases arterial pressure — diastolic more than systolic — and peripheral vascular resistance, while increasing heart rate, stroke volume and cardiac output. Preferential dilatation of arterioles compared with veins minimises postural hypotension and promotes the rise in cardiac output. Plasma renin activity usually increases, presumed to follow from increased renin secretion by juxtaglomerular cells in response to reflex sympathetic discharge; the resulting angiotensin II stimulates aldosterone and consequent sodium reabsorption. So the drug provokes both arms of the response that modern antihypertensive therapy is designed to block. The clinical consequence is that hydralazine monotherapy tends to lose effect, and that its practical use is as a third agent alongside a beta-blocker and a diuretic — or, in heart failure, alongside a nitrate that supplies the venodilatation hydralazine does not.
Source
Hydralazine hydrochloride tablets United States prescribing information, Clinical Pharmacology
Role in the trial
Not matched to a registered study
Identity check
no open identity hold
Audit mark
verified
Review state
Written into the record, not signed off as a reviewed claim
How many documents were read
100 documents were read for this substance.
RNAWiki source record
76 of them state the same halfLife, and they agree.
RNAWiki source record
Where else this substance is registered
FDA substance identifier (UNII)
FD171B778Y
CAS registry number
86-54-4
PubChem compound
3637
RxNorm concept
5470
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 unclear◇Read 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
128 approved applications cover products containing this substance. The earliest was NDA008303, approved 19530115 to NOVARTIS.
This order is fixed in code and does not count clicks or time on the page.
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 direct arteriolar vasodilator whose label states after seventy years that "the precise mechanism of action of hydrALAZINE is not fully understood", which is contraindicated in coronary artery disease and "has been implicated in the production of myocardial infarction", whose lupus-like reaction can leave residua detectable many years after withdrawal — and which, paired with isosorbide dinitrate, cut all-cause mortality from 10.2% to 6.2% in A-HeFT and lost to enalapril in V-HeFT II (two-year mortality 25% against 18%, p=0.016).
Recorded evidence blocks (13)
Q1
What did Hydralazine's largest trial (22213 people) and its longest (16 years) measure?
22213 people in Hydralazine's largest registered study, 16 years in its longest registered window, measuring All-Cause-Hospitalization or All-Cause Mortality. ClinicalTrials.gov · 2026-09-01
9 phase2, 8 phase3, 7 na, 6 phase1, 3 na or unstated, 3 phase4, 1 early phase1; NCT00223717; 2017-01. Last human test completed 2026, NCT04842552.
Interpretation These counts include studies where Hydralazine 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
phase2
9
phase3
8
na
7
phase1
6
na or unstated
3
phase4
3
2 more recorded rows
early phase1
1
Last recorded human testNCT04842552
2026-03-05
recorded 2026-09-01 · last checked 2026-09-04
Q2
From C. elegans to human: where has Hydralazine shown lifespan?
terminated; "Study has been terminated due to poor accrual."
NCT01601483
terminated; "Unmasked without Sponsor's prior knowledge or authorization by the PI."
NCT02933593
withdrawn; "PI withdrew the protocol"
recorded 2026-09-01 · last checked 2026-09-04
Q4
Mouse studies of Hydralazine used 30 ppm — over how long?
Mouse studies of Hydralazine used "30 ppm". clinicaltrials.gov+jax-mpd-itp · 2026-09-04
3 recorded entries; mouse, human; also "Hydralazine hydrochloride 25mg tablets"
Show the evidence
mouse
Hydralazine C2020
30 ppm
Hydralazine C2020
30 ppm
humanNCT04842552
Hydralazine hydrochloride 25mg tablets
recorded 2026-09-04 · last checked 2026-09-04
Q5
Hydralazine's half-life is 3 to 7 hours — which schedules were studied?
3 to 7 hours, the half-life Hydralazine's label states. openfda-label · d2d98842-ff32-4a61-94e0-60e06919948f · 2026-08-28
Show the evidence
half life
3 to 7 hours hours; HydrALAZINE is rapidly absorbed after oral administration, and peak plasma levels are reached at 1 to 2 hours. Plasma levels of apparent hydrALAZINE decline with a half-life of 3 to 7 hours. Binding to human plasma protein is 87%.
metabolism
HydrALAZINE, by altering cellular calcium metabolism, interferes with the calcium movements within the vascular smooth muscle that are responsible for initiating or maintaining the contractile state.
recorded 2026-08-28 · last checked 2026-09-04
Q6
Could one person measure Hydralazine's effect on decrease in supine systolic blood pressure?
Decrease in supine systolic blood pressure: measured in Hydralazine's trials.
Interpretation decrease in supine systolic blood pressure is the recorded endpoint.
Show the evidence
biomarkers
decrease in supine systolic blood pressure; 2026-09-01
peak oxygen uptake during exercise; 2026-09-01
achieving blood pressure goals; 2026-09-01
ocular safety; 2026-09-01
combined death and disability; 2026-09-01
efficacy; 2026-09-01
14 more recorded rows
biomarkers
medication recommended by acog for severe hypertension; 2026-09-01
biomarkers
onset of immediate postoperative delirium in adult; 2026-09-01
biomarkers
elimination rate constant as measured by pk sampling; 2026-09-01
biomarkers
half life as measured by pk sampling; 2026-09-01
biomarkers
absorption rate constant as measured by pk sampling; 2026-09-01
biomarkers
auc as measured by pk sampling; 2026-09-01
biomarkers
maximum concentration as measured by pk sampling; 2026-09-01
biomarkers
drug doses; 2026-09-01
biomarkers
all cause hospitalization or all cause mortality; 2026-09-01
biomarkers
all cause mortality; 2026-09-01
biomarkers
enrollment rate; 2026-09-01
biomarkers
treatment allocation change; 2026-09-01
biomarkers
recovery from heartlogic alert; 2026-09-01
biomarkers
cerebral blood flow; 2026-09-01
half life
2026-09-04; halfLife; hours; 3 to 7 hours; 2026-08-28
human trials at or under30
10
smallest human trial
0; NCT00575640; PHASE1/PHASE2; the smallest recorded human enrolment at or below 30; the registry states no direction of its result; WITHDRAWN
Q7
Which of absorption rate constant as measured by pk sampling, achieving blood pressure goals and all cause hospitalization or all cause mortality did Hydralazine's trials measure?
absorption rate constant as measured by pk sampling, achieving blood pressure goals and all cause hospitalization or all cause mortality lead 21 outcome terms across Hydralazine's trials. ClinicalTrials.gov · 2026-09-01
Interpretation ocular safety, combined death and disability, efficacy, medication recommended by acog for severe hypertension, onset of immediate postoperative delirium in adult and elimination rate constant as measured by pk sampling follow.
Show the evidence
decrease in supine systolic blood pressure
1
peak oxygen uptake during exercise
1
achieving blood pressure goals
1
ocular safety
1
combined death and disability
1
efficacy
1
14 more recorded rows
medication recommended by acog for severe hypertension
1
onset of immediate postoperative delirium in adult
1
elimination rate constant as measured by pk sampling
1
half life as measured by pk sampling
1
absorption rate constant as measured by pk sampling
1
auc as measured by pk sampling
1
maximum concentration as measured by pk sampling
1
drug doses
1
all cause hospitalization or all cause mortality
1
all cause mortality
1
enrollment rate
1
treatment allocation change
1
recovery from heartlogic alert
1
cerebral blood flow
1
recorded 2026-09-01 · last checked 2026-09-04
Q8
Which of Hydralazine's 2 ongoing trials reports first?
Clearance (CL) or apparent oral clearance (CL/F) as measured by PK sampling; Number of participants with recovery from HeartLogic Alert; latest 2026-12-31
Show the evidence
Trial
NCT04278404
"Pharmacokinetics, Pharmacodynamics, and Safety Profile of Understudied Drugs Administered to Children Per Standard of Care (POPS)"; n 5000; "Clearance (CL) or apparent oral clearance (CL/F) as measured by PK sampling"; 2026-12
NCT06218199
"Diuretics vs. Afterload Reduction for Treatment of HeartLogic Alerts"; n 80; "Number of participants with recovery from HeartLogic Alert"; 2026-12-31
recorded 2026-09-01 · last checked 2026-09-04
Q9
Which 14 trials of Hydralazine posted no result?
Posted no result
14 of 14 completed trials
Registrations
NCT00000499, NCT00226096, NCT00599235, NCT01013376, NCT00996060 and NCT01538875, and 8 more
Completion dates
oldest 1983-05; newest 2023-05-04
Show the evidence
Trial
NCT00000499
1983-05
NCT00226096
2007-09
NCT00599235
2008-08
NCT01013376
2009-08
NCT00996060
2013-01
NCT01538875
2013-05
8 further recorded trials
NCT02050529
2015-03
NCT00223717
2017-01
NCT01422616
2018-08
NCT04435210
2019-02-20
NCT03967496
2019-03-31
NCT03423810
2020-01-30
NCT04467931
2020-12-31
NCT04484350
2023-05-04
Q10
At the median, Hydralazine's trials enrolled 99 people — anything larger?
Median enrolment
99
Largest enrolment
22213
Registered trials counted
31
Q11
What do 1417 spontaneous reports say about Hydralazine — 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.
Hydralazine appears in spontaneous reports to regulators. Across the 10 most-reported reaction terms, 1417 reaction mentions were counted: anti-neutrophil cytoplasmic antibody positive vasculitis 382; acute kidney injury 145; lupus-like syndrome 141; premature baby 134. open-targets-adr · CHEMBL276832 · 2026-06-24
exercise is named in Hydralazine's label sentences: "Hydralazine may mitigate nitrate tolerance, and the ISDN-hydralazine combination in the Vasodilators in Heart Failure Trial (V-HeFT) I improved survival and exercise tolerance in men with dilated cardiomyopathy or HF with reduced ejection fraction, most notably in self-identified black participants." openfda-label+europepmc · 2014-04-18
1 recorded statement; exercise
Show the evidence
exercise
Hydralazine may mitigate nitrate tolerance, and the ISDN-hydralazine combination in the Vasodilators in Heart Failure Trial (V-HeFT) I improved survival and exercise tolerance in men with dilated cardiomyopathy or HF with reduced ejection fraction, most notably in self-identified black participants.
recorded 2014-04-18 · last checked 2026-09-04
Q13
What is recorded about Hydralazine and senolytic?
"The interaction of DNMT1 with ATG7 through its CXXC domain is essential for its degradation, and treatment with senolytics also downregulates DNMT1 in aged organs, supporting two feedback loops between them.<b>Abbreviations</b>: 4-OHT, 4-hydroxytamoxifen; ChIP, chromatinimmunoprecipitation; D, dasatinib; D-gal, D-galactose; DCT/Trp-2,…" — where Hydralazine and senolytic appear together. Europe PMC · pathway abstract search · 2026-05-28
"The interaction of DNMT1 with ATG7 through its CXXC domain is essential for its degradation, and treatment with senolytics also downregulates DNMT1 in aged organs, supporting two feedback loops between them.<b>Abbreviations</b>: 4-OHT, 4-hydroxytamoxifen; ChIP, chromatinimmunoprecipitation; D, dasatinib; D-gal, D-galactose; DCT/Trp-2, dopachrometautomerase; DMRs, differentially methylated…"
sirtuinPMID 31659167
"Using in vitro and in vivo models, we demonstrate a mechanism in which binding and stabilization of a catalytic subunit of PKA by hydralazine lead to improved mitochondrial function and metabolic homeostasis via the SIRT1/SIRT5 axis, which underlies hydralazine's prolongevity and stress resistance benefits."
NAD+
PMID 15076159
"Mice received Ang II alone (400 ng/kg per min, subcutaneously), Ang II + apocynin (NAD(P)H oxidase inhibitor, 2.5 mg/day, in the food), apocynin alone or Ang II + hydralazine (50 mg/kg per day) for 14 days."
PMID 18487445
"Systolic blood pressure rose in DOCA-salt rats and was reduced after 3 wk by apocynin [NAD(P)H oxidase inhibitor and/or radical scavenger], allopurinol (XO inhibitor), bosentan (ET(A/B) receptor antagonist), BMS-182874 (BMS; ET(A) receptor antagonist), and hydralazine."
recorded 2026-05-28 · last checked 2026-09-04
Where it is registeredIdentifiers, relations and other names
Apresoline, Dralzine, Apresoline / Dralzine; as a fixed combination with isosorbide dinitrate, BiDil, HIDRAL
Salt form
Hydralazine hcl, Hydralazine hydrochloride component of apresazide, Hydralazine hydrochloride component of apresoline-esidrix, Hydralazine hydrochloride component of bidil, Hydralazine hydrochloride component of cam-ap-es, Hydralazine hydrochloride component of dralserp, Hydralazine hydrochloride component of hydrap-es, Hydralazine hydrochloride component of hydra-zide, Hydralazine hydrochloride component of -hydrochlorothiazide-reserpine, Hydralazine hydrochloride component of hydroserpine plus (r-h-h), Hydralazine hydrochloride component of ser-a-gen, Hydralazine hydrochloride component of ser-ap-es
Sources (12)
Sources
ClinicalTrials.govClinicalTrials.gov API v2 snapshot 2026-09-01T09:00:05 ·
ChEMBL ATC CC BY-SA · ClinicalTrials.gov — US Government work · Europe PMC — metadata only, under the recorded legal gate · NIA ITP via the JAX Mouse Phenome Database · Open Targets 26.06 — CC0 · derived from this page's own recorded fields; no external licence · mixed register set; per-register licences in docs/specs/corpus-20k-sources.md · openFDA / DailyMed — US Government work
✗ required summary fields resolved: 5 required field(s) not terminal: Why people use it, Best-supported result, Most important common problem, Biggest unanswered question, Human evidence
✓ public claims reviewed: 0 reviewed claim(s); drafts are never rendered
✓ source coverage passed: 12 source rows
✓ no critical contamination: no quarantine open
✓ canonical metadata passed: slug and display name present
✓ no raw internal fields: enforced by the copy-contract test over the rendered page
This is a record of evidence. It is not medical advice, and it does not say this substance suits you. Nothing here says any substance on RNAWiki is appropriate for a child.