S4 (Andarine) Capsules
60 hard gelatin capsules, 25 mg each, of an early nonsteroidal aryl-propionamide SARM studied in rats. A small molecule, not a peptide. Each lot is tested in the manufacturer’s own laboratory.
| Compound | Andarine (S-4), selective androgen receptor modulator |
|---|---|
| CAS number | 401900-40-1 |
| Molecular formula | C19H18F3N3O6 |
| Contents | Andarine: 25 mg per capsule |
| Form | Hard gelatin capsules containing the active substance blended with microcrystalline cellulose, packed in a sealed bottle |
| Storage, sealed | Store at room temperature (15–25 °C) in the tightly closed original container, dry and protected from light |
| Format | Capsules in a sealed bottle |
Sizes and lots
- 25 mg × 60 · 1 bottle — $63.99
- 25 mg × 60 · Kit of 10 — $568.87
S4, also called andarine, is one of the first nonsteroidal selective androgen receptor modulators (SARMs) shown to act selectively in animals, an aryl-propionamide described in 2003. It is a small molecule, not a peptide. This listing is a bottle of 60 hard gelatin capsules, each holding 25 mg of andarine blended with microcrystalline cellulose. Its literature is preclinical: receptor binding and reporter assays, castrated-rat studies of tissue selectivity, and a bone study in ovariectomised rats.
What is in each capsule
Each capsule carries 25 mg of andarine, which the safety data sheet puts at about 6.2% of the capsule contents by weight. The rest of the fill is microcrystalline cellulose, inside a gelatin shell, and a bottle holds 60. Andarine is classified as a serious eye irritant (H319) and as suspected of damaging fertility or the unborn child (H361); the filler and shell are not classified. The sheet asks for the bottle to be stored locked up, tightly closed in its original container at 15 to 25 °C, dry and out of the light.
What the research covers
Among the first active SARMs
In 2003 Yin and colleagues examined four chiral, nonsteroidal compounds from their laboratory, which bound the androgen receptor with Ki values from 4 to 37 nM1. Only two, S-1 and S-4, worked in castrated rats, where the weights of the prostate and seminal vesicles measured androgenic activity and the weight of the levator ani muscle measured anabolic activity1. Both acted more on the anabolic organ than on the androgenic ones: they were less potent and less effective than testosterone propionate on the prostate and seminal vesicles, but similar to it or stronger on the levator ani1. Near their half-maximal effective levels, neither caused significant suppression of LH or FSH1. The authors called them the first members of a new class of SARMs with selective anabolic effects1.
Bone in ovariectomised rats
Kearbey and colleagues then studied S-4 in 120 female rats in twelve groups, starting at ovariectomy, a model of accelerated bone loss, and continuing for 120 days2. S-4 maintained whole-body and trabecular bone mineral density and cortical content, increased the strength of excised femurs in biomechanical tests, and lowered body fat2. The authors proposed that a SARM could reduce fractures both through bone and by preventing falls through stronger muscles, though falls and strength were not what this study measured2.
What is not established
Everything here is rat work from one research group. Why S-4 favoured the levator ani over the prostate was not settled either: a 2007 review listed tissue distribution, tissue-specific 5α-reductase, ligand-specific gene regulation and tissue-specific coactivators as mechanisms that still had to be sorted out3. No controlled human study of andarine appears in the references, and none of the studies used capsules. The guide to SARMs versus peptides
Frequently asked questions
Is andarine the same compound as S-23?
No. Both are nonsteroidal aryl-propionamide SARMs and share a general framework, but they are different molecules with different formulas and CAS numbers. Their published work also differs: andarine was studied for tissue selectivity and bone, S-23 as a male contraceptive in rats.
What did the castrated-rat studies measure?
Prostate and seminal vesicle weight as markers of androgenic action, and levator ani muscle weight as a marker of anabolic action, each compared with testosterone propionate. A compound that moves the second more than the first is called tissue-selective. These are rat organ weights, not measures of function.
How should the bottle be stored?
Locked up, as the safety data sheet asks, and tightly closed in the original container at 15 to 25 °C, dry and away from light. The capsules need no refrigeration. Andarine is an eye irritant and a suspected reproductive toxicant, which matters most when capsules are opened.
References
- Yin D, Gao W, Kearbey JD, et al. Pharmacodynamics of selective androgen receptor modulators. J Pharmacol Exp Ther. 2003;304(3):1334-40. DOI · PubMed
- Kearbey JD, Gao W, Narayanan R, et al. Selective Androgen Receptor Modulator (SARM) treatment prevents bone loss and reduces body fat in ovariectomized rats. Pharm Res. 2007;24(2):328-35. DOI · PubMed
- Gao W, Dalton JT. Expanding the therapeutic use of androgens via selective androgen receptor modulators (SARMs). Drug Discov Today. 2007;12(5-6):241-8. DOI · PubMed
For laboratory research use only. Not for human or veterinary consumption. Products have not been evaluated by the U.S. Food and Drug Administration and are not intended to diagnose, treat, cure or prevent any disease.