This page shows what was measured, who it was measured in, and what that does not settle.
What Anastrozole does in the body
Anastrozole sits in its active site and stops it working.
Aromatase is the enzyme that turns testosterone into oestrogen. Two things follow. Oestradiol falls, and because the brain was using oestradiol as its main signal that there is enough sex hormone around, it stops holding back: LH rises and the testes make more testosterone. So the drug raises testosterone by removing a brake rather than by supplying hormone. The catch is that male bone needs oestradiol more than it needs testosterone, so the same block that raises the number a man is watching also lowers the density of his spine.
Why people take it. Breast cancer, or unapproved use in men to lower oestrogen and raise testosterone.
What happened in people
It raised testosterone in older men, but did not improve quality of life or erections and reduced spine bone density.
✓ Reviewed first-read answer
Where this came from
A person wrote this and a reviewer approved it against this exact record. It carries no effect size.
A reviewer approved this against this record. The reviewed-claim record carrying the exact population and effect size does not exist yet.
No source is stored against this line.
The limit that matters most
Hormone and sperm improvements from baseline did not outperform the medicines usually used for comparison.
Where it acts
Aromatase in adipose tissue, muscle, liver, bone and Leydig cells; downstream at the hypothalamus and pituitary
Kind of result
Symptoms and quality of life
Supervision
Professional supervision is normally required. A regulator classifies this substance in a way that restricts how it is supplied.
What the registries record it as
The substance registry classes this as chemical.
FDA substance registry · 2Z07MYW1AZ · read 2026-08-29
Its recorded molecular formula is C17H19N5, weighing 293.4.
US prescribing information · aabd8f88-2b52-4d43-8dc6-61605988c4dc · 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.
A reviewer approved this sentence against this exact record and its sources.
The limit a reviewer approved as the one that matters most here.
The four opening statements run to 133 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
Muscle
∅Nothing in the sources checkedNo registered study lists a life outcome for this goal.
∅Nothing in the sources checkedNo registered study lists a performance measure for this goal.
∅Nothing in the sources checkedNo registered study lists a symptom measure for this goal.
△Only a number moved1 registered test measure.
∅Nothing in the sources checkedNo registered study lists a body-step measure for this goal.
—Not recordedHarms were not a registered measure for this goal.
—Not recordedNo finished study window is recorded.
…Waiting for a reviewerWho was studied is listed further down the page.
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 moved1 registered test measure.
∅Nothing in the sources checkedNo registered study lists a body-step measure for this goal.
—Not recordedHarms were not a registered measure for this goal.
—Not recordedNo finished study window is recorded.
…Waiting for a reviewerWho was studied is listed further down the page.
Body weight
∅Nothing in the sources checkedNo registered study lists a life outcome for this goal.
∅Nothing in the sources checkedNo registered study lists a performance measure for this goal.
∅Nothing in the sources checkedNo registered study lists a symptom measure for this goal.
△Only a number moved1 registered test measure.
∅Nothing in the sources checkedNo registered study lists a body-step measure for this goal.
—Not recordedHarms were not a registered measure for this goal.
—Not recordedNo finished study window is recorded.
…Waiting for a reviewerWho was studied is listed further down the page.
Endurance
∅Nothing in the sources checkedNo registered study lists a life outcome for this goal.
…Waiting for a reviewer1 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.
Which registered measures put each goal on this table
Muscle
lean body mass
Blood sugar
insulin sensitivity
Body weight
muscle and body fat distribution
Endurance
vo2 max
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
1 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.
Bioavailable and total testosterone, oestradiol and LH, with quality of life, erectile function, prostate symptom score and PSA as secondary measures
✓ The study showed what it set out to show
Who was studied
Leder 2004 randomised trial in elderly men with low testosterone
Total testosterone 343 to 572 ng/dL on 1 mg daily, P < 0.001 versus placebo; oestradiol 26 to 17 pg/mL, P < 0.001; LH 5.1 to 7.9 U/L, P = 0.007
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. MOS SF-36, International Index of Erectile Function, AUA Symptom Index and haematocrit were unchanged. PSA rose in the twice-weekly group only, 1.7 to 2.2 ng/mL, P = 0.031 versus placebo.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet, 1 mg once daily
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
Testosterone 319 to 524 ng/dL at month 3, P < 0.0001; oestradiol 15 to 12 pg/mL, P < 0.0001; posterior-anterior spine BMD decreased versus placebo, P = 0.0014
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. Bone turnover markers were not affected, so the density loss was not accompanied by a measurable turnover signal at one year.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet, 1 mg once daily
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
Dias 2016 three-arm trial: testosterone gel versus anastrozole versus placebo
How many people
43
Study design
Randomised double-blind placebo-controlled proof of concept, 12 months
Compared against
A dummy treatment
Kind of result
A number that stands in for health
What was found
Testosterone gel improved lumbar spine BMD at 12 months (P < 0.01); anastrozole did not, despite both arms raising total testosterone above 500 ng/dL. Lean body mass rose only on anastrozole, 1.49 +/- 0.38 kg at 6 months (P < 0.01)
Repeated elsewhere
Unreplicated
What this does not prove. A study that did not show an effect does not show that no effect exists anywhere.
The limits of this study, and where it came from
Main limit. No limitation is recorded for this study.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet, 1 mg once daily
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
Anastrozole 38.5% versus placebo 31.4%; odds ratio 1.513 (95% CI 0.496-4.844), P = 0.47. Median change in testosterone-to-oestradiol ratio 166% versus 39%
Repeated elsewhere
Unreplicated
What this does not prove. A study that did not show an effect does not show that no effect exists anywhere.
The limits of this study, and where it came from
Main limit. No limitation is recorded for this study.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet, 1 mg once daily
Interval reported. 95% CI 0
Written into the record, not signed off as a reviewed claim.
RNAWiki holds 4 written-up human studies for this substance, each with the question it asked.
How we know it
Each card names the study, the number of people and what the study set out to measure.
What this does not prove
These summaries were written by a person and have not been signed off as reviewed claims.
Why it matters
A study that failed is as informative as one that worked, and both are here.
What we still do not know
No reviewed claim exists, so no exact population, effect size or interval is published yet.
What happened in people◇Read from sources, not yet reviewed
How close this is to real life
The top step is something a person would feel or care about. The bottom is a guess from software. Filled steps are where evidence exists for this substance.
■Living longer, or avoiding a major eventEvidence recorded. Death, a heart attack, a stroke, a hospital stay.9 registered measures of this kind. No reviewed result.
■What a body can do day to dayEvidence recorded. Walking, dressing, breathing, recovering.1 registered measure of this kind.
■Measured performanceEvidence recorded. How much was lifted, how far was run, how fast.1 registered measure of this kind.
□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.5 registered measures of this kind.
■A step measured inside a personEvidence recorded. Something measured in human tissue or human cells.2 registered measures inside human tissue.
■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.
Start
Anastrozole
What a person takes: Oral tablet, 1 mg once daily.
The measurement behind this step
A small immediate-release tablet, well absorbed, dosed once daily. Off-label male regimens run from 1 mg daily down to 0.5 mg twice weekly, and unlicensed liquid preparations dosed by dropper are sold alongside SARMs, where inaccurate dosing pushes oestradiol below the male range rather than into it.
Getting in
A once-daily oral tablet with near-complete absorption
One 1 mg tablet a day is enough to suppress most oestrogen production for a full day.
──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
Anastrozole is well absorbed orally with a terminal half-life supporting once-daily dosing. At the approved 1 mg dose it suppresses whole-body oestrogen production by more than 90% in the approved population. Because inhibition is competitive and reversible, the block tracks plasma concentration rather than persisting after clearance.
Reaches aromatase inside adipose, muscle and gonadal cells
The enzyme sits inside cells, mostly in fat tissue, so the drug has to enter those cells to reach it.
──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
Passive distribution into aromatase-expressing tissue — adipose, skeletal muscle, liver, bone and Leydig cells. In men, peripheral adipose conversion is the dominant source of circulating oestradiol, which is why obesity raises oestradiol and lowers testosterone and why the off-label male indication clusters in obese men.
A nitrogen atom in the drug grips the iron at the heart of the enzyme, which is exactly where the reaction needs to happen.
╌╌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 triazole nitrogen coordinates the haem iron of CYP19A1, competitively blocking the three-step oxidative aromatisation of the steroid A ring. Androstenedione is no longer converted to oestrone and testosterone is no longer converted to oestradiol; substrate accumulates upstream.
Oestradiol falls, the pituitary brake comes off, LH rises
With less oestrogen reaching the brain, the pituitary pushes harder on the testes.
──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
Oestradiol is the principal negative-feedback signal on GnRH and LH in men. Removing it raises LH — measured at 5.1 to 7.9 U/L on 1 mg daily — which drives Leydig cell testosterone synthesis. Total testosterone rises by roughly 50-70% from baseline in the elderly-male trials while oestradiol stays within, but at the bottom of, the male reference range.
Testosterone measurements go up. Bone density at the spine goes down, and the symptom scores stay where they were.
──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
Across the male randomised trials: lumbar spine BMD fell against placebo over one year at 1 mg daily, and in a three-arm comparison only the testosterone gel arm improved spine BMD. Quality of life, erectile function and urinary symptom scores were unchanged at 12 weeks. Lean body mass rose by about 1.2-1.5 kg on anastrozole in the one-year trial. Oestradiol in men is the dominant sex steroid for bone, and this mechanism removes it by design.
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.
No registered study measured anything of this kind.
Measured
Things only a test, a scale or a device shows.
lumbar spine bone mineral density
lean body mass
blood concentrations
insulin sensitivity
muscle and body fat distribution
vo2 max
muscle biopsy analysis
ki 67 levels from baseline to day 28 biopsy samples
Meaningful
Things that change how a life goes, not only a number.
progression free survival
evaluation of the disease free survival
progression free survival at 1 year
event free survival
overall survival
disease free survival
time to disease progression
5 year disease free survival
disease free survival events
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 (23)
adverse events
overall clinical response rate
complementary deoxyribonucleic acid expression
free from breast cancer
clinical benefit rate
time to tumor progression
time to progression
local tumor control
growth rate
overall response rate in both arms
time to progression expert evaluation committee assessment
objective response rate
ovulation rate in cycle 1
overall objective tumor response rate
toxicity
objective tumour response
clinical response rate
resting metabolic rate
identification of predictive markers
recurrence free rate
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. 50 hours hours
Read from the label, which states: “Hepatic metabolism accounts for approximately 85% of anastrozole elimination. Renal elimination accounts for approximately 10% of total clearance. The mean elimination half-life of anastrozole is 50 hours.”
How long effects linger.RNAWiki does not store this separately, and never works it out from another figure on this page.
Beyond the studies. Nothing is recorded about the long term.
The longest finished study sets the edge of what anyone measured.
A study window is not how long people took it, and neither is how long they were followed. Where RNAWiki holds only one of the three, it shows one.
What is missing or unclear◇Read from sources, not yet reviewed
Were people like you studied?
RNAWiki cannot tell whether a study fits you. It can show who was in it, and where the result stops carrying.
Who was studied
People similar to this profile were included.
On label, postmenopausal women with breast cancer. Off label, men who want higher testosterone without an injection, men trying to control oestrogen-related effects during anabolic steroid use, men with obesity-associated low testosterone, and subfertile men with a low testosterone-to-oestradiol ratio.
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: “Clinical studies in pediatric patients included a placebo-controlled trial in pubertal boys of adolescent age with gynecomastia and a single-arm trial in girls with McCune-Albright Syndrome and progressive precocious puberty.”
US prescribing information · aabd8f88-2b52-4d43-8dc6-61605988c4dc · read 2026-08-30
On older people, the label states: “In studies 0030 and 0027, about 50% of patients were 65 or older.”
US prescribing information · aabd8f88-2b52-4d43-8dc6-61605988c4dc · read 2026-08-30
On people who are pregnant, the label states: “Risk Summary Based on findings from animal studies and its mechanism of action, anastrozole may cause fetal harm when administered to a pregnant woman [see Clinical Pharmacology (12.1) ] .”
US prescribing information · aabd8f88-2b52-4d43-8dc6-61605988c4dc · read 2026-08-30
On people who are breastfeeding, the label states: “Risk Summary There are no data on the presence of anastrozole or its metabolites in human milk, or its effects on the breast-fed child or on milk production.”
US prescribing information · aabd8f88-2b52-4d43-8dc6-61605988c4dc · read 2026-08-30
On people with reduced liver function, the label states: “The plasma anastrozole concentrations in the subjects with hepatic cirrhosis were within the range of concentrations seen in normal subjects across all clinical trials.”
US prescribing information · aabd8f88-2b52-4d43-8dc6-61605988c4dc · read 2026-08-30
On people with reduced kidney function, the label states: “Since only about 10% of anastrozole is excreted unchanged in the urine, the renal impairment does not influence the total body clearance.”
US prescribing information · aabd8f88-2b52-4d43-8dc6-61605988c4dc · read 2026-08-30
Where the result stopped carrying
The pubertal gynaecomastia trial, run by the manufacturer, missed its primary endpoint outright
The one-year bone trial reversed the expected direction: aromatase inhibition lowered spinal bone density instead of raising it
The symptom, sexual function and urinary endpoints in the elderly-male trial were flat despite a large hormonal response
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, 1 mg once daily
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The form and route recorded on this substance.
No source is stored against this line.
Who oversees it
Professional supervision is normally required. A regulator classifies this substance in a way that restricts how it is supplied.
❝ Quoted from a source
Where this came from
Copied from a source RNAWiki stored, with the source named.
Suppression classes recorded: S3.
No source is stored against this line.
What is in the pack
A small immediate-release tablet, well absorbed, dosed once daily. 5 mg twice weekly, and unlicensed liquid preparations dosed by dropper are sold alongside SARMs, where inaccurate dosing pushes oestradiol below the male range rather than into it.
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
Recorded notes on how this is sold and what that means for what is in the pack.
No source is stored against this line.
Where it is registered
Regulatory records are listed in the technical disclosure at the foot of this page.
# Counted from records
Where this came from
A count of rows RNAWiki holds. It describes our records, not your body.
Register entries are stored per jurisdiction and shown with their dates.
No source is stored against this line.
Why people stop
Not recorded.
∅ Nothing recorded
Where this came from
RNAWiki holds nothing here and says so rather than guessing.
No record of why people stopped taking it is stored for this substance.
No source is stored against this line.
What it would be like to take◇Read from sources, not yet reviewed
What can go wrong
Sorted by where each line came from. A regulator's label and a report somebody sent in are not the same kind of fact.
·Worth asking a clinician aboutWritten into the record from the studies named on this page
Labelled risks in the approved population: decreased bone mineral density at lumbar spine and total hip, increased total cholesterol, and in women with pre-existing ischaemic heart disease an increased rate of ischaemic cardiovascular events. In men the measured findings are a fall in lumbar spine bone mineral density over one year against placebo, no change in quality of life, erectile function or urinary symptoms at 12 weeks, and a PSA rise in one dosing arm. Long-term male safety data do not exist because no male trial ran beyond one year.
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.
Anastrozole appears in spontaneous reports to regulators. Across the 10 most-reported reaction terms, 10605 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, 1 mg once daily
✎ 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
5 mg twice weekly, and unlicensed liquid preparations dosed by dropper are sold alongside SARMs, where inaccurate dosing pushes oestradiol below the male range rather than into it.
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
Recorded notes on which forms are sold and how they compare.
No source is stored against this line.
What is recorded as being sold
63 products list this as an active ingredient in the United States drug directory. 63 of them contain it and nothing else.
FDA National Drug Code directory · 76420-004 · read 2026-08-29
They are sold as powder, powder, for suspension, tablet, tablet, coated and tablet, film coated, taken oral.
FDA National Drug Code directory · 76420-004 · read 2026-08-29
The regulator's established pharmacologic class for it is aromatase inhibitor [epc] and aromatase inhibitors [moa].
FDA National Drug Code directory · 76420-004 · read 2026-08-29
40 published labels name it as an active ingredient. 40 of them describe this substance alone, which is where its own label text on this page comes from.
US prescribing information · aabd8f88-2b52-4d43-8dc6-61605988c4dc · read 2026-08-29
Those labels are classed as human prescription drug.
US prescribing information · aabd8f88-2b52-4d43-8dc6-61605988c4dc · read 2026-08-29
Anastrozole is film-coated tablets at 1 mg tablets, recorded as prescription product; fda label in effect 2026-02-11 in the United States.
US prescribing information · 03586c40-eb32-45c5-beb7-6762a6b78790 · read 2026-08-28
Recorded price in US: 0.14007 USD per one unit as the pricing file counts it — a tablet, capsule, patch or single item, across 21 priced products whose strengths and pack forms differ, as of 2026-08-26, paid by retail pharmacies buying the product, as surveyed by the Centers for Medicare & Medicaid Services. It is not a list price, an insurance price, or what anyone pays at a counter..
Recorded source · 2026-08-26 · read 2026-08-28
Evidence carries across two names for one substance. It does not carry across a salt, a mirror form or a mixture.
What it would be like to take◇Read from sources, not yet reviewed
What you could measure
This one is decided with a clinician, so this section holds questions to ask rather than a plan to run.
Self-experiment planning is not offered for a prescription or clinician-supervised medicine. The questions below are for a clinician or pharmacist.
Questions worth asking
Which of the trials of Anastrozole 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 a higher testosterone level obtained by blocking aromatase carries the benefits of a higher testosterone level obtained any other way — the bone data specifically contradict this
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 controlling the testosterone-to-oestradiol ratio controls gynaecomastia, which the manufacturer own randomised trial failed to show
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 aromatase inhibitors improve male fertility outcomes, when pooled trials show no advantage over SERMs or hCG and slightly worse motility
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 "oestrogen control" during anabolic steroid use is a studied practice; no randomised trial of an aromatase inhibitor alongside exogenous androgens exists
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 Anastrozole 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 raises testosterone into the youthful normal range
In plain words
In elderly men with low testosterone, 1 mg daily raised total testosterone from an average of 343 to 572 ng/dL over 12 weeks, and LH rose too.
What was measured
Total and bioavailable testosterone, oestradiol and LH at 12 weeks against placebo in men aged 62-74
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Leder et al. randomised 37 men aged 62-74 with screening testosterone below 350 ng/dL to anastrozole 1 mg daily (n=12), anastrozole 1 mg twice weekly (n=11) or placebo (n=14) for 12 weeks. Bioavailable testosterone rose from 99 +/- 31 to 207 +/- 65 ng/dL on daily dosing and from 115 +/- 37 to 178 +/- 55 ng/dL on twice-weekly dosing (both P < 0.001 versus placebo). Total testosterone rose from 343 +/- 61 to 572 +/- 139 ng/dL and from 397 +/- 106 to 520 +/- 91 ng/dL respectively (both P < 0.001 versus placebo). Oestradiol fell from about 26 to 17 pg/mL in both active groups (P < 0.001 versus placebo) but stayed within the normal male range. LH rose from 5.1 to 7.9 U/L on daily dosing (P = 0.007 versus placebo). The authors closed by stating that the physiological consequences of these changes remained to be determined — a caveat that later trials answered rather than confirmed.
Written into the record, not signed off as a reviewed claim
The hormones moved and the symptoms did not
In plain words
In the same trial, quality of life scores, erectile function scores, urinary symptom scores and haematocrit were unchanged despite testosterone rising by roughly two-thirds.
What was measured
MOS SF-36, International Index of Erectile Function, AUA Symptom Index and haematocrit at 12 weeks
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
Leder et al. measured, alongside the hormone panel, the MOS Short-Form Health Survey, the International Index of Erectile Function, the American Urological Association Symptom Index and haematocrit. None changed. Serum prostate-specific antigen rose in the twice-weekly group only, from 1.7 +/- 1.0 to 2.2 +/- 1.5 ng/mL (P = 0.031 versus placebo). This is the pattern that recurs through the whole male off-label literature: the biochemical endpoint responds strongly and reproducibly, and the endpoints a man would notice do not follow it. A drug that reliably moves a number is not the same as a drug that reliably does something.
Written into the record, not signed off as a reviewed claim
Raising testosterone this way lowers spinal bone density
In plain words
A one-year randomised trial in 69 older men found that anastrozole raised testosterone as expected and reduced bone density at the spine compared with placebo.
What was measured
That raising testosterone by blocking aromatase gives the skeletal benefit of raising testosterone, when oestradiol is the dominant sex steroid for male bone and this route removes it
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Burnett-Bowie et al. ran a one-year double-blind randomised placebo-controlled trial in 69 men aged 60 and over with borderline or low testosterone and hypogonadal symptoms, using anastrozole 1 mg daily. Mean serum testosterone rose from 319 +/- 93 ng/dL at baseline to 524 +/- 139 ng/dL at month 3 (P < 0.0001), settling at 474 +/- 145 ng/dL at one year. Oestradiol fell from 15 +/- 4 to 12 +/- 4 pg/mL (P < 0.0001). Posterior-anterior lumbar spine bone mineral density decreased in the anastrozole group relative to placebo (P = 0.0014): from 1.121 +/- 0.141 to 1.102 +/- 0.138 g/cm2 on drug, while placebo rose from 1.180 +/- 0.145 to 1.189 +/- 0.146 g/cm2. Bone turnover markers were unaffected. The authors concluded that aromatase inhibition does not improve skeletal health in ageing men with low or low-normal testosterone. The Arimidex label carries the same signal in its approved population: a bone mineral density decrease at lumbar spine and total hip in the ATAC substudy.
Written into the record, not signed off as a reviewed claim
Head to head against a testosterone gel, only the gel helped bone
In plain words
Forty-three older men were randomised to testosterone gel, anastrozole or placebo for a year. Both raised testosterone above 500 ng/dL. Only the gel improved spine bone density; only anastrozole increased lean body mass.
What was measured
Lumbar spine bone mineral density, lean body mass, knee strength and fast gait speed at 12 months across three arms
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Dias et al. ran a proof-of-concept randomised, double-blind, placebo-controlled, parallel-group single-centre trial in 43 men aged 65-82 with total testosterone below 350 ng/dL, assigned to 5 g transdermal testosterone gel (n=16), anastrozole 1 mg daily (n=14) or placebo (n=13) for 12 months, with lumbar spine bone mineral density as the primary outcome. Both active arms raised total testosterone above 500 ng/dL (P < 0.05 versus baseline) and held it stable. At 12 months testosterone gel improved lumbar spine BMD (P < 0.01) and anastrozole did not. Both improved knee strength (P < 0.05), but lean body mass increased only in the anastrozole group, by 1.49 +/- 0.38 kg at 6 months and 1.24 +/- 0.39 kg at 12 months. Testosterone gel improved fast gait speed at 3 and 12 months; anastrozole did not. The authors read this as direct evidence that aromatisation of testosterone is required both for maintaining male bone density and for the gait speed effect.
Written into the record, not signed off as a reviewed claim
It failed its own manufacturer trial in pubertal gynaecomastia
In plain words
AstraZeneca ran a randomised trial of anastrozole in 80 boys with pubertal breast enlargement. The response rate was 38.5% on drug and 31.4% on placebo, a difference that was not significant.
What was measured
Proportion of boys with 50% or greater reduction in ultrasonographic breast volume at 6 months
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
Plourde et al., writing from AstraZeneca, randomised 80 boys aged 11-18 with pubertal gynaecomastia that had not reduced over a preceding 3-month interval to anastrozole 1 mg or placebo once daily for 6 months. Response was defined as a 50% or greater reduction in calculated combined breast volume by ultrasonography. Response occurred in 38.5% on anastrozole and 31.4% on placebo, odds ratio 1.513 (95% CI 0.496-4.844), P = 0.47. The hormonal endpoint moved decisively: median percent change in the testosterone-to-oestradiol ratio was 166% on drug against 39% on placebo. Treatment was well tolerated. This is the cleanest available demonstration that in this drug, a large change in the testosterone-to-oestradiol ratio does not guarantee a change in the tissue it was supposed to act on.
Written into the record, not signed off as a reviewed claim
In male infertility it beats baseline and not the comparators
In plain words
Pooled trials show aromatase inhibitors improve sperm counts and hormones compared with where the man started. Against the drugs they are usually compared with, the advantage disappears.
What was measured
That aromatase inhibitors improve male fertility outcomes, when the pooled data show change from baseline but no advantage over SERMs or hCG and a small disadvantage on motility
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Guo et al. pooled 10 studies of letrozole or anastrozole in 666 men with infertility. Against baseline, treatment significantly increased sperm concentration, total sperm count, LH, FSH, testosterone and the testosterone-to-oestradiol ratio, and reduced oestradiol. Against control groups receiving selective oestrogen receptor modulators or hCG, there was no significant effect on sperm concentration, motility or morphology, except that aromatase inhibitors had less effect on motility than the controls, weighted mean difference -2.55 (95% CI -4.11 to -1.00, p = 0.001). The authors call the evidence base controversial and ask for larger randomised trials. A before-and-after improvement in an untreated infertile cohort is a weak design in a condition with substantial spontaneous variation, and it is most of what exists here.
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.
It does exactly what it is taken for — 1 mg daily raised total testosterone from 343 to 572 ng/dL in elderly men — and in the trials that measured what happened next, quality of life and erectile function did not change and lumbar spine bone mineral density fell against placebo.
Recorded evidence blocks (14)
Q2
What did Anastrozole's largest trial (16989 people) and its longest (24 years) measure?
16989 people in Anastrozole's largest registered study, 24 years in its longest registered window, measuring Changes in Senescence and Secondary Biomarkers, Including TMEM, Mena, and 67LR. ClinicalTrials.gov · 2026-09-01
128 phase2, 76 phase3, 36 phase1, 20 na, 19 na or unstated, 13 phase4, 2 early phase1; NCT00310180; 2030-09-30. Last human test completed 2026, NCT05150652.
Interpretation These counts include studies where Anastrozole 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
128
phase3
76
phase1
36
na
20
na or unstated
19
phase4
13
2 more recorded rows
early phase1
2
Last recorded human testNCT05150652
2026-06-10
recorded 2026-09-01 · last checked 2026-09-04
Q3
From mouse to human: where has Anastrozole shown biomarker?
suspended; "Primary investigator is taking a leave of absence"
NCT00438321
terminated; "PI relocated"
NCT00440180
terminated; "Not able meet target enrollment."
NCT00481845
terminated; "Low accrual"
14 further recorded trials
NCT00543127
terminated; "Unjustified decision of company that funded the trial."
NCT00555477
terminated; "The study was stopped after 69 subjects were enrolled because of poor accrual."
NCT00555867
terminated; "High drop-out rate leads to the conclusion: not enough data will be available to perform proper analyses of data collected after follow-up month 24 visit"
NCT00573755
terminated; "lack of participant accrual"
NCT00661531
terminated; "Poor accrual"
NCT00738777
suspended; "in preparation for an amendment"
NCT00932152
terminated; "Poor enrollment/suspended to accrual; will close per AstraZeneca request"
NCT01151215
terminated; "Futility"
NCT01234532
terminated; "low accrual"
NCT01262274
terminated; "Due to an adverse event revelation."
NCT01368263
terminated; "Due to funding source and lack of accrual"
NCT01394211
terminated; "Slow accrual"
NCT01484041
terminated; "Decision by company to cease development of dovitinib"
NCT01776008
terminated; "Study did not pass Stage 1 interim analysis."
recorded 2026-09-01 · last checked 2026-09-04
Q5
Human studies of Anastrozole used Arimidex 1 mg — over how long?
10 recorded entries; human; tablet; also "Arimidex 1 mg", "Anastrozole 1mg", "Anastrozole 1 mg"
Show the evidence
human
NCT00055302
Arimidex 1 mg
NCT00179517
Anastrozole 1mg
NCT00213148
Anastrozole 1 mg
NCT00213148
Anastrozole 5 mg
NCT00213148
Anastrozole 10 mg
NCT01155947
Arimidex® Tablets 1 mg
4 more recorded rows
humanNCT01545336
tablet; Sugar pill manufactured to mimic Anastrozole 1 mg tablet
humanNCT01602380
arimidex 1mg
humanNCT03024580
Anastrozole 1Mg Tablet
humanNCT03490513
anastrozole (1 mg/day)
recorded 2026-09-01 · last checked 2026-09-04
Q6
Anastrozole's half-life is 50 hours — which schedules were studied?
50 hours, the half-life Anastrozole's label states. openfda-label · 1d1d5818-1594-4f54-90a9-ae9a9afcdc67 · 2026-08-28
Show the evidence
half life
50 hours hours; Hepatic metabolism accounts for approximately 85% of anastrozole elimination. Renal elimination accounts for approximately 10% of total clearance. The mean elimination half-life of anastrozole is 50 hours.
tmax
The mean C max of anastrozole decreased by 16% and the median T max was delayed from 2 to 5 hours when anastrozole was administered 30 minutes after food.
metabolism
Metabolism Metabolism of anastrozole occurs by N-dealkylation, hydroxylation and glucuronidation.
recorded 2026-08-28 · last checked 2026-09-04
Q7
Which of 5 year disease free survival, adverse events and blood concentrations did Anastrozole's trials measure?
5 year disease free survival, adverse events and blood concentrations lead 40 outcome terms across Anastrozole's trials. ClinicalTrials.gov · 2026-09-01
progression free survival, free from breast cancer, evaluation of the disease free survival, clinical benefit rate, progression free survival at 1 year and event free survival follow.
Show the evidence
adverse events
1
overall clinical response rate
1
complementary deoxyribonucleic acid expression
1
progression free survival
1
free from breast cancer
1
evaluation of the disease free survival
1
14 more recorded rows
clinical benefit rate
1
progression free survival at 1 year
1
event free survival
1
time to tumor progression
1
time to progression
1
local tumor control
1
lumbar spine bone mineral density
1
growth rate
1
overall response rate in both arms
1
lean body mass
1
time to progression expert evaluation committee assessment
1
objective response rate
1
ovulation rate in cycle 1
1
overall survival
1
recorded 2026-09-01 · last checked 2026-09-04
Q8
Which of Anastrozole's 64 ongoing trials reports first?
"Hormone Therapy With or Without Combination Chemotherapy in Treating Women Who Have Undergone Surgery for Node-Negative Breast Cancer (The TAILORx Trial)"; n 10273; "5-year Disease-free Survival"; 2030-09-30
NCT01272037
"Tamoxifen Citrate, Letrozole, Anastrozole, or Exemestane With or Without Chemotherapy in Treating Patients With Invasive RxPONDER Breast Cancer"; n 5018; "Invasive Disease-Free Survival (IDFS)"; 2027-01-08
NCT01674140
"S1207 Hormone Therapy With or Without Everolimus in Treating Patients With Breast Cancer"; n 1939; "Invasive Disease-Free Survival (IDFS)"; 2030-01
NCT01723774
"PD 0332991 and Anastrozole for Stage 2 or 3 Estrogen Receptor Positive and HER2 Negative Breast Cancer"; n 84; "Number of Participants With Complete Cell Cycle Arrest at Cycle 1 Day 15 (PIK3CA Wild Type Cohort Only)"; 2026-08-24
NCT01824836
"A Study to Evaluate Genetic Predictors of Aromatase Inhibitor Musculoskeletal Symptoms (AIMSS)"; n 1046; "Associations Between Pre-specified Single Nucleotide Polymorphisms (SNPs) and Discontinuation of Treatment With Aromatase Inhibitor (AI) Due to the Development of Musculoskeletal Symptoms (MSS)"; 2026-12
NCT01953588
"Fulvestrant and/or Anastrozole in Treating Postmenopausal Patients With Stage II-III Breast Cancer Undergoing Surgery"; n 1473; "Rate of endocrine resistant disease-(First Phase)"; 2027-04-01
14 further recorded trials
NCT02057133
"A Study of LY2835219 (Abemaciclib) in Combination With Therapies for Breast Cancer That Has Spread"; n 198; "Number of Participants with One or More Drug-Related Adverse Events"; 2026-12
NCT02246621
"A Study of Nonsteroidal Aromatase Inhibitors Plus Abemaciclib (LY2835219) in Postmenopausal Women With Breast Cancer"; n 493; "Progression Free Survival (PFS)"; 2026-12
NCT02476786
"Endocrine Treatment Alone for Elderly Patients With Estrogen Receptor Positive Operable Breast Cancer and Low Recurrence Score"; n 50; "Response rate"; 2032-07-31
NCT02603679
"Neoadjuvant Response-guided Treatment of Luminal B-type Tumors and Luminal A-type Tumors With Node Metastases"; n 181; "Radiological Objective Response Rate after Completion of the First 12-week Period of Primary Medical Treatment"; 2031-12-31
NCT02763566
"A Study of Abemaciclib (LY2835219) in Participants With Breast Cancer"; n 463; "Progression Free Survival (PFS) (Abemaciclib + NSAI & Placebo NSAI)"; 2028-03
NCT02779751
"A Study of Abemaciclib (LY2835219) in Participants With Non-Small Cell Lung Cancer or Breast Cancer"; n 100; "Number of Participants with One or More Serious Adverse Event(s) (SAEs)"; 2026-12
NCT02942355
"Trial of Anastrozole and Palbociclib in Metastatic HER2-Negative Breast Cancer"; n 40; "Number of participants with neutropenia that leads to permanent treatment discontinuation"; 2028-06-30
NCT02947685
"Randomized, Open Label, Clinical Study of the Targeted Therapy, Palbociclib, to Treat Metastatic Breast Cancer"; n 518; "Progression-free Survival (PFS) as Assessed by Investigator"; 2026-07-31
NCT03304080
"Anastrozole, Palbociclib, Trastuzumab and Pertuzumab in HR-positive, HER2-positive Metastatic Breast"; n 44; "Dose-Limiting Toxicity (DLT)"; 2027-12-31
NCT03944434
"FACILE: FeAsibility of First-line RiboCIclib in OLdEr Patients with Advanced Breast Cancer"; n 116; "Treatment feasibility"; 2025-11-27
NCT04158362
"Endocrine Therapy With Abemaciclib or Chemotherapy as Initial Metastatic Treatment in ER+/HER2- Breast Cancer"; n 180; "Progression-free survival (PFS)"; 2032-06
NCT04469764
"Abemaciclib for the Treatment of Recurrent Ovarian or Endometrial Cancer"; n 32; "Proportion of patients who are progression-free"; 2028-07-01
NCT04553770
"Trastuzumab Deruxtecan Alone or in Combination With Anastrozole for the Treatment of Early Stage HER2 Low, Hormone Receptor Positive Breast Cancer"; n 88; "Pathologic complete response (pCR) rate"; 2026-12-31
NCT04556773
"A Phase 1b Study of T-DXd Combinations in HER2-low Advanced or Metastatic Breast Cancer"; n 138; "Occurrence of adverse events (AEs)- Part 1"; 2027-06-01
recorded 2026-09-01 · last checked 2026-09-04
Q9
Which running trial of Anastrozole could settle lifespan?
NCT02947685 measures Progression-free Survival (PFS) as Assessed by Investigator, reading out 2026-07-31.
26 open trials; n 518; "Randomized, Open Label, Clinical Study of the Targeted Therapy, Palbociclib, to Treat Metastatic Breast Cancer"
Show the evidence
Trial
NCT02947685
"Randomized, Open Label, Clinical Study of the Targeted Therapy, Palbociclib, to Treat Metastatic Breast Cancer"; n 518; "Progression-free Survival (PFS) as Assessed by Investigator"; 2026-07-31
NCT05890287
"A Study of Chidamide Plus Endocrine in Maintenance Treatment of HR+/HER2- Breast Cancer After First-line Chemotherapy"; n 60; "Progression-free survival"; 2026-10-01
NCT02246621
"A Study of Nonsteroidal Aromatase Inhibitors Plus Abemaciclib (LY2835219) in Postmenopausal Women With Breast Cancer"; n 493; "Progression Free Survival (PFS)"; 2026-12
NCT01272037
"Tamoxifen Citrate, Letrozole, Anastrozole, or Exemestane With or Without Chemotherapy in Treating Patients With Invasive RxPONDER Breast Cancer"; n 5018; "Invasive Disease-Free Survival (IDFS)"; 2027-01-08
NCT07024173
"A Phase 3 Study of HRS-8080 Versus Treatment Chosen by Physicians in Locally Advanced and Metastatic Breast Cancer"; n 240; "Progression free survival (PFS) evaluated by the blinded independent central review (BICR)."; 2027-12
NCT02763566
"A Study of Abemaciclib (LY2835219) in Participants With Breast Cancer"; n 463; "Progression Free Survival (PFS) (Abemaciclib + NSAI & Placebo NSAI)"; 2028-03
14 further recorded trials
NCT04964934
"Phase III Study to Assess AZD9833+ CDK4/6 Inhibitor in HR+/HER2-MBC With Detectable ESR1m Before Progression (SERENA-6)"; n 315; "Progression-free survival (PFS) assessed by the Investigator as defined by response evaluation criteria in solid tumors (RECIST version 1.1)"; 2028-09-01
NCT04711252
"A Comparative Study of AZD9833 Plus Palbociclib Versus Anastrozole Plus Palbociclib in Patients With ER-Positive HER2 Negative Breast Cancer Who Have Not Received Any Systemic Treatment for Advanced Disease"; n 1370; "Progression-free survival (PFS) assessed by the Investigator as defined by response evaluation criteria in solid tumors (RECIST) version 1.1"; 2029-02-01
NCT05826964
"Levels of Circulating Tumor DNA as a Predictive Marker for Early Switch in Treatment for Patients With Metastatic (Stage IV) Breast Cancer"; n 24; "Progression-Free Survival 1 (PFS1) Among Participants in Step 2"; 2029-07-31
NCT07391774
"Testing Whether Hormone Therapy With Ribociclib is as Effective as Chemotherapy Followed by Hormone Therapy With Ribociclib for the Treatment of High Anatomic Stage Breast Cancer With Low Recurrence Risk, The RxFINE-Low Trial"; n 1978; "Invasive breast cancer-free survival (iBCFS)"; 2029-07-31
NCT05467891
"Ribociclib And Endocrine Treatment of Physician's Choice for Locoregional Recurrent, Resected Hormone Receptor Positive HER2 Negative Breast Cancer"; n 200; "Recurrence Free Survival (RFS)"; 2029-08-15
NCT01674140
"S1207 Hormone Therapy With or Without Everolimus in Treating Patients With Breast Cancer"; n 1939; "Invasive Disease-Free Survival (IDFS)"; 2030-01
NCT04569747
"A Single Arm Phase II Study of ADjuvant Endocrine Therapy, Pertuzumab, and Trastuzumab for Patients With Anatomic Stage I Hormone Receptor-positive, HER2-positive Breast Cancer"; n 393; "Invasive Disease Free Survival at 3 Years"; 2030-09-01
NCT00310180
"Hormone Therapy With or Without Combination Chemotherapy in Treating Women Who Have Undergone Surgery for Node-Negative Breast Cancer (The TAILORx Trial)"; n 10273; "5-year Disease-free Survival"; 2030-09-30
NCT06072781
"A Study of Avutometinib (VS-6766) + Defactinib (VS-6063) in Recurrent Low-Grade Serous Ovarian Cancer"; n 270; "Progression Free Survival (PFS) per blinded independent central review (BICR)"; 2031-02-09
NCT05891093
"Efficacy and Safety of Fluzoparib Combined With Adjuvant Endocrine Therapy for HR+/HER2- SNF3-subtype Early Breast Cancer (BCTOP-L-A01)"; n 766; "invasive disease free survival (iDFS)"; 2031-05-31
NCT06380751
"Saruparib (AZD5305) Plus Camizestrant or Plus Endocrine Therapy, Compared With CDK4/6 Inhibitor Plus Endocrine Therapy or Plus Camizestrant in HR-Positive, HER2-Negative (IHC 0, 1+, 2+/ ISH Non-amplified), BRCA1, BRCA2, or PALB2m Advanced Breast Cancer"; n 788; "Progression-Free Survival (Arm 1 vs arm 2)"; 2031-12-30
NCT05514054
"A Study of Imlunestrant Versus Standard Endocrine Therapy in Participants With Early Breast Cancer"; n 8000; "Invasive Disease-Free Survival (IDFS)"; 2032-03
NCT04158362
"Endocrine Therapy With Abemaciclib or Chemotherapy as Initial Metastatic Treatment in ER+/HER2- Breast Cancer"; n 180; "Progression-free survival (PFS)"; 2032-06
NCT06492616
"A Study of Elacestrant Versus Standard Endocrine Therapy in Women and Men With ER+,HER2-, Early Breast Cancer With High Risk of Recurrence"; n 4220; "Invasive Breast Cancer-Free Survival (IBCFS)"; 2032-10
Q10
Which 67 trials of Anastrozole posted no result?
Posted no result
67 of 67 completed trials
Registrations
NCT00784862, NCT00004906, NCT00637182, NCT00784680, NCT00004900 and NCT00287534, and 61 more
Completion dates
oldest 1999-03; newest 2024-07-05
Show the evidence
Trial
NCT00784862
1999-03
NCT00004906
2001-06
NCT00637182
2002-10
NCT00784680
2004-04
NCT00004900
2004-08
NCT00287534
2004-09
14 further recorded trials
NCT00635713
2004-09
NCT00814125
2005-12
NCT00181688
2006-03
NCT00286117
2006-05
NCT01155102
2006-05
NCT01155089
2006-06
NCT00241436
2006-11
NCT00437853
2007-02
NCT00638391
2007-03
NCT00784940
2007-04
NCT00327769
2007-09
NCT00467493
2007-09
NCT00049062
2007-10
NCT00082277
2007-10
Q11
At the median, Anastrozole's trials enrolled 93 people — anything larger?
Median enrolment
93
Largest enrolment
16989
Registered trials counted
279
Q12
What do 10605 spontaneous reports say about Anastrozole — 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.
Anastrozole appears in spontaneous reports to regulators. Across the 10 most-reported reaction terms, 10605 reaction mentions were counted: malignant neoplasm progression 1690; fatigue 1443; arthralgia 1387; neutropenia 1377. open-targets-adr · CHEMBL1399 · 2026-06-24
Show the evidence
malignant neoplasm progression
1690
fatigue
1443
arthralgia
1387
neutropenia
1377
metastases to bone
932
disease progression
797
4 more recorded rows
neoplasm progression
787
metastases to liver
747
breast cancer
743
breast cancer metastatic
702
recorded 2026-06-24 · last checked 2026-09-04
Q13
Anastrozole and Cytochrome P450: shared by which compounds?
Cytochrome P450 appear in Anastrozole's recorded interaction sentences, 1 in all. openfda-label+europepmc · 2026-08-20
Interpretation drug_interactions
Show the evidence
Cytochrome P450drug_interactions
7.4 Cytochrome P450 Based on in vitro and in vivo results, it is unlikely that co-administration of anastrozole tablets 1 mg will affect other drugs as a result of inhibition of cytochrome P450 [see Clinical Pharmacology (12.3) ].
recorded 2026-08-20 · last checked 2026-09-04
Q14
Was Anastrozole studied with fasting and exercise?
fasting and exercise are named in Anastrozole's label sentences: "This trial aimed to explore the pharmacokinetics (PK) and safety with bioequivalence of orally administered anastrozole provided by 2 sponsors in healthy volunteers.Two separate open-label, randomized, single-dose, crossover-design studies consisting of a fasting study (n = 23) and a fed study (n =…" openfda-label+europepmc · 2026-08-20
2 recorded statements; fasting, exercise
Show the evidence
fasting
This trial aimed to explore the pharmacokinetics (PK) and safety with bioequivalence of orally administered anastrozole provided by 2 sponsors in healthy volunteers.Two separate open-label, randomized, single-dose, crossover-design studies consisting of a fasting study (n = 23) and a fed study (n = 23, 1 participant withdrew before taking medication) were conducted.
exercise
We hypothesize that AI+WL will be more effective as compared to WL alone in improving the hormonal profile, thus muscle strength and symptoms of HHG (primary outcomes), with no significant adverse effects on lean mass, metabolic profile, and bone mineral density (secondary outcomes). <b>Design:</b> Randomized double-blind placebo-controlled pilot trial. <b>Methods:</b> Twenty-three obese men…
recorded 2026-08-20 · last checked 2026-09-04
Q15
What is recorded about Anastrozole and mTOR?
"We recently reported that the combination of Vistusertib (V, mTOR inhibitor) and Anastrozole (A, aromatase inhibitor) improves the progression-free rate compared to Anastrozole alone." — where Anastrozole and mTOR appear together. Europe PMC · pathway abstract search · 2022-12-24
"We recently reported that the combination of Vistusertib (V, mTOR inhibitor) and Anastrozole (A, aromatase inhibitor) improves the progression-free rate compared to Anastrozole alone."
sirtuin
PMID 36574869
"In vitro, C<sub>2</sub>C<sub>12</sub> myoblasts were treated with H<sub>2</sub>O<sub>2</sub> (oxidative stress inducer), SIRT1 inhibitor EX527, or aromatase inhibitor anastrozole."
PMID 36574869
"Moreover, EX527 or anastrozole treatment exacerbated H<sub>2</sub>O<sub>2</sub>-induced growth inhibition and oxidative stress, and expression downregulation of SIRT1, PGC-1α, Nrf2, and HO-1 in C<sub>2</sub>C<sub>12</sub> cells in vitro."
mTOR
PMID 30622925
"Inhibitors of the mTOR have been tested in different clinical trials; everolimus has been Food and Drug Administration approved for the treatment of oestrogen receptor positive/human epidermal growth factor receptor 2 negative BC patients in combination with exemestane in patients who have progressed to anastrozole or letrozole after the encouraging results coming from BOLERO-2 trial."
PMID 23553037
"Strikingly, combining anastrozole with the highly selective and allosteric Akt inhibitor MK-2206 or with the mTOR inhibitor rapamycin increased sensitivity to this AI in the control cells and was sufficient to overcome resistance and restore sensitivity to endocrine therapy in the resistant cells."
IGF-1
PMID 22102688
"No change was observed in IGF-1, IGFBP-3, and breast cytology.We showed a significant modulation of IGFBP-1 levels with six months anastrozole."
PMID 18451180
"Anastrozole plus fulvestrant from the beginning or in sequence was associated with down-regulation of signaling proteins involved in the development of hormonal resistance such as insulin-like growth factor type I receptor beta, mitogen-activated protein kinase (MAPK), p-MAPK, AKT, mammalian target of rapamycin (mTOR), p-mTOR, and estrogen receptor alpha compared with tumors treated with…"
PMID 11983488
"We evaluated total IGF-1, IGF-2, IGF binding protein (IGFBP)-1 and IGFBP-3 in the blood of 34 postmenopausal advanced breast cancer patients (median age 63 years, range 41-85) treated with anastrozole, a non-steroidal structure aromatase inhibitor (NSS-AI)."
recorded 2022-12-24 · last checked 2026-09-04
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