This page shows what was measured, who it was measured in, and what that does not settle.
What Guanfacine does in the body
Attention Deficit Hyperactivity Disorder (ADHD) as monotherapy and as adjunctive therapy to stimulant medications [see Clinical Studies (14
From the FDA-approved label: Guanfacine is a central alpha 2A -adrenergic receptor agonist. Guanfacine is not a central nervous system (CNS) stimulant. The mechanism of action of guanfacine in ADHD is not known.
What happened in people
RNAWiki has not yet published a reviewed conclusion for this use.
§ A fixed RNAWiki sentence
Where this came from
Wording RNAWiki always uses, not a finding about this substance.
No reviewed claim names a result for any goal on this record.
No source is stored against this line.
The limit that matters most
Not recorded.
Where it acts
Not recorded.
Kind of result
No result is published, so no kind of result applies yet
Supervision
RNAWiki has not recorded a supervision or regulatory status for this substance.
What the registries record it as
The substance registry classes this as chemical.
FDA substance registry · 30OMY4G3MK · read 2026-08-29
Its recorded molecular formula is C9H9Cl2N3O·HCl, weighing 282.55.
US prescribing information · 145a191d-9049-4014-9c42-503fdde063dc · read 2026-08-30
Where each sentence above came from
No recorded sentence describes the change this makes in a way that stands on its own. The page opens with what it is taken for instead, and the recorded explanation follows below.
Shown as the opening line on this page.
No statement of the main limit is recorded.
The four opening statements run to 64 words.
Words this page uses
Four words worth knowing first
Chosen from what this page shows, with each one explained before the word it depends on.
Biomarker
A biomarker is a number from a test that stands in for something about health.
A picture of it, and where the picture fails
A biomarker is like a fuel gauge.
Where that stops being true. A gauge is wired to the tank. Many biomarkers are only loosely tied to health.
What people get wrong. A better number is read as a better life. Several medicines improved a number and helped nobody.
A measurable indicator used as a substitute for a clinical outcome of interest.
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.
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
Pain
∅Nothing in the sources checkedNo registered study lists a life outcome for this goal.
∅Nothing in the sources checkedNo registered study lists a performance measure for this goal.
…Waiting for a reviewer3 registered symptom measure.
∅Nothing in the sources checkedNo registered study lists a test result for this goal.
∅Nothing in the sources checkedNo registered study lists a body-step measure for this goal.
—Not recordedHarms were not a registered measure for this goal.
—Not recordedNo finished study window is recorded.
…Waiting for a reviewerWho was studied is listed further down the page.
Healthy ageing
…Waiting for a reviewer2 registered study measure of this kind. No reviewed result yet.
∅Nothing in the sources checkedNo registered study lists a performance measure for this goal.
∅Nothing in the sources checkedNo registered study lists a symptom measure for this goal.
∅Nothing in the sources checkedNo registered study lists a test result for this goal.
∅Nothing in the sources checkedNo registered study lists a body-step measure for this goal.
—Not recordedHarms were not a registered measure for this goal.
—Not recordedNo finished study window is recorded.
…Waiting for a reviewerWho was studied is listed further down the page.
Focus
∅Nothing in the sources checkedNo registered study lists a life outcome for this goal.
∅Nothing in the sources checkedNo registered study lists a performance measure for this goal.
∅Nothing in the sources checkedNo registered study lists a symptom measure for this goal.
∅Nothing in the sources checkedNo registered study lists a test result for this goal.
∅Nothing in the sources checkedNo registered study lists a body-step measure for this goal.
—Not recordedHarms were not a registered measure for this goal.
—Not recordedNo finished study window is recorded.
…Waiting for a reviewerWho was studied is listed further down the page.
Which registered measures put each goal on this table
all cause hospitalization or all cause mortality; all cause mortality
Focus
matrics consensus cognitive battery
Sorted by fixed word lists, version v1. A name the rules do not recognise stays unsorted rather than moving to the nearest column.
What each mark on this table means
∅ Nothing in the sources checked
No registered study lists a life outcome for this goal.
… Waiting for a reviewer
3 registered symptom measure.
— Not recorded
Harms were not a registered measure for this goal.
What happened in people◇Read from sources, not yet reviewed
What happened in people
Each card is one study: the exact question it asked, who was in it, and whether it showed what it set out to show.
Change from baseline in trough sitting systolic and diastolic blood pressure measured by sphygmomanometry
✗ The study did not show it
Who was studied
NCT00389779
How many people
849
Study design
Phase 3
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Result not recorded on this page
Repeated elsewhere
Unreplicated
What this does not prove. A study that did not show an effect does not show that no effect exists anywhere.
The limits of this study, and where it came from
Main limit. No limitation is recorded for this study.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
openFDA Drugs@FDA · a recorded source, not a stored snapshot
openFDA NDC Directory · a recorded source, not a stored snapshot
openFDA SPL label · a recorded source, not a stored snapshot
PubChem PUG-REST · a recorded source, not a stored snapshot
Change from baseline in mean 24-hour systolic and diastolic ambulatory blood pressure
✗ The study did not show it
Who was studied
NCT00389675
How many people
661
Study design
Phase 3
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Result not recorded on this page
Repeated elsewhere
Unreplicated
What this does not prove. A study that did not show an effect does not show that no effect exists anywhere.
The limits of this study, and where it came from
Main limit. No limitation is recorded for this study.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
openFDA Drugs@FDA · a recorded source, not a stored snapshot
openFDA NDC Directory · a recorded source, not a stored snapshot
openFDA SPL label · a recorded source, not a stored snapshot
PubChem PUG-REST · a recorded source, not a stored snapshot
Percentage of Participants With Treatment Failures During the Double-Blind Randomized-Withdrawal Phase
✗ The study did not show it
Who was studied
NCT01081145
How many people
528
Study design
Phase 3
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Result not recorded on this page
Repeated elsewhere
Unreplicated
What this does not prove. A study that did not show an effect does not show that no effect exists anywhere.
The limits of this study, and where it came from
Main limit. No limitation is recorded for this study.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
openFDA Drugs@FDA · a recorded source, not a stored snapshot
openFDA NDC Directory · a recorded source, not a stored snapshot
openFDA SPL label · a recorded source, not a stored snapshot
PubChem PUG-REST · a recorded source, not a stored snapshot
The Vanderbilt Parent Rating Scale
✗ The study did not show it
Who was studied
NCT05916339
How many people
500
Study design
Phase 4
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Result not recorded on this page
Repeated elsewhere
Unreplicated
What this does not prove. A study that did not show an effect does not show that no effect exists anywhere.
The limits of this study, and where it came from
Main limit. No limitation is recorded for this study.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
openFDA Drugs@FDA · a recorded source, not a stored snapshot
openFDA NDC Directory · a recorded source, not a stored snapshot
openFDA SPL label · a recorded source, not a stored snapshot
PubChem PUG-REST · a recorded source, not a stored snapshot
Change From Baseline in Attention Deficit Hyperactivity Disorder Rating Scale-fourth Edition (ADHD-RS-IV) Total Score at Week 8 - Last Observation Carried Forward (LOCF)
✗ The study did not show it
Who was studied
NCT00734578
How many people
461
Study design
Phase 3
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Result not recorded on this page
Repeated elsewhere
Unreplicated
What this does not prove. A study that did not show an effect does not show that no effect exists anywhere.
The limits of this study, and where it came from
Main limit. No limitation is recorded for this study.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
openFDA Drugs@FDA · a recorded source, not a stored snapshot
openFDA NDC Directory · a recorded source, not a stored snapshot
openFDA SPL label · a recorded source, not a stored snapshot
PubChem PUG-REST · a recorded source, not a stored snapshot
Part A: Change From Baseline in the Cambridge Neuropsychological Test Automated Battery (CANTAB) Reaction Time (RTI) Task at Week 18
✗ The study did not show it
Who was studied
NCT04085172
How many people
396
Study design
Phase 4
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Result not recorded on this page
Repeated elsewhere
Unreplicated
What this does not prove. A study that did not show an effect does not show that no effect exists anywhere.
The limits of this study, and where it came from
Main limit. No limitation is recorded for this study.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
openFDA Drugs@FDA · a recorded source, not a stored snapshot
openFDA NDC Directory · a recorded source, not a stored snapshot
openFDA SPL label · a recorded source, not a stored snapshot
PubChem PUG-REST · a recorded source, not a stored snapshot
What we know
RNAWiki holds 6 written-up human studies for this substance, each with the question it asked.
How we know it
Each card names the study, the number of people and what the study set out to measure.
What this does not prove
These summaries were written by a person and have not been signed off as reviewed claims.
Why it matters
A study that failed is as informative as one that worked, and both are here.
What we still do not know
No reviewed claim exists, so no exact population, effect size or interval is published yet.
What 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.2 registered measures of this kind. No reviewed result.
□What a body can do day to dayNo evidence recorded. Walking, dressing, breathing, recovering.No registered study measures this.
□Measured performanceNo evidence recorded. How much was lifted, how far was run, how fast.No registered study measures this.
■Symptoms and quality of lifeEvidence recorded. Pain, tiredness, mood, sleep, as the person rated it.4 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.2 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.
□AnimalsNo evidence recorded. Mice, rats, dogs. Useful for ideas, not proof about people.No animal record is stored.
□Cells in a dishNo evidence recorded. Cells or chemistry on a bench, far from a whole body.No cell or bench record is stored.
□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 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.
cocaine craving
numeric pain
numeric pain rating scale
pain level
Measured
Things only a test, a scale or a device shows.
decrease in supine systolic blood pressure
maximum concentration as measured by pk sampling
Meaningful
Things that change how a life goes, not only a number.
all cause hospitalization or all cause mortality
all cause mortality
A registered study says what someone planned to measure. It does not say what they found. A number moving is not the same as a life going better. The two are shown apart here.
Felt, but not shown to help. A person notices a change. No study showed it leads anywhere good.
Measured, but not felt. A number moves. The person notices nothing. Both can be true.
Measured, but not shown to matter. A number moves in the good direction. Nobody showed that lives went better.
Matters, but takes years. The result that counts may take longer than anyone would keep watching.
These are harms, study-process measures, or names the rules did not recognise. They are shown rather than dropped.
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.
Guanfacine extended-release tablets are indicated for the treatment of Attention Deficit Hyperactivity Disorder (ADHD) as monotherapy and as adjunctive therapy to stimulant medications [see Clinical Studies (14 )].
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 efficacy of guanfacine extended-release tablets in pediatric patients less than 6 years of age have not been established.”
US prescribing information · 145a191d-9049-4014-9c42-503fdde063dc · read 2026-08-30
On older people, the label states: “The safety and efficacy of guanfacine extended-release tablets in geriatric patients have not been established.”
US prescribing information · 145a191d-9049-4014-9c42-503fdde063dc · read 2026-08-30
On people who are pregnant, the label states: “Risk Summary Available data with guanfacine over decades of 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 · 145a191d-9049-4014-9c42-503fdde063dc · read 2026-08-30
On people who are breastfeeding, the label states: “Risk Summary There are no data on the presence of guanfacine in human milk or the effects on the breastfed infant.”
US prescribing information · 145a191d-9049-4014-9c42-503fdde063dc · read 2026-08-30
On people with reduced liver function, the label states: “It may be necessary to reduce the dosage in patients with significant impairment of hepatic function [see Clinical Pharmacology ( 12.3 )].”
US prescribing information · 145a191d-9049-4014-9c42-503fdde063dc · read 2026-08-30
On people with reduced kidney function, the label states: “It may be necessary to reduce the dosage in patients with significant impairment of renal function [see Clinical Pharmacology ( 12.3 )].”
US prescribing information · 145a191d-9049-4014-9c42-503fdde063dc · read 2026-08-30
Where the result stopped carrying
This is a scope explorer, not a diagnosis engine.
It shows who was studied so you can see whether people similar to you were included.
RNAWiki cannot tell whether a study fits you. It can show who was in it.
What it would be like to 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
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The form and route recorded on this substance.
No source is stored against this line.
Who oversees it
RNAWiki has not recorded a supervision or regulatory status for this substance.
❝ Quoted from a source
Where this came from
Copied from a source RNAWiki stored, with the source named.
No register row and no identity class settled the question.
No source is stored against this line.
What is in the pack
Sold as tablet, tablet, extended release, given by the oral route.
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
Recorded notes on how this is sold and what that means for what is in the pack.
No source is stored against this line.
Where it is registered
Regulatory records are listed in the technical disclosure at the foot of this page.
# Counted from records
Where this came from
A count of rows RNAWiki holds. It describes our records, not your body.
Register entries are stored per jurisdiction and shown with their dates.
No source is stored against this line.
Why people stop
Not recorded.
∅ Nothing recorded
Where this came from
RNAWiki holds nothing here and says so rather than guessing.
No record of why people stopped taking it is stored for this substance.
No source is stored against this line.
What it would be like to take∅Nothing found in the sources checked
What can go wrong
Sorted by where each line came from. A regulator's label and a report somebody sent in are not the same kind of fact.
∅Nothing found in the sources checked
No harm is recorded against this substance in the sources RNAWiki checked. Finding nothing is not the same as showing there is nothing.
The sources listed were searched and held nothing. That is not the same as nothing existing.
Reports sent to a regulator
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.
Guanfacine appears in spontaneous reports to regulators. Across the 10 most-reported reaction terms, 793 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
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The form used in the studies cited on this page.
No source is stored against this line.
What is sold
Not recorded.
∅ Nothing recorded
Where this came from
RNAWiki holds nothing here and says so rather than guessing.
Nothing further is recorded about which forms are sold.
No source is stored against this line.
What is recorded as being sold
138 products list this as an active ingredient in the United States drug directory. 138 of them contain it and nothing else.
FDA National Drug Code directory · 72162-1798 · read 2026-08-29
They are sold as powder, tablet and tablet, extended release, taken oral.
FDA National Drug Code directory · 72162-1798 · read 2026-08-29
The regulator's established pharmacologic class for it is adrenergic alpha2-agonists [moa] and central alpha-2 adrenergic agonist [epc].
FDA National Drug Code directory · 72162-1798 · read 2026-08-29
63 published labels name it as an active ingredient. 63 of them describe this substance alone, which is where its own label text on this page comes from.
US prescribing information · 4973deb3-57ec-1ef3-e063-6294a90aa035 · read 2026-08-29
Those labels are classed as human prescription drug.
US prescribing information · 4973deb3-57ec-1ef3-e063-6294a90aa035 · read 2026-08-29
Guanfacine is oral at 3 DOSAGE FORMS AND STRENGTHS 1 mg extended-release tablets., recorded as fda label in effect 2026-01-14 in the United States.
US prescribing information · 145a191d-9049-4014-9c42-503fdde063dc · read 2026-08-30
Recorded price in US: 0.14423–0.27213 USD per one unit as the pricing file counts it — a tablet, capsule, patch or single item, across 31 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 Guanfacine 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
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 Guanfacine 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.
How many documents were read
58 documents were read for this substance.
RNAWiki source record
24 of them state the same halfLife, and they agree.
RNAWiki source record
24 of them state the same volumeOfDistribution, and they agree.
RNAWiki source record
Where else this substance is registered
FDA substance identifier (UNII)
30OMY4G3MK
CAS registry number
29110-47-2
PubChem compound
3519
ChEMBL
CHEMBL862
WHO international nonproprietary name list entry
3999
RxNorm concept
40114
EMA substance identifier
100000084474
European Chemicals Agency number
249-442-8
DrugBank
DB01018
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
27 approved applications cover products containing this substance. The earliest was NDA019032, approved 19861027 to PROMIUS PHARMA.
This order is fixed in code and does not count clicks or time on the page.
What is not here
6 questions this page could not answer
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Recorded evidence blocks (13)
Q1
What did Guanfacine's largest trial (22213 people) and its longest (16 years) measure?
22213 people in Guanfacine's largest registered study, 16 years in its longest registered window, measuring All-Cause-Hospitalization or All-Cause Mortality. ClinicalTrials.gov · 2026-09-01
21 phase4, 19 phase2, 14 phase3, 12 na, 8 phase1, 5 na or unstated, 1 early phase1; NCT00223717; 2017-01. Last human test completed 2025, NCT04742673.
Interpretation These counts include studies where Guanfacine 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
phase4
21
phase2
19
phase3
14
na
12
phase1
8
na or unstated
5
2 more recorded rows
early phase1
1
Last recorded human testNCT04742673
2025-11-30
recorded 2026-09-01 · last checked 2026-09-04
Q2
Guanfacine was tested only in human — what did it show?
9 recorded entries; human; also "SPD503 (2 mg)", "SPD503 (3 mg)", "SPD503 (4 mg)"
Show the evidence
human
NCT00150618
SPD503 (1 mg)
NCT00150618
SPD503 (2 mg)
NCT00150618
SPD503 (3 mg)
NCT00150618
SPD503 (4 mg)
NCT00152009
SPD503 (Guanfacine hydrochloride) (2 mg)
NCT01681264
Guanfacine 1mg
3 more recorded rows
humanNCT01681264
Guanfacine 2mg
humanNCT02164422
Guanfacine 3mg/day
humanNCT02164422
Guanfacine 1.5mg/day
recorded 2026-09-01 · last checked 2026-09-04
Q5
More Guanfacine was worse in human: at what point?
U-shaped in human: "With guanfacine the maximal fall of blood pressure was comparable to that obtained with the 5-HT1A receptor ligands; however, in contrast to the latter, the dose-response curve was U-shaped, the highest dose eliciting a pressor effect with reversal of the vasodilatation." Europe PMC · dose-response search · 2024-04-09
6 recorded sentences naming Guanfacine; U-shaped, dose-response
Show the evidence
U-shapedPMID 2568144
"With guanfacine the maximal fall of blood pressure was comparable to that obtained with the 5-HT1A receptor ligands; however, in contrast to the latter, the dose-response curve was U-shaped, the highest dose eliciting a pressor effect with reversal of the vasodilatation."
dose-response
PMID 38591725
"The dose-response curves of guanfacine, dexmedetomidine, and lidocaine were constructed and drug-drug interactions were analyzed by the ED<sub>50</sub> isobologram."
PMID 2568144
"A weak tendency towards vasodilatation was found in the kidneys where the dose-response curve was bell-shaped for guanfacine."
PMID 2903226
"In contrast, guanfacine produced a dose-response profile opposite to that seen with clonidine: low doses improved memory without inducing hypotension or sedation, while the memory-impairing, hypotensive, and sedating properties of the drug were observed at higher doses."
PMID 2868907
"After chronic imipramine treatment (20 mg/kg i.p., once daily for 14 days) the dose-response curve of the isolated rat anococcygeal muscle to phenylephrine shifted to the left, and furthermore, the -log KA value (affinity) for phenylephrine was significantly increased without affecting the affinity for guanfacine."
PMID 2868907
"On the other hand, such treatment caused a shift to the right of the dose-response curve to guanfacine on aortic strips and the affinity of the alpha-adrenoceptor for guanfacine was lowered without any accompanying changes in the affinity value for phenylephrine."
recorded 2024-04-09 · last checked 2026-09-04
Q6
Could one person measure Guanfacine's effect on hyperactivity impulsiveness and distractibility?
Hyperactivity impulsiveness and distractibility: measured in Guanfacine's trials.
Interpretation hyperactivity impulsiveness and distractibility is the recorded endpoint.
Show the evidence
biomarkers
hyperactivity impulsiveness and distractibility; 2026-09-01
decrease in supine systolic blood pressure; 2026-09-01
estimated glomerular filtration rate; 2026-09-01
adhd iv rating scale; 2026-09-01
cocaine craving; 2026-09-01
electrocardiogram results at tmax on day 6; 2026-09-01
14 more recorded rows
biomarkers
latency to initiate ad lib smoking session; 2026-09-01
electrocardiogram result at final assessment; 2026-09-01
biomarkers
yale global tic severity scale; 2026-09-01
biomarkers
numeric pain; 2026-09-01
biomarkers
snap iv teacher and parent rating scale; 2026-09-01
human trials at or under30
21
Not recorded for this substance
a recorded half-life
smallest human trial
0; NCT03258476; PHASE4; the smallest recorded human enrolment at or below 30; the registry states no direction of its result; WITHDRAWN
Q7
Which of aberrant behavior checklist hyperactivity subscale, absorption rate constant as measured by pk sampling and adhd iv rating scale did Guanfacine's trials measure?
aberrant behavior checklist hyperactivity subscale, absorption rate constant as measured by pk sampling and adhd iv rating scale lead 40 outcome terms across Guanfacine's trials. ClinicalTrials.gov · 2026-09-01
adhd iv rating scale, cocaine craving, electrocardiogram results at tmax on day 6, latency to initiate ad lib smoking session, cmax of d methylphenidate and auc of d methylphenidate follow.
Alcohol Consumption; Clearance (CL) or apparent oral clearance (CL/F) as measured by PK sampling; latest 2030-07
Show the evidence
Trial
NCT03764098
"Mechanistic Evaluation of Guanfacine on Drinking Behavior in Women and Men With Alcohol Use Disorders"; n 160; "Alcohol Consumption"; 2026-08-31
NCT04278404
"Pharmacokinetics, Pharmacodynamics, and Safety Profile of Understudied Drugs Administered to Children Per Standard of Care (POPS)"; n 5000; "Clearance (CL) or apparent oral clearance (CL/F) as measured by PK sampling"; 2026-12
NCT05710627
"Evaluation of TENEX for Greater Trochanteric Pain Syndrome (GTPS)"; n 150; "Pain Level"; 2028-12
NCT05957848
"Guanfacine Extended-release for Adolescents With Cannabis Use"; n 100; "Efficacy - change from baseline in cannabis use frequency following monitored abstinence"; 2026-06-30
NCT06408246
"ACE-D Aim 3 Clinical Cognitive Trial to Enhance Translation in Depression"; n 162; "Remission of depressive symptoms"; 2029-02-01
NCT06629259
"Guanfacine for Alcohol Use Disorder (AUD)"; n 200; "Change in % number of days drinking"; 2029-09-07
2 further recorded trials
NCT07300956
"Treating Young Children With Attention Deficit Hyperactivity Disorder"; n 370; "Clinical Global Impression-Improvement"; 2030-07
NCT07757555
"Guanfacine and Cromolyn Sodium for POTS: The DBPOTS Trial"; n 25; "Change in Physical Function as Measured by the PROMIS® Physical Function Scale"; 2028-02-02
recorded 2026-09-01 · last checked 2026-09-04
Q9
Which running trial of Guanfacine could settle function?
NCT07757555 measures Change in Physical Function as Measured by the PROMIS® Physical Function Scale, reading out 2028-02-02.
1 open trial; n 25; "Guanfacine and Cromolyn Sodium for POTS: The DBPOTS Trial"
Show the evidence
TrialNCT07757555
"Guanfacine and Cromolyn Sodium for POTS: The DBPOTS Trial"; n 25; "Change in Physical Function as Measured by the PROMIS® Physical Function Scale"; 2028-02-02
Q10
Which 13 trials of Guanfacine posted no result?
Posted no result
13 of 13 completed trials
Registrations
NCT00004376, NCT00018603, NCT00389779, NCT01146002, NCT03662763 and NCT01177306, and 7 more
Completion dates
oldest 2000-06; newest 2023-12-16
Show the evidence
Trial
NCT00004376
2000-06
NCT00018603
2002-10
NCT00389779
2009-08
NCT01146002
2013-02
NCT03662763
2013-12
NCT01177306
2014-05
7 further recorded trials
NCT00585754
2016-06
NCT00223717
2017-01
NCT02524899
2017-01-10
NCT04113551
2020-01-10
NCT04467931
2020-12-31
NCT02136147
2022-06
NCT05657860
2023-12-16
Q11
At the median, Guanfacine's trials enrolled 70 people — anything larger?
Median enrolment
70
Largest enrolment
22213
Registered trials counted
77
Q12
What do 793 spontaneous reports say about Guanfacine — 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.
Guanfacine appears in spontaneous reports to regulators. Across the 10 most-reported reaction terms, 793 reaction mentions were counted: somnolence 135; bradycardia 100; electrocardiogram qt prolonged 93; hypotension 92. open-targets-adr · CHEMBL1200494 · 2026-06-24
Show the evidence
somnolence
135
bradycardia
100
electrocardiogram qt prolonged
93
hypotension
92
aggression
83
syncope
73
4 more recorded rows
dizziness
70
suicidal ideation
56
agitation
48
toxicity to various agents
43
recorded 2026-06-24 · last checked 2026-09-04
Q13
Guanfacine and CYP3A4, OCT1 and MATE1: shared by which compounds?
CYP3A4, OCT1 and MATE1 appear in Guanfacine's recorded interaction sentences, 10 in all. openfda-label+europepmc · 2026-08-30
Interpretation pharmacokinetics
Show the evidence
CYP1A2pharmacokinetics
In pooled human hepatic microsomes, guanfacine did not inhibit the activities of the major cytochrome P450 isoenzymes (CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6 or CYP3A4/5); guanfacine is also not an inducer of CYP3A, CYP1A2 and CYP2B6.
CYP2B6pharmacokinetics
In pooled human hepatic microsomes, guanfacine did not inhibit the activities of the major cytochrome P450 isoenzymes (CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6 or CYP3A4/5); guanfacine is also not an inducer of CYP3A, CYP1A2 and CYP2B6.
CYP2C19pharmacokinetics
In pooled human hepatic microsomes, guanfacine did not inhibit the activities of the major cytochrome P450 isoenzymes (CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6 or CYP3A4/5); guanfacine is also not an inducer of CYP3A, CYP1A2 and CYP2B6.
CYP2C8pharmacokinetics
In pooled human hepatic microsomes, guanfacine did not inhibit the activities of the major cytochrome P450 isoenzymes (CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6 or CYP3A4/5); guanfacine is also not an inducer of CYP3A, CYP1A2 and CYP2B6.
CYP2C9pharmacokinetics
In pooled human hepatic microsomes, guanfacine did not inhibit the activities of the major cytochrome P450 isoenzymes (CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6 or CYP3A4/5); guanfacine is also not an inducer of CYP3A, CYP1A2 and CYP2B6.
CYP2D6pharmacokinetics
In pooled human hepatic microsomes, guanfacine did not inhibit the activities of the major cytochrome P450 isoenzymes (CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6 or CYP3A4/5); guanfacine is also not an inducer of CYP3A, CYP1A2 and CYP2B6.
CYP3A4
pharmacokinetics
In vitro studies with human liver microsomes and recombinant CYP's demonstrated that guanfacine was primarily metabolized by CYP3A4.
pharmacokinetics
In pooled human hepatic microsomes, guanfacine did not inhibit the activities of the major cytochrome P450 isoenzymes (CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6 or CYP3A4/5); guanfacine is also not an inducer of CYP3A, CYP1A2 and CYP2B6.
pharmacokinetics
Guanfacine is a substrate of CYP3A4/5 and exposure is affected by CYP3A4/5 inducers/inhibitors.
pharmacokinetics
Drug Interaction Studies Guanfacine is primarily metabolized by CYP3A4 and its plasma concentrations can be affected significantly by CYP3A4 inhibitors or inducers ( Figure 2 ).
recorded 2026-08-30 · last checked 2026-09-04
Where it is registeredIdentifiers, relations and other names
ClinicalTrials.gov — US Government work · Europe PMC — metadata only, under the recorded legal gate · Open Targets 26.06 — CC0 · derived from this page's own recorded fields; no external licence · mixed register set; per-register licences in docs/specs/corpus-20k-sources.md · openFDA / DailyMed — US Government work
✗ required summary fields resolved: 5 required field(s) not terminal: Why people use it, Best-supported result, Most important common problem, Biggest unanswered question, Human evidence
✓ public claims reviewed: 0 reviewed claim(s); drafts are never rendered
✓ source coverage passed: 9 source rows
✓ no critical contamination: no quarantine open
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