This page shows what was measured, who it was measured in, and what that does not settle.
What Oxybutynin does in the body
The bladder wall contracts when acetylcholine lands on muscarinic receptors in it, and oxybutynin blocks those receptors so the contraction is blunted.
It is not selective about which muscarinic receptors it blocks, and it is not selective about which organ it does it in. When the tablet is swallowed, the liver converts much of it into a second compound, N-desethyloxybutynin, which is about as active as the drug itself and reaches the salivary glands in quantity — which is why the immediate-release tablet dries out roughly seven patients in ten. Every newer version of this drug, from the once-daily tablet to the skin patch, is an attempt to get the drug into the body without going through that conversion step.
Why people take it. An overactive bladder — sudden urgency, going far too often, and leaking — treated with the oldest and cheapest drug available for it
What happened in people
Dry mouth in 72.4% on immediate-release oxybutynin against 34.9% on extended release, with dizziness 16.6% against 5.0% and somnolence 14.1% against 5.6%
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The recorded finding that sits closest to something a person would notice. Written into the record, not signed off, and it carries no population or interval.
Oxybutynin gel -3.0 (SD 2.73) against placebo gel -2.5 (SD 3.06); the results record does not carry a p-value for the primary comparison
Repeated elsewhere
Unreplicated
What this does not prove. Meeting one endpoint in one population does not carry to other goals or other people.
The limits of this study, and where it came from
Main limit. The placebo gel arm removed 2.5 incontinence episodes a day. That is the largest placebo response of any trial on this page and it leaves a drug-attributable margin of 0.5 episodes.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral immediate-release tablet and syrup, oral extended-release tablet, transdermal system, and topical gel
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
Percentage reduction in incontinence episodes from bladder diaries
✗ The study did not show it
Who was studied
Behavioural versus drug treatment for urge incontinence (Burgio 1998)
How many people
197
Study design
Randomised controlled trial, three arms, 8 weeks per treatment phase
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Behavioural 80.7% versus drug 68.5%, P=.04; both versus placebo 39.4%, P<.001 and P=.009
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. 75.5% of the oxybutynin group wanted to change to another treatment, the same proportion as in the placebo group, against 14.0% of the behavioural group. `endpoint met: false` records that the drug arm lost the head-to-head comparison, not that the trial failed.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral immediate-release tablet and syrup, oral extended-release tablet, transdermal system, and topical gel
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
Percentage of participants who did not stop use when they developed a new symptom named in the labelling or when their condition worsened
✗ The study did not show it
Who was studied
Oxytrol Transdermal System Actual Use Study (NCT04534491)
How many people
855
Study design
Phase 3 single-group open-label consumer actual-use study
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
14.4% (95% CI 12.0 to 17.2) pre-mitigation and 3.4% (2.2 to 5.0) post-mitigation of 727 evaluable participants
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. Patch misuse — wrong duration or more than one applied at once — was 51.7% pre-mitigation and 21.2% post-mitigation. Of 324 continuing despite concerning symptoms, 16 were assessed as at medical risk and 24 at possible risk.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral immediate-release tablet and syrup, oral extended-release tablet, transdermal system, and topical gel
Interval reported. 95% CI 12
Written into the record, not signed off as a reviewed claim.
Change in weekly urge urinary incontinence episodes against placebo
✓ The study showed what it set out to show
Who was studied
Oxybutynin extended-release registration programme (US label, Study 1)
How many people
774
Study design
Randomised double-blind placebo-controlled
Compared against
A dummy treatment
Kind of result
A number that stands in for health
What was found
Urge incontinence episodes fell 15.8 per week on extended-release oxybutynin against 7.6 on placebo; the label reports the arm values without a p-value in the extracted text
Repeated elsewhere
Partially Replicated
What this does not prove. Meeting one endpoint in one population does not carry to other goals or other people.
The limits of this study, and where it came from
Main limit. The sample size given is the pooled safety population of 774 for the extended-release arm reported in the Adverse Reactions table, not a per-study randomised total. No equivalent placebo-controlled trial exists for the immediate-release tablet.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral immediate-release tablet and syrup, oral extended-release tablet, transdermal system, and topical gel
Interval reported. Not recorded in this summary
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 it changes in the body◇Read from sources, not yet reviewed
The path through the body
From what a person takes to what changes. A solid line is a step measured in people. A dashed line is a step nobody has measured that way.
Where a source records it acting
Bladder and urinary tract: Relaxes bladder smooth muscle; exerts a direct antispasmodic effect on smooth muscle and inhibits the muscarinic action of acetylcholine on smooth muscle
US prescribing information · 02ff3be7-fc5c-4b91-8c67-ecdf6e19c42a · read 2026-08-28
Start
Oxybutynin
What a person takes: Oral immediate-release tablet and syrup, oral extended-release tablet, transdermal system, and topical gel.
The measurement behind this step
Four routes for one molecule, and the reason for all of them is the same: avoiding or reducing first-pass conversion to N-desethyloxybutynin. The extended-release tablet slows absorption; the transdermal system and topical gel bypass the gut and liver entirely. None of them changes the drug. The extended-release tablet is swallowed whole and its non-absorbable shell may be visible in the stool, which is expected rather than a treatment failure.
Getting in
Swallowed — and immediately half-converted into something else
A tablet goes through the liver before it reaches the rest of the body, and the liver turns much of this drug into a second compound that is just as active. That second compound is the source of most of the dry mouth.
╌╌Measured in animals. A result in animals says what to test next. It does not say what happens in people.
The measurement behind this step
Extensive first-pass metabolism, principally by CYP3A4, generates N-desethyloxybutynin, which the label describes as having pharmacological activity similar to the parent in vitro. Extended-release, transdermal and topical gel formulations all exist to alter the parent-to-metabolite ratio rather than to alter the molecule. The extended-release tablet halves the dry-mouth rate on that basis alone.
It reaches the bladder wall — and everywhere else, including the brain
The target is on the outside of the muscle cell, so nothing needs to be carried inside. But this particular molecule is fat-soluble and uncharged, so it also passes into the brain more readily than newer drugs in its class.
──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
Muscarinic receptors are plasma-membrane G-protein-coupled receptors with an outward-facing binding pocket; no transporter step is required. Oxybutynin is a lipophilic tertiary amine, in contrast to the quaternary, permanently charged trospium, and blood-brain barrier penetration follows from that difference in physical chemistry. This is the structural basis of the class cognitive concern, and the reason oxybutynin is the molecule most often named in it.
It blocks acetylcholine at every muscarinic receptor it meets
Newer drugs try to prefer the receptor subtype the bladder uses. This one does not distinguish. It blocks the signal in the bladder, the salivary gland, the gut and the eye at the same time.
╌╌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
Non-selective competitive muscarinic antagonism, with the R-enantiomer of the racemate carrying the activity. The label additionally preserves a direct smooth-muscle relaxant claim alongside receptor blockade, wording that dates from an era when antispasmodics were characterised functionally rather than by receptor pharmacology.
The calcium signal that drives the squeeze is blunted
A bladder contraction needs a burst of calcium inside the muscle cell. With the receptors occupied, that burst is smaller and the involuntary squeeze during filling is weaker.
╌╌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
Loss of M3-Gq/11 coupling reduces phospholipase C activity, inositol trisphosphate falls, sarcoplasmic reticulum calcium release drops and myosin light-chain phosphorylation declines. The identical cascade is interrupted in salivary acinar cells, where the consequence is not relaxation but a failure to secrete — which is what a 72.4% dry-mouth rate looks like at the molecular level.
The once-daily tablet removes roughly one more leak a day than placebo. It costs about eight cents. Those two facts together are why it is still one of the most prescribed drugs in the indication fifty years after approval.
╌╌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
Urge incontinence episodes fell 15.8 per week on extended-release oxybutynin against 7.6 on placebo, equivalent to 2.26 against 1.09 per 24 hours. Median United States pharmacy acquisition cost is US$0.0817 per unit across ninety-two listed products. The cost of that effect is a dry-mouth rate of 34.9% on the extended-release form and 72.4% on the immediate-release one, plus membership of the drug class with the strongest observational cognitive signal.
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 is missing or unclear◇Read from sources, not yet reviewed
Were people like you studied?
RNAWiki cannot tell whether a study fits you. It can show who was in it, and where the result stops carrying.
Who was studied
People similar to this profile were included.
Anyone for whom cost is the deciding factor, which in practice means a very large number of older adults — the group in whom the anticholinergic-burden evidence is strongest and in whom this particular molecule crosses into the brain most readily.
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: “The safety and efficacy of oxybutynin chloride extended-release tablets were studied in 60 children in a 24 week, open-label, non-randomized trial.”
US prescribing information · c042bf06-79a3-4dc7-ae05-3ef3cfae9d44 · read 2026-08-30
On older people, the label states: “The rate and severity of anticholinergic effects reported by patients less than 65 years old and those 65 years and older were similar.”
US prescribing information · c042bf06-79a3-4dc7-ae05-3ef3cfae9d44 · read 2026-08-30
On people who are pregnant, the label states: “Risk Summary There are no adequate data on oxybutynin chloride extended-release tablets use in pregnant women to evaluate for a drug-associated risk of major birth defects, miscarriage or adverse maternal or fetal outcomes.”
US prescribing information · c042bf06-79a3-4dc7-ae05-3ef3cfae9d44 · read 2026-08-30
On people who are breastfeeding, the label states: “Risk Summary There are no data on the presence of oxybutynin in human milk, the effects on the breastfed infant, or the effects of oxybutynin chloride on milk production.”
US prescribing information · c042bf06-79a3-4dc7-ae05-3ef3cfae9d44 · read 2026-08-30
On people with reduced liver function, the label states: “There were no studies conducted with oxybutynin chloride extended-release tablets in patients with hepatic impairment.”
US prescribing information · c042bf06-79a3-4dc7-ae05-3ef3cfae9d44 · read 2026-08-30
On people with reduced kidney function, the label states: “There were no studies conducted with oxybutynin chloride extended-release tablets in patients with renal impairment.”
US prescribing information · c042bf06-79a3-4dc7-ae05-3ef3cfae9d44 · read 2026-08-30
Where the result stopped carrying
The head-to-head against behavioural training, which oxybutynin lost on both the diary endpoint and on how many patients wanted to stop
The immediate-release formulation's tolerability, which drove fifty years of reformulation rather than replacement
Correct use of the over-the-counter patch, misapplied by half the consumers studied before mitigation
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 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 (11)
It was studied for a different goal
The studies measured something else entirely. Nothing in this record points to this reason.
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 immediate-release tablet and syrup, oral extended-release tablet, transdermal system, and topical gel
✎ 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
Four routes for one molecule, and the reason for all of them is the same: avoiding or reducing first-pass conversion to N-desethyloxybutynin. The extended-release tablet slows absorption; the transdermal system and topical gel bypass the gut and liver entirely. None of them changes the drug. The extended-release tablet is swallowed whole and its non-absorbable shell may be visible in the stool, which is expected rather than a treatment failure.
✎ 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.
The recorded stepping schedule
What follows is the schedule printed on the label, recorded as it is written there. It is a record of what was done, not a recommendation.
US prescribing information · 02ff3be7-fc5c-4b91-8c67-ecdf6e19c42a · read 2026-08-28
Adults, starting dose: 5 or 10 mg once daily at approximately the same time each day
US prescribing information · 02ff3be7-fc5c-4b91-8c67-ecdf6e19c42a · read 2026-08-28
Adults, adjustment at approximately weekly intervals: Adjusted in 5-mg increments, up to a maximum of 30 mg/day — To achieve a balance of efficacy and tolerability, as recorded in the label
US prescribing information · 02ff3be7-fc5c-4b91-8c67-ecdf6e19c42a · read 2026-08-28
What it would be like to take◇Read from sources, not yet reviewed
What can go wrong
Sorted by where each line came from. A regulator's label and a report somebody sent in are not the same kind of fact.
·Worth asking a clinician aboutWritten into the record from the studies named on this page
Anticholinergic effects dominate and are dose- and formulation-dependent: dry mouth, constipation, blurred vision, somnolence and dizziness. Because the molecule is lipophilic and enters the central nervous system, confusion and cognitive impairment are described particularly in older adults, and this is the antimuscarinic most often named in anticholinergic-burden guidance. Heat-related risk is real, because sweating is a cholinergic function. Urinary retention, decreased gastrointestinal motility and caution in narrow-angle glaucoma appear as they do across the class.
Nobody counted how many people took this and were fine, so this cannot be turned into a rate.
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 immediate-release tablet and syrup, oral extended-release tablet, transdermal system, and topical gel
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The form used in the studies cited on this page.
No source is stored against this line.
What is sold
The extended-release tablet slows absorption; the transdermal system and topical gel bypass the gut and liver entirely. None of them changes the drug. The extended-release tablet is swallowed whole and its non-absorbable shell may be visible in the stool, which is expected rather than a treatment failure.
✎ 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
4 products list this as an active ingredient in the United States drug directory. 4 of them contain it and nothing else.
FDA National Drug Code directory · 17381-015 · read 2026-08-29
They are sold as patch and powder, taken transdermal.
FDA National Drug Code directory · 17381-015 · read 2026-08-29
The regulator's established pharmacologic class for it is cholinergic muscarinic antagonist [epc] and cholinergic muscarinic antagonists [moa].
FDA National Drug Code directory · 17381-015 · read 2026-08-29
7 published labels name it as an active ingredient. 7 of them describe this substance alone, which is where its own label text on this page comes from.
US prescribing information · c042bf06-79a3-4dc7-ae05-3ef3cfae9d44 · read 2026-08-29
Those labels are classed as human otc drug and human prescription drug.
US prescribing information · c042bf06-79a3-4dc7-ae05-3ef3cfae9d44 · read 2026-08-29
Oxybutynin Chloride Extended Release is extended-release tablets at Extended release tablets 5 mg, 10 mg and 15 mg, recorded as prescription product; fda label in effect 2023-05-31 in the United States.
US prescribing information · 02ff3be7-fc5c-4b91-8c67-ecdf6e19c42a · read 2026-08-28
Recorded price in US: 0.03232 USD per one millilitre, across 2 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
Recorded price in US: 0.04729–2.10406 USD per one unit as the pricing file counts it — a tablet, capsule, patch or single item, across 38 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 Oxybutynin 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 the immediate-release tablet has the placebo-controlled effect size quoted on the extended-release label — the placebo comparison was run on the newer formulation
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 oxybutynin specifically causes dementia — the cohort evidence is for cumulative anticholinergic exposure across all classes, and this molecule is singled out on lipophilicity rather than on a drug-specific trial
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That a 3.0-episode-a-day reduction on topical gel is a drug effect — 2.5 of it occurred on placebo gel
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 over-the-counter availability implies the drug is used as labelled — the study run to answer that question found otherwise
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 Oxybutynin 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.
Immediate release dries the mouth in 72.4% of patients; extended release in 34.9%
In plain words
The cheapest and most-prescribed form of this drug gives roughly seven patients in ten a dry mouth. The once-daily version halves that. Same molecule, same dose range — only the release rate differs.
What was measured
Incidence of dry mouth, constipation, somnolence, dizziness and blurred vision, extended release versus immediate release
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The US label for the extended-release tablet reports pooled adverse events against an immediate-release comparator arm. Dry mouth: 34.9% on extended release (n=774) against 72.4% on immediate release (n=199). Constipation 8.7% against 15.1%. Somnolence 5.6% against 14.1%. Dizziness 5.0% against 16.6%. Blurred vision 4.3% against 9.6%. Every one of those is roughly halved or better. The mechanism is first-pass metabolism: swallowing a rapidly dissolving tablet delivers a bolus to the liver, which converts a large fraction into N-desethyloxybutynin, an active antimuscarinic that the label states has similar in vitro activity to the parent. Slowing the release moves absorption further down the gut and changes the parent-to-metabolite ratio. The clinical consequence of a pharmacokinetic decision is a 37-percentage-point difference in whether a patient can taste their food.
Source
US prescribing information for oxybutynin chloride extended-release tablets, Adverse Reactions and Clinical Pharmacology sections (openFDA drug label endpoint)
Role in the trial
Not matched to a registered study
Identity check
no open identity hold
Audit mark
verified
Review state
Written into the record, not signed off as a reviewed claim
Behavioural training beat this drug, and the drug group wanted out
In plain words
The only randomised trial to compare a bladder drug against structured behavioural training used oxybutynin, and the training won. Three quarters of the people on the drug wanted to switch to something else. One in seven of the training group did.
What was measured
Percentage reduction in incontinence episodes and proportion wanting to change treatment, by randomised arm
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
Burgio and colleagues randomised 197 community-dwelling women aged 55 and over with persistent urge incontinence to behavioural training, oxybutynin, or placebo. Behavioural training reduced incontinence episodes by a mean of 80.7%, significantly more than the drug at 68.5% (P=.04), and both beat placebo at 39.4% (P<.001 and P=.009). Patient-perceived improvement of "much better" was reported by 74.1% of the behavioural group against 50.9% on the drug and 26.9% on placebo. The most telling number is the last: 14.0% of the behavioural group wanted to change to another treatment, against 75.5% in each of the other two groups. Note what that means — three quarters of the drug group and three quarters of the placebo group wanted out, at the same rate, despite a real difference in diary outcomes between them.
Written into the record, not signed off as a reviewed claim
Against placebo the extended-release tablet is worth about one episode a day
In plain words
In the trial that registered the once-daily tablet, patients on the drug had 15.8 fewer weekly leaks and patients on placebo had 7.6 fewer. That is a real difference of about eight leaks a week, or a bit over one a day.
What was measured
Change in weekly urge urinary incontinence episodes against placebo
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The Clinical Studies section of the extended-release label reports urge urinary incontinence episodes falling 15.8 per week on the drug against 7.6 per week on placebo. Converted to the units the rest of this class reports in, that is 2.26 against 1.09 episodes per 24 hours — a treatment effect of about 1.17 episodes a day, at the upper end of what any drug in this indication has shown. Two things qualify it. The placebo arm still accounts for nearly half the total movement. And no comparable modern placebo-controlled trial exists for the immediate-release tablet, which is the form most prescriptions in this class are actually written for, because it was approved in 1975 and never had to produce one.
Source
US prescribing information for oxybutynin chloride extended-release tablets, Clinical Studies section (openFDA drug label endpoint)
Role in the trial
Not matched to a registered study
Identity check
no open identity hold
Audit mark
verified
Review state
Written into the record, not signed off as a reviewed claim
The topical gel beat placebo by half an episode a day, and placebo took away 2.5
In plain words
A 789-patient trial of oxybutynin skin gel found the drug removed 3.0 leaks a day and the placebo gel removed 2.5. Almost all the improvement people felt came from something other than the drug.
What was measured
Change from baseline to week 12 in average daily incontinence episodes, gel versus placebo gel
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Study OG05009 (NCT00350636), sponsored by Watson Pharmaceuticals, randomised 789 patients to oxybutynin topical gel (n=389) or placebo gel (n=400) for 12 weeks, with change in average daily incontinence episodes as the primary endpoint. The reported result was -3.0 (SD 2.73) on drug against -2.5 (SD 3.06) on placebo. That is the largest placebo response of any trial on this page, and the smallest absolute margin. Large placebo responses are characteristic of applied-to-the-skin interventions in symptom-diary conditions, which is a reason to read the difference rather than the change, and a reason to distrust any presentation of this trial that quotes only the -3.0.
Written into the record, not signed off as a reviewed claim
The dementia association is dose-graded and this is the molecule most implicated
In plain words
A ten-year study of 3,434 older adults found that the more anticholinergic medicine someone had taken, the higher their chance of a later dementia diagnosis. Oxybutynin is the most brain-penetrating drug in this class.
What was measured
That oxybutynin specifically causes dementia — the cohort data are for cumulative anticholinergic exposure across all classes, and the singling out of this molecule rests on its lipophilicity rather than on a drug-specific randomised result
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Gray and colleagues followed 3,434 people aged 65 and over with no dementia at entry for a mean 7.3 years, using computerised dispensing records to compute total standardised daily doses over the preceding ten years and excluding the most recent twelve months to reduce reverse causation. Dementia developed in 797 (23.2%). Adjusted hazard ratios against nonuse were 0.92 (95% CI 0.74 to 1.16) at 1 to 90 TSDDs, 1.19 (0.94 to 1.51) at 91 to 365, 1.23 (0.94 to 1.62) at 366 to 1,095, and 1.54 (1.21 to 1.96) above 1,095, with a significant trend (P<.001). Bladder antimuscarinics were among the three most-used classes. Coupland and colleagues later reported an adjusted odds ratio of 1.65 (1.56 to 1.75) for bladder antimuscarinics specifically. Oxybutynin is tertiary, lipophilic and the most readily brain-penetrating of the class, so the pharmacology points the same way as the epidemiology — but no randomised trial in this indication has ever been powered for a cognitive endpoint, and none is likely to be.
Written into the record, not signed off as a reviewed claim
The over-the-counter study found half the users applied the patch wrongly
In plain words
Before the transdermal form was sold without a prescription, a study watched 855 real consumers use it. Over half used it incorrectly, and one in seven kept using it after developing a symptom the label told them to stop for.
What was measured
Percentage misusing the transdermal system and percentage continuing use despite labelled warning symptoms
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
The Oxytrol Transdermal System Actual Use Study (NCT04534491, sponsored by Bayer) enrolled 855 participants in a single-group, unmasked design. The registered primary outcome was the percentage who did not stop use when they developed a new symptom named in the labelling or when their condition worsened, including abdominal or pelvic pain: 14.4% (95% CI 12.0 to 17.2) of 727 participants pre-mitigation, falling to 3.4% (2.2 to 5.0) after mitigating factors such as physician contact were accounted for. Patch misuse — wrong duration or simultaneous application of more than one — was 51.7% pre-mitigation and 21.2% post-mitigation. Among 324 participants who continued despite concerning symptoms, 16 were assessed as facing medical risk and 24 possible risk. The switch went ahead. The finding that half the participants misused the product is a real, measured, published result about how this drug is used outside a clinic, and it exists because a regulator required it.
Source
ClinicalTrials.gov results record, Oxytrol Actual Use Study, NCT04534491
Role in the trial
Not matched to a registered study
Identity check
no open identity hold
Audit mark
caution
Review state
Written into the record, not signed off as a reviewed claim
A 1975 drug whose efficacy evidence was assembled in the 2000s for a newer tablet
In plain words
Oxybutynin was approved half a century ago, under a standard of evidence that no longer exists. The placebo-controlled numbers on its label today come from studies run decades later to register the once-daily version.
What was measured
Provenance of the placebo-controlled efficacy figures carried on the current US label
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The immediate-release tablet reached the US market in 1975. Overactive bladder as a defined syndrome, the standardised three-day bladder diary, and the regulatory expectation of a placebo-controlled trial with a diary primary endpoint all postdate it. The efficacy data now quoted for oxybutynin — the 15.8 against 7.6 weekly urge incontinence episodes — come from the extended-release registration programme, and the comparisons that establish the immediate-release form's effect are non-inferiority comparisons against that newer product rather than against placebo. The direction of inference is backwards from the usual one: the old drug's efficacy is supported by the new formulation's trials, and the new formulation's advantage is supported by a tolerability comparison against the old drug.
Source
US prescribing information for oxybutynin chloride extended-release tablets, Clinical Studies and Adverse Reactions sections; approval year as held on this record
Role in the trial
Not matched to a registered study
Identity check
no open identity hold
Audit mark
caution
Review state
Written into the record, not signed off as a reviewed claim
How many documents were read
6 documents were read for this substance.
RNAWiki source record
5 of them state the same volumeOfDistribution, and they agree.
RNAWiki source record
Where else this substance is registered
FDA substance identifier (UNII)
L9F3D9RENQ
CAS registry number
5633-20-5
PubChem compound
4634
RxNorm concept
32675
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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
4 approved applications cover products containing this substance. The earliest was NDA021351, approved 20030226 to ALLERGAN.
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What is not here
7 questions this page could not answer
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The older medicine-wide conclusion held in this record
Written for a clinical reader, and about the medicine as a whole rather than about one indication, population and set of trials. RNAWiki does not treat it as a programme conclusion and no reviewer has signed it off in that form. It is here word for word because it is what the record holds.
A non-selective muscarinic antagonist from 1975 whose extended-release tablet removed 15.8 urge incontinence episodes a week against 7.6 on placebo, and whose entire subsequent development history — extended release, transdermal patch, topical gel — exists to keep its own active metabolite out of the salivary gland, where the immediate-release form produces dry mouth in 72.4% of patients against 34.9% for the extended-release version.
Recorded evidence blocks (9)
Q1
On the Oxybutynin label: indicated for what?
"Oxybutynin chloride is a muscarinic antagonist indicated for the treatment of overactive bladder with symptoms of urge urinary incontinence, urgency, and frequency. ( 1 ) Oxybutynin chloride extended-release tablets are also indicated for the treatment of pediatric patients aged 6 years and older with symptoms of…": indications and usage on Oxybutynin's label. DailyMed label · ec4fd95f-16dc-4acf-b560-b67b7aaef08b · 2024-09-13
Q2
68 registered trials of Oxybutynin — at which phases?
Registered studies posting no result
50 of 68
68 registered studies of Oxybutynin: 19 phase3, 13 na, 12 phase4, 11 phase2, 8 phase1, 5 na or unstated, 1 early phase1. CLINICALTRIALS_SNAPSHOT · 2026-09-01
300 with a PubMed record
Show the evidence
phase3
19
na
13
phase4
12
phase2
11
phase1
8
na or unstated
5
8 more recorded rows
early phase1
1
completed
50
unknown
7
recruiting
6
withdrawn
2
active not recruiting
1
not yet recruiting
1
terminated
1
recorded 2026-09-01 · last checked 2026-09-04
Q3
2 of Oxybutynin's trials stopped: accrual/recruitment, other?
NCT00304499, NCT00649129, NCT00649727, NCT00649259, NCT00293839 and NCT00648843, and 25 more
Completion dates
oldest 1996-12; newest 2020-05-01
Show the evidence
Trial
NCT00304499
1996-12
NCT00649129
2002-08
NCT00649727
2002-08
NCT00649259
2002-11
NCT00293839
2002-12
NCT00648843
2003-01
14 further recorded trials
NCT00650481
2003-01
NCT00990886
2005-01
NCT00170768
2005-05
NCT00338624
2005-06
NCT00816972
2005-06
NCT00649272
2006-02
NCT00749632
2008-10
NCT01118429
2009-06
NCT00926926
2009-07
NCT01477736
2010-11
NCT00629642
2011-01-28
NCT01310712
2011-03
NCT01716624
2012-04
NCT01899794
2013-04
Q6
At the median, Oxybutynin's trials enrolled 67 people — anything larger?
Median enrolment
67
Largest enrolment
5589
Registered trials counted
68
Q7
What do 670 spontaneous reports say about Oxybutynin — 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.
Oxybutynin appears in spontaneous reports to regulators. Across the 10 most-reported reaction terms, 670 reaction mentions were counted: confusional state 104; drug hypersensitivity 103; dry mouth 101; constipation 78. FAERS via Open Targets · CHEMBL1133 · 2026-06-24
Show the evidence
confusional state
104
drug hypersensitivity
103
dry mouth
101
constipation
78
fall
70
urinary retention
58
4 more recorded rows
somnolence
47
vision blurred
38
hyponatraemia
36
cognitive disorder
35
recorded 2026-06-24 · last checked 2026-09-04
Q8
Which 10 reactions does Oxybutynin's label not list?
( 7 ) Co-administration with strong cytochrome P450 (CYP) 3A4 inhibitors (e.g., ketoconazole) increases the systemic exposure of oxybutynin.
drug_interactions
Mean oxybutynin plasma concentrations were approximately 2 fold higher when oxybutynin chloride extended-release tablets were administered with ketoconazole, a potent CYP3A4 inhibitor.
drug_interactions
Other inhibitors of the cytochrome P450 3A4 enzyme system, such as antimycotic agents (e.g., itraconazole and miconazole) or macrolide antibiotics (e.g., erythromycin and clarithromycin), may alter oxybutynin mean pharmacokinetic parameters (i.e., Cmax and AUC).
pharmacokinetics
Metabolism Oxybutynin is metabolized primarily by the cytochrome P450 enzyme systems, particularly CYP3A4 found mostly in the liver and gut wall.
clinical_pharmacology
Metabolism Oxybutynin is metabolized primarily by the cytochrome P450 enzyme systems, particularly CYP3A4 found mostly in the liver and gut wall.
ChEMBL 37 — CC BY-SA 3.0 Unported · ClinicalTrials.gov — US Government work · Open Targets 26.06 — CC0 · mixed register set; per-register licences in docs/specs/corpus-20k-sources.md · openFDA / DailyMed — US Government work
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