S4 (Andarine) is a nonsteroidal selective androgen receptor modulator (SARM) developed by GTx Inc.
🔬 Studied for: Lean-Mass & Bone Research
💊 Also studied for: Visual-Disturbance Research
🧪 Not FDA-approved — sold strictly for laboratory research
📈 No standardized human dosage established in published literature
S4 (Andarine) is a nonsteroidal selective androgen receptor modulator (SARM) developed by GTx Inc. in the same research program that produced Ostarine, studied for anabolic activity in muscle and bone tissue.
S4 binds the androgen receptor and is studied for tissue-selective anabolic activity similar to other SARMs; it additionally shows affinity for the androgen receptor in ocular tissue, a distinguishing pharmacological property compared to other compounds in the class.
These are effects S4 (Andarine) has been studied for in available preclinical and early research — not claims about guaranteed outcomes.
Preclinical studies examined S4's effects on muscle and bone tissue as part of GTx's early SARM development program, alongside the related compound Ostarine, before development of S4 specifically was deprioritized.
S4's affinity for androgen receptors in ocular tissue is well documented in the research literature as the basis for reported visual side effects (such as difficulty adapting to darkness and yellow-tinted vision), a distinguishing safety consideration researchers cite when comparing S4 to other SARMs.
No FDA-approved or large-scale human clinical trial dosage exists for S4. Doses referenced in available preclinical and limited early research are documented in that literature and do not constitute an established human protocol.
Compound X does not provide dosing recommendations. S4 (Andarine) is sold for laboratory research use only and is not intended for human consumption.
The visual disturbances associated with S4 are its most consistently documented and distinguishing reported effect, attributed to androgen receptor activity in eye tissue; it has not completed human efficacy trials at the level of Ostarine or LGD-4033, has no FDA approval, and is banned by the World Anti-Doping Agency.
No. S4 (Andarine) is not FDA-approved for any indication and is sold strictly as a research chemical, not a medication or dietary supplement.
Lean-Mass & Bone Research — Preclinical studies examined S4's effects on muscle and bone tissue as part of GTx's early SARM development program, alongside the related compound Ostarine, before development of S4 specifically was deprioritized.
In the US, UK, Canada and Australia, S4 (Andarine) is generally sold labeled "for research use only, not for human consumption." It is not approved as a dietary supplement or medication in any of these countries.
S4/Andarine research is indexed on PubMed under search terms such as "S4 Andarine SARM" and "GTx androgen receptor modulator ocular."
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