S23 | S-23 SARM Solution 20mg/ml – 50ml

S23 | S-23 SARM Solution 20mg/ml – 50ml

What Is S-23?

S-23 is a non-steroidal selective androgen receptor modulator (SARM) developed by GTX Inc. as a potential male hormonal contraceptive. It is one of the most androgenically potent SARMs characterized, with high binding affinity for the androgen receptor and near-complete suppression of LH and FSH at higher doses in animal models — a profile that makes it uniquely interesting for both contraception research and comparative pharmacology studies at the strong end of the SARM potency spectrum.

Unlike partial agonists such as Ostarine (MK-2866), S-23 acts as a full AR agonist in most tissues, producing robust anabolic responses in muscle and bone while also demonstrating significant androgenic activity in reproductive tissues. This places S-23 at the opposite end of the SARM selectivity spectrum from Ostarine, making them natural comparative tools in receptor selectivity research.

Mechanism of Action

S-23 binds the androgen receptor with very high affinity and acts as a full agonist in muscle and bone. Its high tissue penetration and strong receptor engagement produce potent anabolic effects alongside significant HPG axis suppression — including near-total suppression of FSH and LH in rat models, leading to infertility via reduced sperm production. Critically, this suppression is reversible upon cessation, which is a prerequisite for any contraceptive application. S-23 has been studied alongside progestins in male contraceptive animal models to examine combination regimens.

Research Applications

• Male hormonal contraception: Near-complete spermatogenesis suppression via FSH/LH suppression, with reversibility upon cessation.
• SARM potency benchmarking: Used as the high-affinity, high-androgenicity reference point in comparative SARM panels.
• Muscle and bone anabolism: Dose-dependent lean mass and bone mineral density effects characterized in rodent models.
• AR pharmacology: Full agonist at both muscle/bone and androgenic tissues — useful for studying the limits of tissue selectivity.

Related Research Compounds

S-23 is positioned at the high-androgenicity end of the SARM spectrum. Its contrasting selectivity profile compared to Andarine (S4) and Ostarine makes it valuable in selectivity studies alongside RAD-140 and LGD-4033. For dual-mechanism anabolic studies, it is sometimes combined with MK-677 (Ibutamoren).

For laboratory research use only. Not for human or animal consumption.