This page shows what was measured, who it was measured in, and what that does not settle.
What Tadalafil does in the body
Tadalafil blocks an enzyme that breaks down a signalling molecule called cyclic GMP.
With the enzyme blocked, cyclic GMP accumulates and smooth muscle relaxes — which is a well-understood account of how the drug produces an erection. For prostate symptoms, the mechanism is unknown: the label says it has not been established. The leading explanations are that tadalafil relaxes prostate and bladder-neck muscle through the same pathway, improves blood flow to the pelvis, or quietens sensory nerves in the bladder. The trials are positive; the explanation is not settled.
Why people take it. An enlarged prostate causing a weak stream and frequent urination — and, in the same tablet, erectile dysfunction
What happened in people
IIEF erectile function domain improved 4.0 points on tadalafil (p<0.001) and -0.4 on tamsulosin (p=0.699)
✎ 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.
Tadalafil once daily for 12 weeks in men with signs and symptoms of benign prostatic hyperplasia, with a tamsulosin active control (NCT00970632) · a recorded source, not a stored snapshot
The only drug in this group that treats lower urinary tract symptoms and erectile dysfunction in one tablet, which is why it is chosen where both are present
Where it acts
Smooth muscle of the prostate, bladder and the blood vessels supplying both, where cyclic GMP signalling is amplified rather than a receptor being blocked
Kind of result
What a body can do day to day
Supervision
RNAWiki has not recorded a supervision or regulatory status for this substance.
What the registries record it as
Its recorded molecular formula is C22H19N3O4, weighing 389.41.
US prescribing information · dc0a6a03-5ef1-4507-b888-5b559653c3e9 · 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 126 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
Blood sugar
∅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 moved5 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.
Endurance
∅Nothing in the sources checkedNo registered study lists a life outcome for this goal.
…Waiting for a reviewer3 registered performance measure of this kind.
∅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.
Healthy ageing
…Waiting for a reviewer1 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.
Which registered measures put each goal on this table
Blood sugar
insulin sensitivity; fasting glucose; postprandial glucose; first phase of insulin secretion; total insulin secretion
Endurance
6 minute walking distance; 6 minute walk distance; six minute walk distance in meters
Healthy ageing
all cause mortality
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.
△ Only a number moved
5 registered test measure.
— Not recorded
Harms were not a registered measure for this goal.
… Waiting for a reviewer
Who was studied is listed further down the page.
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.
Change in International Prostate Symptom Score through 12 weeks versus placebo, after a four-week placebo run-in
✓ The study showed what it set out to show
Who was studied
Tadalafil versus tamsulosin versus placebo (NCT00970632)
IPSS versus placebo: tadalafil -2.1 (p=0.001, primary outcome), tamsulosin -1.5 (p=0.023). Peak flow +2.4 mL/s (p=0.009) and +2.2 mL/s (p=0.014). IIEF erectile function +4.0 (p<0.001) and -0.4 (p=0.699)
Repeated elsewhere
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 paper's own limitations note that the study was not powered to compare tadalafil directly against tamsulosin, despite a title asserting that the two "similarly improved" symptoms. The four-week placebo run-in removes part of the placebo response before randomisation.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet, once daily at the low dose for the urinary indication
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
Tadalafil once daily for 12 weeks in men with signs and symptoms of benign prostatic hyperplasia, with a tamsulosin active control (NCT00970632) · a recorded source, not a stored snapshot
Proportion achieving a 3-point or greater, or 25% or greater, improvement in total IPSS at week 12
✓ The study showed what it set out to show
Who was studied
Integrated responder analysis of four placebo-controlled trials (Nickel 2015)
How many people
1499
Study design
Post hoc integrated analysis of four randomised placebo-controlled 12-week studies
Compared against
A dummy treatment
Kind of result
A number that stands in for health
What was found
3-point threshold: 71.1% on tadalafil against 56.0% on placebo, odds ratio 1.9 (95% CI 1.5 to 2.4), P<0.001. 25% threshold: 61.7% against 45.5%, odds ratio 2.0 (1.6 to 2.5), P<0.001
Repeated elsewhere
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 placebo response rate — 56.0% and 45.5% — is the number that does not appear in the paper's conclusion, which reports only that about two-thirds of tadalafil-treated patients achieved a clinically meaningful improvement.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet, once daily at the low dose for the urinary indication
Interval reported. 95% CI 1
Written into the record, not signed off as a reviewed claim.
Tadalafil once daily for 12 weeks in men with signs and symptoms of benign prostatic hyperplasia, with a tamsulosin active control (NCT00970632) · a recorded source, not a stored snapshot
RNAWiki holds 2 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.1 registered measure of this kind. No reviewed result.
■What a body can do day to dayEvidence recorded. Walking, dressing, breathing, recovering.5 registered measures of this kind.
■Measured performanceEvidence recorded. How much was lifted, how far was run, how fast.5 registered measures of this kind.
■Symptoms and quality of lifeEvidence recorded. Pain, tiredness, mood, sleep, as the person rated it.2 registered measures of this kind.
■A number that stands in for healthEvidence recorded. Cholesterol, blood sugar, bone density. A stand-in, not the thing itself.10 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 Mouse, Rat. 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
Pelvic and reproductive organs: PDE5 inhibition increases cGMP, causing smooth muscle relaxation and increased blood flow into the corpus cavernosum
US prescribing information · 00cbc656-768d-4995-bb6d-a0d4b32a248c · read 2026-08-27
Bladder and urinary tract: The effect of PDE5 inhibition on cGMP is also observed in the smooth muscle of the prostate, the bladder and their vascular supply
US prescribing information · 00cbc656-768d-4995-bb6d-a0d4b32a248c · read 2026-08-27
Start
Tadalafil
What a person takes: Oral tablet, once daily at the low dose for the urinary indication.
The measurement behind this step
A conventional film-coated tablet taken once daily with or without food. The urinary indication uses a low daily dose rather than the as-needed dosing familiar from the erectile indication, and the same molecule is sold at a different dose under a different name for pulmonary arterial hypertension. The label limits combination with finasteride at initiation to 26 weeks.
Getting in
A low daily dose rather than an as-needed one
For the prostate indication the tablet is taken every day at a low dose, not before sex. The drug stays in the body far longer than others of its kind, which is what makes a daily schedule work.
╌╌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
Oral tablet, 5 mg once daily for the urinary indication. The long half-life relative to other PDE5 inhibitors follows from the rigid beta-carboline diketopiperazine geometry rather than from any formulation step. Cleared predominantly by CYP3A4, so strong inhibitors raise exposure.
Tadalafil once daily for 12 weeks in men with signs and symptoms of benign prostatic hyperplasia, with a tamsulosin active control (NCT00970632) · a recorded source, not a stored snapshot
It has to enter the cell, because the target is an enzyme inside it
Phosphodiesterase works inside the cell, not on its surface. The drug has to cross the cell membrane to reach it, which is different from most of the drugs used for this condition.
╌╌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
PDE5 is a cytosolic enzyme, so passive membrane permeation is required — unlike the alpha-1 and muscarinic antagonists in this file, whose targets face the extracellular space. This is the same structural situation as finasteride, and it is why both drugs need a genuine cell-entry step in any assay panel.
Tadalafil once daily for 12 weeks in men with signs and symptoms of benign prostatic hyperplasia, with a tamsulosin active control (NCT00970632) · a recorded source, not a stored snapshot
It stops cyclic GMP from being destroyed rather than blocking a receptor
Most drugs here block a signal. This one protects a signal: it stops the enzyme that clears away a relaxation messenger, so the messenger accumulates.
╌╌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
Competitive inhibition of PDE5 prevents hydrolysis of cyclic GMP, so nitric-oxide-driven cyclic GMP signalling is amplified rather than initiated. The distinction matters clinically: the drug depends on endogenous nitric oxide release to have anything to amplify, which is also the reason exogenous nitrates are an absolute contraindication rather than a caution.
Tadalafil once daily for 12 weeks in men with signs and symptoms of benign prostatic hyperplasia, with a tamsulosin active control (NCT00970632) · a recorded source, not a stored snapshot
Smooth muscle relaxes — and for the prostate, the label stops there
Accumulated cyclic GMP relaxes smooth muscle, which explains the erectile effect completely. For the urinary effect, the prescribing information says the mechanism has not been established.
╌╌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
Cyclic GMP activates protein kinase G, which lowers intracellular calcium and desensitises the contractile apparatus, relaxing smooth muscle. Whether the urinary benefit arises from that relaxation in prostatic and bladder-neck muscle, from increased pelvic perfusion, or from reduced bladder afferent activity, the label declines to say. The trials are positive and the explanation is open.
Tadalafil once daily for 12 weeks in men with signs and symptoms of benign prostatic hyperplasia, with a tamsulosin active control (NCT00970632) · a recorded source, not a stored snapshot
Two points of symptom score, 2.4 mL/sec of flow, and four points of erectile function
The symptom score improves by about two points more than placebo and the flow rate by 2.4 millilitres a second — much like an alpha-blocker. What is different is that erectile function improves by four points where the alpha-blocker managed nothing.
╌╌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
IPSS -2.1 against placebo (p=0.001) versus tamsulosin -1.5 (p=0.023); peak flow +2.4 mL/s (p=0.009) versus +2.2 (p=0.014); IIEF erectile function +4.0 (p<0.001) versus -0.4 (p=0.699). In a pooled responder analysis, 71.1% reached a 3-point IPSS improvement against 56.0% on placebo, odds ratio 1.9 (95% CI 1.5 to 2.4).
Tadalafil once daily for 12 weeks in men with signs and symptoms of benign prostatic hyperplasia, with a tamsulosin active control (NCT00970632) · a recorded source, not a stored snapshot
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.
total international prostate symptom at week 12 endpoint
total international prostate symptom at week 12
Measured
Things only a test, a scale or a device shows.
insulin sensitivity
time to reach maximum observed plasma concentration
trough plasma concentrations
maximum observed plasma concentration
urinary sodium excretion
pharmacokinetics maximum drug concentration of ly2623091
fasting glucose
postprandial glucose
first phase of insulin secretion
total insulin secretion
Meaningful
Things that change how a life goes, not only a number.
6 min walking test
6 minute walking distance
all cause mortality
6 minute walk distance
6 minute walk test
six minute walk distance in meters
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 (22)
visual persistence
reaction time
recurrent priapism frequency
choice of treatment for use in the extension phase
choice of drug at visit 5
adverse events
beta cell function
pulmonary vascular resistance
time to discontinuation of randomized treatment
area under the curve of the 24 hour dosing interval
apparent oral clearance
volume of distribution at steady state
hospitalizations
right ventricular ejection fraction
functional muscle ischemia
response rate
safety
area under curve of dutasteride
cmax of dutasteride
renal function
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. 17.5 hours hours
Read from the label, which states: “Excretion — The mean oral clearance for tadalafil is 2.5 L/hr and the mean terminal half-life is 17.5 hours in healthy subjects.”
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.
Men with lower urinary tract symptoms who also have erectile dysfunction, which is the population in which a single tablet addressing both is genuinely different from the alternatives. In the head-to-head trial, tadalafil improved erectile function by 4.0 points on the IIEF domain and tamsulosin by -0.4.
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 of tadalafil in pediatric patients have not been established.”
US prescribing information · dc0a6a03-5ef1-4507-b888-5b559653c3e9 · read 2026-08-30
On older people, the label states: “Of the total number of subjects in the clinical study of tadalafil for pulmonary arterial hypertension, 28 percent were 65 and over, while 8 percent were 75 and over.”
US prescribing information · dc0a6a03-5ef1-4507-b888-5b559653c3e9 · read 2026-08-30
On people who are pregnant, the label states: “Risk Summary Limited data from case series with tadalafil use in pregnant women have not identified a drug-associated risk of major birth defects, miscarriage or adverse maternal or fetal outcomes.”
US prescribing information · dc0a6a03-5ef1-4507-b888-5b559653c3e9 · read 2026-08-30
On people who are breastfeeding, the label states: “8.3 Females and Males of Reproductive Potential Infertility Males Based on the data from 3 studies in adult males, tadalafil decreased sperm concentrations in the study of 10 mg tadalafil for 6 months and the study of 20 mg tadalafil for 9 months.”
US prescribing information · dc0a6a03-5ef1-4507-b888-5b559653c3e9 · read 2026-08-30
On people with reduced liver function, the label states: “Because of limited clinical experience in patients with mild to moderate hepatic cirrhosis (Child-Pugh Class A or B), consider a starting dose of tadalafil 20 mg once daily.”
US prescribing information · dc0a6a03-5ef1-4507-b888-5b559653c3e9 · read 2026-08-30
On people with reduced kidney function, the label states: “For patients with mild or moderate renal impairment, start tadalafil at 20 mg once daily.”
US prescribing information · dc0a6a03-5ef1-4507-b888-5b559653c3e9 · read 2026-08-30
Where the result stopped carrying
The mechanistic account for this indication, which remains unestablished on the label more than a decade after approval
The combination strategy with alpha-blockers, closed off by additive blood-pressure lowering
Any attempt to read the responder headline as a drug effect — the placebo arm reached the threshold 56% of the time
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
Prescription only
❝ Quoted from a source
Where this came from
Copied from a source RNAWiki stored, with the source named.
Read from the recorded approval status.
No source is stored against this line.
Form and route
Oral tablet, once daily at the low dose for the urinary indication
✎ 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
A conventional film-coated tablet taken once daily with or without food.
✎ 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 urinary indication uses a low daily dose rather than the as-needed dosing familiar from the erectile indication, and the same molecule is sold at a different dose under a different name for pulmonary arterial hypertension. The label limits combination with finasteride at initiation to 26 weeks.
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
Contraindicated absolutely with any organic nitrate and with guanylate cyclase stimulators such as riociguat, because all three act on the same cyclic GMP pathway. Combination with alpha-blockers for benign prostatic hyperplasia is not recommended, because both lower blood pressure. The label warns about sudden vision loss as a possible sign of non-arteritic anterior ischaemic optic neuropathy, with an approximately two-fold increased risk in observational studies, and about sudden hearing loss. Commonest adverse effects are the vasodilatory ones the mechanism predicts: headache, dyspepsia, back pain, flushing and nasal congestion.
Nobody counted how many people took this and were fine, so this cannot be turned into a rate.
Tadalafil once daily for 12 weeks in men with signs and symptoms of benign prostatic hyperplasia, with a tamsulosin active control (NCT00970632) · a recorded source, not a stored snapshot
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.
Tadalafil appears in spontaneous reports to regulators. Across the 10 most-reported reaction terms, 4850 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, once daily at the low dose for the urinary indication
✎ 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
A recorded note compares this form with the others that are sold. It is kept below, word for word.
§ A fixed RNAWiki sentence
Where this came from
Wording RNAWiki always uses, not a finding about this substance.
The recorded note, unchanged: The urinary indication uses a low daily dose rather than the as-needed dosing familiar from the erectile indication, and the same molecule is sold at a different dose under a different name for pulmonary arterial hypertension. The label limits combination with finasteride at initiation to 26 weeks.
No source is stored against this line.
What is recorded as being sold
308 products list this as an active ingredient in the United States drug directory. 303 of them contain it and nothing else.
FDA National Drug Code directory · 71610-728 · read 2026-08-29
They are sold as capsule, granule, powder, suspension, tablet and tablet, coated, taken oral.
FDA National Drug Code directory · 71610-728 · read 2026-08-29
The regulator's established pharmacologic class for it is phosphodiesterase 5 inhibitor [epc] and phosphodiesterase 5 inhibitors [moa].
FDA National Drug Code directory · 71610-728 · read 2026-08-29
143 published labels name it as an active ingredient. 142 of them describe this substance alone, which is where its own label text on this page comes from.
US prescribing information · 36350106-98bc-41fc-bede-8be5e6f54a8a · read 2026-08-29
Those labels are classed as human prescription drug.
US prescribing information · 36350106-98bc-41fc-bede-8be5e6f54a8a · read 2026-08-29
tadalafil is film coated tablets at Tablets: 2.5 mg, 5 mg, 10 mg, 20 mg, recorded as prescription product; fda label in effect 2024-10-16 in the United States.
US prescribing information · 00cbc656-768d-4995-bb6d-a0d4b32a248c · read 2026-08-27
Recorded price in US: 0.10216–0.15815 USD per one unit as the pricing file counts it — a tablet, capsule, patch or single item, across 126 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 Tadalafil 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 tadalafil relieves urinary symptoms by relaxing prostatic smooth muscle — a plausible mechanism the label explicitly declines to assert
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 trial showed tadalafil and tamsulosin to be equivalent — it was not powered to compare them and says so
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 two-thirds of treated men benefit — more than half the placebo group met the same threshold, and the drug-attributable difference is about 15 percentage points
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 a PDE5 inhibitor can be added to an existing alpha-blocker for extra urinary benefit — the label does not recommend that combination for this indication
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 Tadalafil 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.
The label states the mechanism for this indication has not been established
In plain words
Tadalafil is licensed to treat the symptoms of an enlarged prostate. Its own prescribing information says nobody has established how it does that.
What was measured
The mechanism-of-action statement carried on the current US label for the benign prostatic hyperplasia indication
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The Mechanism of Action section describes the erectile indication precisely — inhibition of phosphodiesterase type 5 enhances erectile function by increasing the amount of cyclic GMP — and then states of the urinary indication: "The mechanism for reducing BPH symptoms has not been established." Candidate explanations circulating in the literature include relaxation of prostatic and bladder-neck smooth muscle through nitric oxide and cyclic GMP signalling, increased pelvic and prostatic blood flow, and reduced afferent nerve activity from the bladder; the label commits to none of them. This is a licensed indication supported by randomised placebo-controlled evidence and unsupported by an agreed mechanism, which is an honest position for a regulator to take and an unusual one to find. It also means that every mechanistic explanation a reader encounters for this drug's urinary effect is an inference beyond what the manufacturer will assert.
Source
US prescribing information for tadalafil tablets, Mechanism of Action section (openFDA drug label endpoint)
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
Two points of symptom score over placebo, and a genuine flow-rate improvement
In plain words
In the trial comparing it directly with tamsulosin, tadalafil improved the symptom score by 2.1 points more than placebo and the flow rate by 2.4 millilitres a second. Tamsulosin achieved 1.5 and 2.2.
What was measured
Change in International Prostate Symptom Score and peak urine flow rate against placebo at 12 weeks, tadalafil and tamsulosin
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Oelke and colleagues randomised 511 men aged 45 and over with an IPSS of 13 or more and a peak flow of 4 to 15 mL/s, after a four-week placebo run-in, to placebo (n=172), tadalafil 5 mg (n=171) or tamsulosin 0.4 mg (n=168) for 12 weeks. IPSS improved against placebo by 2.1 points with tadalafil (p=0.001, the primary efficacy outcome) and 1.5 with tamsulosin (p=0.023), with separation as early as week 1 for both (-1.5 each, p<0.01). Peak flow rose 2.4 mL/s with tadalafil (p=0.009) and 2.2 with tamsulosin (p=0.014). The four-week placebo run-in before randomisation is worth noting: it removes the earliest and largest part of the placebo response before the comparison begins, which makes these margins harder-won than they would be without it.
Written into the record, not signed off as a reviewed claim
The trial titled "similarly improved" was not powered to compare the two drugs
In plain words
The paper is called "Monotherapy with tadalafil or tamsulosin similarly improved lower urinary tract symptoms". Its own limitations section says it was not powered to compare tadalafil against tamsulosin.
What was measured
Stated statistical power of the trial for the tadalafil versus tamsulosin comparison
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Both active arms were compared against placebo, and both beat it. The abstract then states: "This study was limited in not being powered to directly compare tadalafil versus tamsulosin." A word like "similarly" in a title is a comparative claim, and a trial that cannot support a comparative claim can support only the two separate placebo comparisons it was designed for. The observed differences run in tadalafil's favour on IPSS (2.1 against 1.5) and are essentially identical on peak flow (2.4 against 2.2), so nothing here is misleading about direction — but "similar" and "not statistically distinguishable in a trial that could not distinguish them" are different statements, and only the second is supported.
Written into the record, not signed off as a reviewed claim
71% of treated men reached the response threshold, and 56% of placebo men did too
In plain words
A pooled analysis of 1,499 patients found about two thirds of tadalafil-treated men achieved a clinically meaningful improvement. More than half the placebo group achieved the same thing.
What was measured
Proportion achieving a 3-point or 25% IPSS improvement at 12 weeks, tadalafil versus placebo, pooled across four trials
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Nickel and colleagues ran a post hoc integrated analysis of four placebo-controlled 12-week studies, 752 patients on tadalafil 5 mg and 747 on placebo, all after a four-week placebo run-in. Using a threshold of a 3-point or greater IPSS improvement, 71.1% of tadalafil patients and 56.0% of placebo patients responded (odds ratio 1.9, 95% CI 1.5 to 2.4, P<0.001). Using a 25% or greater improvement, 61.7% and 45.5% responded (odds ratio 2.0, 95% CI 1.6 to 2.5, P<0.001). The paper's conclusion reports the first of each pair: about two-thirds of tadalafil-treated patients achieve a clinically meaningful improvement. Both numbers are true. Quoted alone, the treated-arm figure attributes to the drug a response that more than half the placebo group also produced, and the difference — 15.1 and 16.2 percentage points — is the part that belongs to it.
Written into the record, not signed off as a reviewed claim
It is the only drug here that improves the urine stream and erectile function at once
In plain words
In the head-to-head trial, erectile function improved by 4.0 points on tadalafil and by -0.4 on tamsulosin. That is the one place the two drugs separate completely.
What was measured
Change in IIEF erectile function domain, IPSS quality-of-life index and treatment satisfaction against placebo, both active arms
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
In the 511-man trial, the International Index of Erectile Function erectile-function domain improved against placebo by 4.0 points with tadalafil (p<0.001) and by -0.4 with tamsulosin (p=0.699). The IPSS Quality-of-Life Index and the Treatment Satisfaction Scale for BPH both improved significantly with tadalafil (both p<0.05) and neither improved with tamsulosin (both p>0.1). Given that the two drugs produced near-identical symptom-score and flow-rate results in the same trial, the quality-of-life and satisfaction separation most plausibly follows from the erectile-function difference rather than from the urinary one — which is an inference, and a straightforward one. Erectile dysfunction and lower urinary tract symptoms coexist in a large fraction of men over 50, and this is the only entry in this file that addresses both with one tablet.
Written into the record, not signed off as a reviewed claim
It cannot be combined with the drug class it is compared against
In plain words
The obvious next question — can you take this and an alpha-blocker together for an enlarged prostate — has an answer on the label, and the answer is no.
What was measured
Label position on combining a PDE5 inhibitor with an alpha-blocker for benign prostatic hyperplasia
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
The label advises caution when PDE5 inhibitors are coadministered with alpha-blockers because of additive blood-pressure lowering, and states that combination use for benign prostatic hyperplasia is not recommended. Both classes relax vascular smooth muscle, so the interaction is mechanistic rather than idiosyncratic. This closes off the combination strategy that MTOPS validated for the other pairing in this indication, where an alpha-blocker plus a 5-alpha-reductase inhibitor reduced clinical progression by 66% against placebo and beat both monotherapies. The pairing the label does contemplate is with finasteride, and it contemplates it with a limit: if tadalafil is used with finasteride to initiate BPH treatment, such use is recommended for up to 26 weeks.
Source
US prescribing information for tadalafil tablets, Warnings and Precautions, Drug Interactions and Indications sections (openFDA drug label endpoint)
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
An absolute nitrate contraindication, and two rare permanent harms on the label
In plain words
Tadalafil must never be taken with any nitrate. The label also warns about sudden loss of vision in one or both eyes and sudden hearing loss, both of which mean stopping the drug and getting help immediately.
What was measured
Contraindicated coadministrations and the reported relative risk of non-arteritic anterior ischaemic optic neuropathy
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The label contraindicates administration to patients using any form of organic nitrate, and to patients taking guanylate cyclase stimulators such as riociguat — both interactions amplifying the same cyclic GMP pathway the drug acts on, so the haemodynamic effect is multiplicative. It describes sudden loss of vision in one or both eyes as a possible sign of non-arteritic anterior ischaemic optic neuropathy, with an approximately two-fold increased risk reported in observational studies, and instructs patients to stop and seek prompt attention for sudden decrease or loss of hearing. A two-fold increase on a rare event remains a rare event, and observational data cannot establish causation. These sit on the label because the outcomes are permanent, not because the evidence is settled — which is the correct reason for a warning and a poor reason for a risk estimate.
Source
US prescribing information for tadalafil tablets, Contraindications and Warnings and Precautions sections (openFDA drug label endpoint)
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 hundred and thirty-seven generic suppliers, and fourteen cents a tablet
In plain words
This was one of the most expensive branded drugs in the world. The acquisition-cost file now lists 137 products for it at a median of fourteen cents a tablet.
What was measured
Median pharmacy acquisition cost per tablet and number of listed products, against the other drugs on the same file
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The CMS National Average Drug Acquisition Cost file effective 19 August 2026 lists tadalafil as generic with 137 products and a median of US$0.1400 per tablet. That is the largest supplier count of any drug in this file — more than tamsulosin's 33, oxybutynin's 92 or finasteride's 50 — and it is the clearest demonstration in this group that price in this market tracks the number of entrants rather than anything about the molecule. Mirabegron, off patent with seventeen listings, sits at US$9.60. Tadalafil, off patent with 137, sits at fourteen cents. The synthesis of a beta-carboline diketopiperazine with two controlled stereocentres is not simpler than that of an extended-release aminothiazole tablet; the market structure is different.
Source
CMS National Average Drug Acquisition Cost file, effective 19 August 2026, as stored on this record
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
141 documents were read for this substance.
RNAWiki source record
Where else this substance is registered
FDA substance identifier (UNII)
742SXX0ICT
CAS registry number
171596-29-5
PubChem compound
110635
RxNorm concept
358263
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
52 approved applications cover products containing this substance. The earliest was NDA021368, approved 20031121 to LILLY.
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 phosphodiesterase type 5 inhibitor licensed for benign prostatic hyperplasia on a mechanism its own label says has not been established: in a 511-man randomised trial it improved the International Prostate Symptom Score by 2.1 points over placebo against tamsulosin's 1.5, raised peak urine flow by 2.4 mL/sec against tamsulosin's 2.2, and improved erectile function by 4.0 points where tamsulosin managed -0.4 — while a pooled responder analysis of 1,499 patients found 71.1% of treated men reaching a clinically meaningful improvement and 56.0% of the placebo group reaching it too.
Recorded evidence blocks (15)
Q1
What did Tadalafil's largest trial (2760 people) and its longest (7.5 years) measure?
2760 people in Tadalafil's largest registered study, 7.5 years in its longest registered window, measuring All Cause Mortality. ClinicalTrials.gov · 2026-09-01
62 phase3, 53 phase4, 51 phase2, 30 phase1, 23 na, 12 na or unstated, 4 early phase1; NCT05173896; 2029-12. Last human test completed 2026, NCT06805513.
Interpretation These counts include studies where Tadalafil 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
phase3
62
phase4
53
phase2
51
phase1
30
na
23
na or unstated
12
2 more recorded rows
early phase1
4
Last recorded human testNCT06805513
2026-04-02
recorded 2026-09-01 · last checked 2026-09-04
Q2
From mouse to human: where has Tadalafil shown lifespan?
Interpretation All Cause Mortality — the recorded outcome words.
Show the evidence
mouse
lifespan
rat
mechanism-only
humanNCT01302444
lifespan; All Cause Mortality; 224
recorded 2026-09-01 · last checked 2026-09-04
Q3
20 of Tadalafil's trials stopped: safety, futility/efficacy, accrual/recruitment, funding/business, other?
safety (1), futility/efficacy (1), accrual/recruitment (6), funding/business (2) and other (10): Tadalafil's stop wording, clustered. ClinicalTrials.gov · 2026-09-01
"slow recruitment"; 20 of 224 registered studies
Show the evidence
Trial
NCT00215631
terminated; "slow recruitment"
NCT00506701
withdrawn; "due to lack of finance"
NCT00538564
withdrawn; "Trial closed just prior to study receiving Investigational Review Board approval"
NCT01238224
terminated; "Durability of study medications could not be guaranteed after the expire date."
NCT01244620
terminated; "Safety Issue: The trial was prematurely terminated on Dec 9, 2010, due to safety concerns, specifically new emerging evidence of hepatic injury."
NCT01272388
terminated; "We designed a different pilot trial based on data obtained after this study started - the 2 studies were too overlapping to continue both."
14 further recorded trials
NCT01275339
terminated; "Difficulty enrolling patients and PI moved institutions."
NCT01302444
terminated; "One subject enrolled and completed this study. The study was stopped due to poor recruitment."
NCT01326117
withdrawn; "lack of patients who meet inclusion criteria; there was one screen failure"
NCT01374217
terminated; "early stopping rule"
NCT01865084
terminated; "The study is being terminated for lack of efficacy"
NCT01910389
terminated; "terminated by funding agency"
NCT01960153
withdrawn; "Award was ended by NIH for parent study"
NCT02653833
terminated; "PI passed away"
NCT03166787
terminated; "Due to the Pandemic and the nature of this study we decided to terminate this study."
NCT03309592
withdrawn; "Lack of eligible participants and failure to meeting study enrollment."
NCT03785210
terminated; "Study was terminated due to poor accrual."
NCT04052269
suspended; "suspended due to COVID"
NCT04069936
terminated; "Resourcing"
NCT05458232
withdrawn; "No subjects enrolled"
recorded 2026-09-01 · last checked 2026-09-04
Q4
Human studies of Tadalafil used Tadalafil 2.5 mg — over how long?
0; NCT00506701; NA; the smallest recorded human enrolment at or below 30; the registry states no direction of its result; WITHDRAWN
Q7
Which of 6 min walking test, 6 minute walk distance and 6 minute walk test did Tadalafil's trials measure?
6 min walking test, 6 minute walk distance and 6 minute walk test lead 40 outcome terms across Tadalafil's trials. ClinicalTrials.gov · 2026-09-01
recurrent priapism frequency, choice of treatment for use in the extension phase, choice of drug at visit 5, adverse events, beta cell function and insulin sensitivity follow.
Show the evidence
visual persistence
1
reaction time
1
6 min walking test
1
recurrent priapism frequency
1
choice of treatment for use in the extension phase
1
choice of drug at visit 5
1
14 more recorded rows
adverse events
1
beta cell function
1
insulin sensitivity
1
total international prostate symptom at week 12 endpoint
1
pulmonary vascular resistance
1
time to discontinuation of randomized treatment
1
6 minute walking distance
1
time to reach maximum observed plasma concentration
1
trough plasma concentrations
1
maximum observed plasma concentration
1
area under the curve of the 24 hour dosing interval
1
apparent oral clearance
1
volume of distribution at steady state
1
all cause mortality
1
recorded 2026-09-01 · last checked 2026-09-04
Q8
Which of Tadalafil's 26 ongoing trials reports first?
Oral glucose tolerance test; Feasibility of treatment defined as proportion of participants achieving full target dose of tadalafil/placebo.; latest 2029-12
Show the evidence
Trial
NCT05051436
"The Effects of Mirabegron and Tadalafil on Glucose Tolerance in Prediabetics"; n 96; "Oral glucose tolerance test"; 2027-01
NCT05173896
"Improving Cerebral Blood Flow and Cognition in Patients with Cerebral Small Vessel Disease. the ETLAS-2 Trial"; n 100; "Feasibility of treatment defined as proportion of participants achieving full target dose of tadalafil/placebo."; 2029-12
NCT05195775
"Tadalafil as Adjuvant Therapy for DMD"; n 25; "Change in post-contractile BOLD response after tadalafil dosing"; 2025-09-05
NCT05206955
"Study of Tadalafil vs. Placebo for Improving Hemodynamics and End-Organ Dysfunction in Fontan Physiology"; n 42; "Microvascular endothelial function"; 2026-11
NCT05558007
"Safety and Efficacy Evaluation of BZ371A Topically Applied on Prostatectomized Patients"; n 72; "Change in Assisted Erectile Function"; 2025-01-31
NCT05709574
"Tadalafil Effect + Chemotherapy in Resectable Gastric/GEJ Cancer"; n 11; "Evaluating the safety and tolerability of tadalafil treatment with FLOT chemotherapy by assessing the number of participants with treatment related adverse events usting CTCAE v. 5.0."; 2026-10-30
14 further recorded trials
NCT05844462
"Tadalafil for Severe Pulmonary Hypertension Due to Chronic Obstructive Pulmonary Disease"; n 200; "6 minute Walk"; 2027-12
NCT05937854
"Breathe Easier With Tadalafil Therapy for Dyspnea in COPD-PH"; n 126; "severity of patient-reported dyspnea"; 2029-03-01
NCT06290713
"Vasodilator and Exercise Study for DMD (VASO-REx)"; n 50; "Vascular responsiveness after muscle contraction to a single dose of tadalafil."; 2026-11
NCT06442020
"Low Intensity Shock Wave Therapy in the Rehabilitation Treatment of Erectile Dysfunction After Robotic Radical Prostatectomy."; n 158; "Impact of LiESWT"; 2026-09-15
NCT06583590
"Evaluation of Efficacy of Botulinum Toxin A Plus Oral Tadalafil 5 mg in Diabetic Men With Erectile Dysfunction"; n 32; "Treatment."; 2025-12-01
NCT06968962
"Comparison of Sequential to Initial Combination Therapy in PAH"; n 376; "The change of 6MWD at month 12 from baseline"; 2028-12
NCT07172815
"PDE5 Inhibitor for Alzheimer's Disease"; n 244; "To assess the safety and tolerability of long-term (1 year) tadalafil treatment in MCI and early AD patients."; 2028-08
NCT07177326
"Combination Therapy of Tadalafil 2.5mg Plus Sildenafil 25mg Versus Tadalafil 5 mg Monotherapy for Treatment of Erectile Dysfunction: A Randomized, Placebo-Controlled Double-Blinded Cross-Over Study"; n 142; "Change in Erectile Function (IIEF-5 Score)"; 2026-12-01
NCT07245680
"COMMODITIES Trial: Initial Dual Oral Therapy vs Monotherapy in PAH With Cardiovascular Comorbidities"; n 186; "Mesurement of the risk profile according to the non-invasive 4-risk strata method"; 2029-02-14
NCT07416968
"Randomized Controlled Trial Comparing Low Dose Tadalafil Versus Solifenacin For Management of Overactive Bladder in Women: Multicenter Egyptian National Study"; n 480; "Overactive Bladder Symptom Score percentage reduction"; 2026-12
NCT07466030
"Tadalafil 5 mg on Storage Lower Urinary Tract Symptoms After Anatomical Endoscopic Enucleation of the Prostate"; n 40; "Proportion of patients achieving stress urine incontinence at 12 weeks post op, assessed by IPSS score"; 2028-09-01
NCT07499804
"Effect of Tadalafil on Endometrial Thickness and Frozen Embryo Transfer Outcomes"; n 100; "pregnancy"; 2026-04-30
NCT07537855
"Efficacy of Intracavernosal Xeomin With Tadalafil for Mild-Moderate Erectile Dysfunction"; n 30; "Change in erectile function"; 2028-09
NCT07562282
"Safety and Efficacy of Combination of Tamsulosin 0.4 mg Plus Tadalafil 5mg Versus 2.5 mg"; n 140; "Evaluation of Ureteral Stent Symptoms"; 2026-07-10
recorded 2026-09-01 · last checked 2026-09-04
Q9
Which running trial of Tadalafil could settle insulin sensitivity?
NCT05051436 measures Oral glucose tolerance test, reading out 2027-01.
2 open trials; n 96; "The Effects of Mirabegron and Tadalafil on Glucose Tolerance in Prediabetics"
Show the evidence
Trial
NCT05051436
"The Effects of Mirabegron and Tadalafil on Glucose Tolerance in Prediabetics"; n 96; "Oral glucose tolerance test"; 2027-01
NCT05844462
"Tadalafil for Severe Pulmonary Hypertension Due to Chronic Obstructive Pulmonary Disease"; n 200; "6 minute Walk"; 2027-12
Q10
Which 83 trials of Tadalafil posted no result?
Posted no result
83 of 83 completed trials
Registrations
NCT00707187, NCT00050609, NCT00547508, NCT00644956, NCT00547573 and NCT00547599, and 77 more
Completion dates
oldest 2002-07; newest 2024-08-30
Show the evidence
Trial
NCT00707187
2002-07
NCT00050609
2003-09
NCT00547508
2003-09
NCT00644956
2003-11
NCT00547573
2003-12
NCT00547599
2004-01
14 further recorded trials
NCT00547417
2004-03
NCT00547287
2004-05
NCT00668109
2004-06
NCT00663130
2004-07
NCT00547092
2004-11
NCT00547495
2004-11
NCT00122499
2005-02
NCT00547183
2005-05
NCT00174486
2005-06
NCT00421083
2005-06
NCT00547352
2005-06
NCT00547625
2005-07
NCT00422578
2005-09
NCT00382135
2005-12
Q11
At the median, Tadalafil's trials enrolled 80 people — anything larger?
Median enrolment
80
Largest enrolment
2760
Registered trials counted
223
Q12
What do 4850 spontaneous reports say about Tadalafil — 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.
Tadalafil appears in spontaneous reports to regulators. Across the 10 most-reported reaction terms, 4850 reaction mentions were counted: headache 1223; dyspnoea 1073; hypotension 494; back pain 405. open-targets-adr · CHEMBL779 · 2026-06-24
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headache
1223
dyspnoea
1073
hypotension
494
back pain
405
flushing
309
fluid retention
288
4 more recorded rows
hospitalisation
274
vision blurred
269
syncope
260
pulmonary arterial hypertension
255
recorded 2026-06-24 · last checked 2026-09-04
Q13
Tadalafil and CYP2C19, CYP2C9 and CYP2D6: shared by which compounds?
CYP2C19, CYP2C9 and CYP2D6 appear in Tadalafil's recorded interaction sentences, 5 in all. openfda-label+europepmc · 2026-08-30
Interpretation pharmacokinetics
Show the evidence
CYP2C19
pharmacokinetics
Bosentan, a substrate of CYP2C9 and CYP3A and a moderate inducer of CYP3A, CYP2C9 and possibly CYP2C19, reduced tadalafil systemic exposure following multiple-dose co-administration (Figure 2).
pharmacokinetics
Exposure changes of tadalafil following co-administration with other drugs are shown in Figure 2. a Ritonavir is also a CYP2C9/CYP2C19/CYP2D6 Inhibitor and CYP3A inducer. b [see Dosage and Administration (2.4)]. c Bosentan is also a CYP2C9/CYP2C19 inducer.
CYP2C9
pharmacokinetics
Bosentan, a substrate of CYP2C9 and CYP3A and a moderate inducer of CYP3A, CYP2C9 and possibly CYP2C19, reduced tadalafil systemic exposure following multiple-dose co-administration (Figure 2).
pharmacokinetics
Exposure changes of tadalafil following co-administration with other drugs are shown in Figure 2. a Ritonavir is also a CYP2C9/CYP2C19/CYP2D6 Inhibitor and CYP3A inducer. b [see Dosage and Administration (2.4)]. c Bosentan is also a CYP2C9/CYP2C19 inducer.
CYP2D6pharmacokinetics
Exposure changes of tadalafil following co-administration with other drugs are shown in Figure 2. a Ritonavir is also a CYP2C9/CYP2C19/CYP2D6 Inhibitor and CYP3A inducer. b [see Dosage and Administration (2.4)]. c Bosentan is also a CYP2C9/CYP2C19 inducer.
recorded 2026-08-30 · last checked 2026-09-04
Q14
Was Tadalafil studied with exercise?
exercise is named in Tadalafil's label sentences: "Before administration of tadalafil and after the trial, ventricular function (MPI, EF, FS, E/A, VTI), exercise performance, and endothelial function were evaluated for sonographic and biochemical markers (FMD, IMT, ICAM, VCAM, NO) using echocardiography, exercise testing, vascular ultrasonography,…" openfda-label+europepmc · 2026-08-30
1 recorded statement; exercise
Show the evidence
exercise
Before administration of tadalafil and after the trial, ventricular function (MPI, EF, FS, E/A, VTI), exercise performance, and endothelial function were evaluated for sonographic and biochemical markers (FMD, IMT, ICAM, VCAM, NO) using echocardiography, exercise testing, vascular ultrasonography, and biochemical measurements, respectively.
recorded 2026-08-30 · last checked 2026-09-04
Q15
What is recorded about Tadalafil and autophagy?
"This study explores the effects of phosphodiesterase inhibitors (PDEIs) roflumilast (RF), rolipram (ROL), and tadalafil (TAD) on SESN2 expression and autophagy in Aβ25-35-treated hippocampal neuron (HT-22) cell cultures." — where Tadalafil and autophagy appear together. Europe PMC · pathway abstract search · 2025-10-23
"This study explores the effects of phosphodiesterase inhibitors (PDEIs) roflumilast (RF), rolipram (ROL), and tadalafil (TAD) on SESN2 expression and autophagy in Aβ25-35-treated hippocampal neuron (HT-22) cell cultures."
NAD+PMID 41131545
"Transcriptomic analysis revealed that tadalafil modulates MDSC metabolism, upregulates NAD<sup>+</sup> nucleotidase activity, and disrupts chemotaxis-related transcriptional programs, including downregulation of key chemokine receptors."
AMPKPMID 36754339
"Our study revealed that tadalafil restored SIRT1 expression and activity and activated AMPK by increasing its phosphorylation."
sirtuinPMID 36754339
"Our study revealed that tadalafil restored SIRT1 expression and activity and activated AMPK by increasing its phosphorylation."
AMPKPMID 39941283
"Additionally, there is ongoing debate regarding the efficacy of other treatments, such as free radical scavengers, alpha-lipoic acid (ALA), dimethyl fumarate (DMF), adenosine monophosphate-activated protein kinase (AMPK) activators such as metformin, and phosphodiesterase-5 inhibitors such as tadalafil. <b>Conclusions</b>: The controversies surrounding the mechanisms, diagnosis, and treatment of…"
sirtuinPMID 35229761
"The expression of SIRT1 was modulated in aged Sprague-Dawley rats following intragastric administration of resveratrol (Res; 5 mg kg<sup>-1</sup>), niacinamide (NAM; 500 mg kg<sup>-1</sup>) or Res (5 mg kg<sup>-1</sup>) + tadalafil (Tad; phosphodiesterase-5 [PDE5] inhibitor; 5 mg kg<sup>-1</sup>) for 8 weeks."
7 more recorded rows
mTORPMID 36036333
"We previously observed that diabetic mice treated with tadalafil and HCQ had significantly reduced fasting blood glucose and lipid levels, increased plasma insulin and insulin-like growth factor-1 levels, and improved insulin sensitivity, along with smaller myocardial infarct size following I/R. The combination treatment activated Akt/mTOR cellular survival pathway, which was likely responsible…"
IGF-1PMID 36036333
"We previously observed that diabetic mice treated with tadalafil and HCQ had significantly reduced fasting blood glucose and lipid levels, increased plasma insulin and insulin-like growth factor-1 levels, and improved insulin sensitivity, along with smaller myocardial infarct size following I/R. The combination treatment activated Akt/mTOR cellular survival pathway, which was likely responsible…"
sirtuinPMID 24727492
"Since phosphodiesterase-5 inhibitors potentiate NO signaling, we hypothesized that chronic treatment with phosphodiesterase-5 inhibitor tadalafil would activate SIRT1-PGC-1α signaling and protect against metabolic stress-induced mitochondrial dysfunction in diabetic hearts."
mTORPMID 25752605
"Tadalafil inhibited high glucose-induced activation of mechanistic target of rapamycin complex 1 and laminin γ1 accumulation in an AMP-activated protein kinase (AMPK)-dependent manner."
AMPKPMID 25752605
"Tadalafil inhibited high glucose-induced activation of mechanistic target of rapamycin complex 1 and laminin γ1 accumulation in an AMP-activated protein kinase (AMPK)-dependent manner."
mTORPMID 25752605
"We conclude that tadalafil amelioration of high glucose stimulation of synthesis of proteins including matrix proteins in podocytes requires integration of the NO-H2S-AMPK axis leading to the inhibition of high glucose-induced mechanistic target of rapamycin complex 1 activity and mRNA translation."
autophagyPMID 23512808
"The effect of tadalafil, a phosphodiesterase 5 inhibitor (PDE5I), on burn-induced skeletal muscle autophagy is documented and extends our published results that PDE5Is attenuates muscle degeneration in a muscular dystrophy model."
recorded 2025-10-23 · last checked 2026-09-04
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