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S-23

  • Research compound
  • Still being tested
  • Identity checked
  • Sources last checked 2026-09-04

This page shows what was measured, who it was measured in, and what that does not settle.

What S-23 does in the body

Male contraception in rats — never tested in humans for anything

S-23 binds the androgen receptor very tightly and, unlike the SARMs designed to spare the prostate, it behaves as a full agonist. In rats that produced two effects at once. In muscle and bone it acted like a strong androgen: lean mass up, bone density up, fat down, all dose-dependently. In the brain it acted like a strong androgen too, which meant the pituitary stopped sending the signals that drive the testis, and sperm production stopped. In four of six animals at the contraceptive dose there was no sperm in the testis at all, and there were no pregnancies. Both halves are the same drug at the same receptor.

What happened in people

Dose-dependent increases in lean mass and bone mineral density with reduced fat mass, in the same animals

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.

The limit that matters most

That it is "the strongest SARM", a claim resting on rodent potency assays that were designed to select a contraceptive, not a performance compound

Where it acts
Androgen receptor in levator ani muscle, prostate, bone, and the hypothalamic-pituitary axis
Kind of result
A number that stands in for health
Supervision
Professional supervision is normally required. It is a prescription or clinician-administered medicine where it is approved.

What the registries record it as

  • The substance registry classes this as chemical.

    FDA substance registry · XDK89456WM · read 2026-08-29

  • The supplement label database classes it as botanical, under the name S-23.

    NIH Dietary Supplement Label Database · 9797 · read 2026-08-29

  • Its recorded molecular formula is C18H13ClF4N2O3, weighing 416.8.

    PubChem record · 24892822 · read 2026-08-29

Where each sentence above came from

No recorded sentence describes the change this makes in a way that stands on its own. The page opens with what it is taken for instead, and the recorded explanation follows below.

Shown as the opening line on this page.

A limit recorded against this substance. Not signed off as a reviewed claim.

The four opening statements run to 138 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.

Placebo

A placebo is a dummy treatment given so the real one can be compared with it.

A picture of it, and where the picture fails

A placebo is like a blank control in an experiment.

Where that stops being true. A blank does nothing. People given a placebo often do get better.

What people get wrong. A placebo effect is read as imaginary. The improvement is measured and real.

An inactive intervention matched in appearance to the test intervention, used to control for non-specific effects.

Comparator

A comparator is whatever the treatment was measured against.

A picture of it, and where the picture fails

It is like the other runner in a race.

Where that stops being true. A race has one winner. A study can show both arms improved.

What people get wrong. Results are read without asking what the other group got. Beating nothing is not beating a treatment.

The control condition against which the experimental intervention is assessed.

What happened in peopleRead 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.

Spermatogenesis and fertility in mating trials, with lean mass, fat mass and bone mineral density as secondary measures

The study showed what it set out to show

Who was studied
Jones 2009 rat characterisation for hormonal male contraception
How many people
0
Study design
Preclinical, male rats, up to 10 weeks
Compared against
Not recorded for this study
Kind of result
Measured performance
What was found
Four of six animals with no testicular sperm and zero of six pregnancies at S-23 0.1 mg/day with oestradiol benzoate; full reversal with 100% pregnancy rate after 100 days
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. 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 capsule or liquid; no established human dose

Interval reported. Not recorded in this summary

Written into the record, not signed off as a reviewed claim.

Urinary detection window and metabolite profile after a single approximately 8 mg oral dose

The study showed what it set out to show

Who was studied
Ameline 2022 single-dose human administration, analytical purpose
How many people
1
Study design
Analytical excretion study, one volunteer
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Parent detectable 2 hours to 28 days at 0.5 to 93 ng/mL; hydroxy-S-23 detectable to 28 days; hair negative at one month with LOQ 0.1 pg/mg
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. 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 capsule or liquid; no established human dose

Interval reported. Not recorded in this summary

Written into the record, not signed off as a reviewed claim.

What we know
RNAWiki holds 2 written-up human studies for this substance, each with the question it asked.
How we know it
Each card names the study, the number of people and what the study set out to measure.
What this does not prove
These summaries were written by a person and have not been signed off as reviewed claims.
Why it matters
A study that failed is as informative as one that worked, and both are here.
What we still do not know
No reviewed claim exists, so no exact population, effect size or interval is published yet.

What it changes in the bodyRead 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.

  1. Start

    S-23

    What a person takes: Oral capsule or liquid; no established human dose.

    The measurement behind this step

    Sold as a capsule or dropper-bottle liquid. The only documented human dose is a single 8 mg tablet taken for an analytical excretion study. The rat doses that produced both the anabolic and the contraceptive effects were 0.1 mg/day and above, in animals of about 300 grams, and cannot be scaled to a person by any simple arithmetic.

  2. Getting in

    Oral, with a long tail

    Taken by mouth. One 8 mg dose was still measurable in urine four weeks later.

    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

    Aryl propionamide with oral bioavailability described as favourable in the rat characterisation. In the single documented human administration, parent compound was measurable in hydrolysed urine from 2 hours to 28 days at 0.5 to 93 ng/mL.

  3. Reaching the cell

    Enters the cell and binds tightly

    It crosses the cell membrane and locks onto the androgen receptor at very low concentrations.

    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
  4. What it acts on

    Switches the receptor fully on

    Unlike the SARMs designed to be gentle on the prostate, it turns the receptor all the way on, with only a modest preference for muscle.

    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

    Full agonism at AR, with an ED50 of 0.079 mg/day in levator ani muscle against 0.43 mg/day in prostate in castrated rats — roughly fivefold selectivity, narrow by the standards of the compounds developed for prostate sparing.

  5. The change it makes

    Muscle and bone build; the pituitary shuts down

    Lean mass and bone density rise. At the same time the brain reads the signal as an excess of androgen and stops driving the testis.

    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

    Dose-dependent increases in lean mass and bone mineral density with reduced fat mass. Concurrently, LH suppressed by more than 50% at doses above 0.1 mg/day over 14 days, with FSH suppression over the longer regimen — the negative feedback that abolished spermatogenesis.

  6. What that does for a person

    Azoospermia, and full reversal after 100 days

    Four of six rats had no sperm in the testis and none of six mating trials produced a pregnancy. All of it reversed after a hundred days off the drug.

    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

    Four of six animals in the oestradiol plus S-23 0.1 mg/day group showed no testicular sperm, with zero pregnancies in six mating trials. Full reversibility with a 100% pregnancy rate after 100 days of recovery. No human equivalent has been measured.

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 unclearRead 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.

  • Rats, in the published work. Outside that, men buying it online as the most potent available SARM, and at least one volunteer who took a single 8 mg tablet for an analytical study.

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.

Where the result stopped carrying

  • No pharmaceutical sponsor advanced it and no human trial has ever been registered, seventeen years after its characterisation
  • Its tissue selectivity window is roughly fivefold, far narrower than the class was designed to achieve
  • 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 takeRead 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 takeRead 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

Still being tested

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 capsule or liquid; no established human dose

Source-linked record

Where this came from

A person wrote this into the record with the study named beside it. No reviewer has signed it off.

The form and route recorded on this substance.

No source is stored against this line.

Who oversees it

Professional supervision is normally required. It is a prescription or clinician-administered medicine where it is approved.

Quoted from a source

Where this came from

Copied from a source RNAWiki stored, with the source named.

The identity record classes it as investigational; no register records an approval.

No source is stored against this line.

What is in the pack

Sold as a capsule or dropper-bottle liquid. The only documented human dose is a single 8 mg tablet taken for an analytical excretion study. 1 mg/day and above, in animals of about 300 grams, and cannot be scaled to a person by any simple arithmetic.

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 takeRead 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

No human safety data exist. In rats, the documented effects at contraceptive doses are suppression of LH and FSH, abolition of spermatogenesis in most animals, and prostate shrinkage, alongside increases in lean mass and bone density. All of it reversed within 100 days of stopping in that species. The androgen class effects — suppression of endogenous testosterone, reduced HDL cholesterol, and the drug-induced liver injury reported across this class — apply by mechanism and have not been measured for this compound in humans.

Nobody counted how many people took this and were fine, so this cannot be turned into a rate.

Where this came from

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 unclearNothing found in the sources checked

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 capsule or liquid; no established human dose

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 only documented human dose is a single 8 mg tablet taken for an analytical excretion study. 1 mg/day and above, in animals of about 300 grams, and cannot be scaled to a person by any simple arithmetic.

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.

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 takeRead from sources, not yet reviewed

What you could measure

This one is decided with a clinician, so this section holds questions to ask rather than a plan to run.

Self-experiment planning is not offered for a prescription or clinician-supervised medicine, investigational agent. The questions below are for a clinician or pharmacist.

Questions worth asking

  • Which of the trials of S-23 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 unclearRead 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 rat body composition result predicts a human muscle effect — no human has been studied for any clinical endpoint

Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.

The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.

What would change this

A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.

RNAWiki has not yet published a reviewed conclusion for this use.

Goes past the evidence

That the rat contraceptive result does not apply to men, when the mechanism producing it is the same negative feedback that operates in every mammal

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 it is "the strongest SARM", a claim resting on rodent potency assays that were designed to select a contraceptive, not a performance compound

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 unclearRead from sources, not yet reviewed

What nobody knows yet

Open questions, each with why it is open and what would close it.

How much did people take in the studies?

The sources RNAWiki checked hold nothing for this field.

Why it matters. A result belongs to an amount. Without the amount the result floats free.

What would answer it

A stored source that records 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.

How fast does the body clear it?

The sources RNAWiki checked hold nothing for this field.

Why it matters. Without this, nothing on this page can say how long anything lasts.

What would answer it

A stored source that records 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 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 S-23 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 peopleRead 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.

Binding constant 1.7 nM, and a full agonist rather than a partial one
In plain words
S-23 binds the androgen receptor about as tightly as anything in this class, and switches it fully on rather than partly on.
What was measured
Androgen receptor Ki; ED50 in levator ani muscle and in prostate
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Jones et al. characterised S-23 with an inhibitory constant of 1.7 plus or minus 0.2 nM and identified it as a full agonist in vitro. In castrated male rats the ED50 was 0.079 mg/day for levator ani muscle and 0.43 mg/day for prostate, a separation of roughly fivefold in favour of muscle. That tissue selectivity is real and it is much narrower than the separation the prostate-sparing SARMs were designed for. A full agonist with a fivefold window is closer in behaviour to an anabolic steroid than to enobosarm, and its endocrine effects in the same paper bear that out.
Source
Jones A et al., Endocrinology 2009;150:385-395
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
Four of six rats had no sperm in the testis, and no pregnancies resulted
In plain words
At the contraceptive dose, combined with oestradiol, four of six male rats had no sperm at all and none of six mating trials produced a pregnancy. Fertility returned completely after 100 days off the drug.
What was measured
Testicular sperm presence and pregnancy rate in mating trials; LH and FSH suppression
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
In intact male rats treated for 14 days, S-23 alone suppressed LH by more than 50% at doses above 0.1 mg/day, with prostate shrinkage and levator ani growth at the same time. In intact rats treated for up to 10 weeks with S-23 plus oestradiol benzoate — the oestradiol being required to maintain sexual behaviour in rats — S-23 suppressed both LH and FSH and produced biphasic effects on androgenic tissue and spermatogenesis. In the oestradiol plus S-23 0.1 mg/day group, four of six animals showed no sperm in the testis and zero of six mating trials produced a pregnancy. Oestradiol alone had no effect on spermatogenesis. After treatment stopped, infertility was fully reversible, with a 100% pregnancy rate after 100 days of recovery.
Source
Jones A et al., Endocrinology 2009;150:385-395
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 anabolic finding and the contraceptive finding are the same experiment
In plain words
The same study that abolished sperm production also reported dose-dependent increases in bone density and lean mass and a fall in fat mass. Both results come from the same animals.
What was measured
Bone mineral density, lean mass and fat mass by dose in the same animals
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Jones et al. report that S-23 increased bone mineral density and lean mass and reduced fat mass in a dose-dependent manner, in the same rat programme that established its contraceptive effect. This matters because the two findings are routinely separated in the way the compound is described: the body composition result is quoted in supplement listings and the azoospermia result is not, although they are two paragraphs of one paper describing one set of animals given one drug. There is no dose in that paper at which the anabolic effect appeared and the gonadotropin suppression did not.
Source
Jones A et al., Endocrinology 2009;150:385-395
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
Rat contraception does not transfer to humans, in either direction
In plain words
The rat work cannot tell you that S-23 will make a man infertile, and it cannot tell you that it will not. Nobody has looked.
What was measured
That the rat contraceptive result either does or does not apply to men — neither direction has been tested, and the underlying mechanism is species-general
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The rat regimen required oestradiol benzoate to maintain sexual behaviour, a species-specific requirement that has no human equivalent, and rat spermatogenesis differs from human spermatogenesis in duration and in gonadotropin dependence. Extrapolating the azoospermia finding to men is therefore not valid — and neither is dismissing it, because the mechanism through which it happened, suppression of LH and FSH by androgen receptor agonism at the hypothalamus and pituitary, is the same mechanism that operates in men and is well documented for every androgen. The honest position is that S-23 has never been assessed for effects on human spermatogenesis at any dose.
Source
Jones A et al., Endocrinology 2009;150:385-395
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
One 8 mg tablet stayed detectable in urine for 28 days
In plain words
A volunteer took a single 8 mg dose. It was detectable in urine from two hours afterwards until 28 days later. A hair sample taken a month afterwards was negative.
What was measured
Urinary detection window and concentration range after a single 8 mg oral dose
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Ameline et al. generated four S-23 metabolites with human liver microsomes — hydroxy-S-23, O-dephenylate-S-23, S-23-glucuronide and hydroxy-S-23-glucuronide — and then studied urine after a single oral administration of approximately 8 mg to a volunteer. Parent S-23 was detectable in hydrolysed urine from 2 hours to 28 days post administration, at concentrations between 0.5 and 93 ng/mL. Only one of the four in vitro metabolites, hydroxy-S-23, was found in urine, also up to 28 days, and it did not extend the detection window because its ratio to parent was always below 1. A dihydroxy metabolite not predicted in vitro was found in vivo. A hair sample taken one month after a single tablet was negative for both, with a limit of quantification of 0.1 pg/mg. This is the only published human administration of S-23 and its purpose was analytical, not clinical.
Source
Ameline A et al., J Pharm Biomed Anal 2022;212:114660
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
A contraceptive candidate rebranded as the strongest SARM
In plain words
Every published fact about S-23 comes from a programme whose goal was to stop sperm production. It is now sold as a performance compound, with that goal unmentioned.
What was measured
That potency in a rat anabolic assay is the relevant fact about this compound, when the same potency is what suppressed spermatogenesis in the same animals
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The paper that established S-23 states its purpose in the title: a selective androgen receptor modulator for hormonal male contraception. Its potency, its full-agonist behaviour and its steep gonadotropin suppression are the properties that made it a contraceptive candidate, and they are the same properties now cited as making it the strongest SARM available. No pharmaceutical sponsor took it further, no human trial was registered, and the compound entered the doping market recently enough that its analytical characterisation postdates its consumer availability. The reframing is not a scientific development; it is the same molecule described by people with a different purpose.
Source
Jones A et al., Endocrinology 2009;150:385-395; Ameline A et al., J Pharm Biomed Anal 2022;212:114660
Role in the trial
Not matched to a registered study
Identity check
no open identity hold
Audit mark
contested
Review state
Written into the record, not signed off as a reviewed claim

Where else this substance is registered

FDA substance identifier (UNII)
XDK89456WM
CAS registry number
1010396-29-8
PubChem compound
24892822
DrugBank
DB07419

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

  • Passed

    Safety mode resolved

    The identity record classes it as investigational; no register records an approval.

  • Passed

    Canonical metadata present

    slug and display name present

What is missing or unclearRead from sources, not yet reviewed

What to learn next

Ordered by what would most change how you read this page, starting with what is easiest to misunderstand.

This order is fixed in code and does not count clicks or time on the page.

What is not here

8 questions this page could not answer

These sections were prepared and left out because there was nothing to put in them. They are listed rather than hidden, so the gaps in this record are visible.

  • What was measured, goal by goal — found nothing in the sources checked.
  • How close this is to real life — found nothing in the sources checked.
  • Felt, measured, or meaningful — found nothing in the sources checked.
  • How long anything takes — found nothing in the sources checked.
  • What it may clash with — found nothing in the sources checked.
  • Other ways to the same goal — found nothing in the sources checked.
  • How this medicine reached us — found nothing in the sources checked.
  • What changed on this page — found nothing in the sources checked.

The record as stored

The full record, for auditing

Everything above is built from what is below. This layer keeps the technical vocabulary, record identifiers and every stored row, so a reader who wants to check the page can.

The older medicine-wide conclusion held in this record

Written for a clinical reader, and about the medicine as a whole rather than about one indication, population and set of trials. RNAWiki does not treat it as a programme conclusion and no reviewer has signed it off in that form. It is here word for word because it is what the record holds.

A rat male-contraceptive candidate with an androgen receptor binding constant of 1.7 nM, in which four of six treated animals had no sperm in the testis, sold as a muscle-building compound to men on the strength of the same paper's lean-mass finding.

Recorded evidence blocks (0)
Where it is registered
Identifiers, relations and other names

The exact record

ChEMBL id
CHEMBL512283
PubChem CID
24892822
CAS number
1010396-29-8
InChIKey
SSFVOEAXHZGTRJ-KRWDZBQOSA-N
Also called
CHEMBL512283
Trade name
No trade name; sold under its laboratory code
Sources (1)

Sources

Europe PMC — metadata only, under the recorded legal gate

How these records are assembled · Which registers were checked

Index-quality checks
  • identity passed: no open identity hold
  • required summary fields resolved: 4 required field(s) not terminal: Why people use it, Best-supported result, Biggest unanswered question, Human evidence
  • public claims reviewed: 0 reviewed claim(s); drafts are never rendered
  • source coverage passed: 1 source rows
  • no critical contamination: no quarantine open
  • canonical metadata passed: slug and display name present
  • no raw internal fields: enforced by the copy-contract test over the rendered page

This is a record of evidence. It is not medical advice, and it does not say this substance suits you. Nothing here says any substance on RNAWiki is appropriate for a child.