What is YK11?
YK11 is a special case among the SARM-like compounds. Structurally it is a steroid derivative but it behaves like a selective androgen receptor modulator. It has additionally been described in cell models as a myostatin inhibitor, a compound that could loosen the muscle's natural growth brake.
Up front: there are essentially no human data on YK11. Everything available comes from cell culture.
Comparison
YK11 and other SARMs
All bind the androgen receptor, as described in the TPD lexicon. Tap a card to open its entry.
Simplified: YK11 is the only compound here with a steroid backbone. The route via follistatin is known only from cell culture, there is no comparison in humans. 21
How it works
YK11 activates the androgen receptor as a partial agonist. In muscle cells it increased the production of follistatin, an endogenous counterpart to myostatin. Since myostatin brakes muscle growth, more follistatin would theoretically be a lever for more growth.
Important: this is described in C2C12 muscle cells, not in humans. Whether and how strongly it transfers is open.
Where it acts
Where YK11 acted in cell and animal studies
Tap a point or a card. Colour = androgen receptor, grey = observed. No data from humans.
- Muscle cells
More follistatin and muscle control factors than with DHT, cells matured faster (cell culture)1
AR - Bone
Bone cells grew and mineralised more, defects in rats healed better5
AR - Brain (hippocampus)
In rats more inflammatory messengers and oxidative stress, poorer memory8
Observed in trials - Blood (inflammation)
In mice with sepsis fewer inflammatory messengers and fewer deaths6
Observed in trials
Known targets2
Compound PubChem CID 119058028 (YK11): one described target, Partial agonist in cell studies, without N/C interaction.
- Gene
- AR
- UniProt
- P10275
- ChEMBL
- CHEMBL1871
- Action
- Partial agonist in cell studies, without N/C interaction
How to take it
Oral, often split across two doses.
- Because of the shorter duration of action, it is frequently split.
- With some water, with or without food.
- Cycles are kept short.
Dosing
Dosing
Dosing, titration and syringe
Loading the dosing information …
- Getting started and stepping up, drawn as a staircase
- Units on the U-100 syringe for every step
- How long one vial lasts
What the research shows
The central study (Kanno, 2013) showed that YK11 in C2C12 muscle cells stimulated the production of follistatin and through it promoted myogenic differentiation. The effect could be reversed with a follistatin antibody, which supports the mechanism.
This is a clean preclinical work but it is cell culture. There are no human studies, no human pharmacokinetics and no long-term data. YK11 is clearly experimental.
Research status
Where the research stands
YK11 has never been tested in a registered human trial. The data come from cell cultures and studies in mice and rats. As of 26 Oct 2026. 11
- Preclinical Cell studies since 2011, later mice and rats
- Phase 1 no registered trial
- Phase 2 no registered trial
- Phase 3 no registered trial
- Approval not yet
So far there is no registered trial in humans. 11
Side effects
- The case literature on SARM-like compounds documents liver strain. For YK11 the window is judged especially narrow.
- As an androgenically active compound, suppression of the body's own axis is to be expected.
- Solid human side-effect data simply do not exist.
Practice
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Keep expectations on the floor, everything rests on cell models.
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If at all, very low and short.
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Banned in official competition.
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Keep an eye on liver and blood values.
Storage
Store dry, cool and protected from light, out of reach of children. Keep the original container closed and mind the expiry date.
