S-4 (Andarine)

S-4 (Andarine) Research Standard

S-4 (Andarine / GTx-007) is a synthetic nonsteroidal selective androgen receptor modulator (SARM) belonging to the arylpropionamide chemical class. As one of the early Selective Modulators to advance into clinical research, it provides a well-documented benchmark for studying AR-mediated anabolic effects and tissue-specific ligand activity. In laboratory research, S-4 is valued not only for its high-affinity androgen receptor binding but also for its unique partial-agonist profile and documented interaction with visual physiological pathways, making it a critical reference compound for both androgen pharmacology and off-target signaling research.

Technical Specifications

Mechanism of Action & Research Context

S-4 is characterized as a partial agonist at the androgen receptor (AR), eliciting tissue-differential transcriptional outputs that distinguish it from full-agonist ligands.

• Partial Agonist Profile: Unlike full agonists, S-4 exhibits reduced transcriptional activity in prostate-derived reporter models while maintaining high anabolic activity in muscle and bone tissue models. This “tissue-selective” property is a primary focus of AR pharmacological research.

• Receptor Binding: With a reported ki of approximately 4 nM, S-4 is a high-affinity ligand for the AR ligand-binding domain. Its interaction is utilized to study the conformational shifts required for receptor transactivation.

• Visual System Research: S-4 is uniquely noted in the research literature for its interaction with retinal photoreceptor signaling, which manifested as dose-limiting “yellow-tinged vision” in clinical research. Consequently, it is a rare reference compound for investigating off-target effects of AR ligands on visual physiology.

Research Applications

S-4 is a specialized reagent essential for comparative pharmacological and analytical studies.

Primary fields of in vitro laboratory investigation include:

• Comparative Pharmacology: Serving as a comparative ligand alongside other arylpropionamides (e.g., MK-2866, S-23) to assess potency, efficacy, and binding dynamics.

• Analytical Method Development: Providing a standardized analyte for LC-MS/MS and forensic identification protocols, particularly in the context of anti-doping research.

• Visual Physiology Models: Investigating the molecular mechanisms underlying the interaction between SARMs and retinal signaling pathways.

• Structure-Activity Relationship (SAR) Studies: Evaluating how the specific 4-acetamido and 4-nitro substituent patterns influence receptor selectivity and agonist potency.

• BPH & Muscle Wasting Models: Modeling the reduction of prostate weight and muscle preservation pathways in preclinical and in vitro settings.

Storage & Handling Guidelines

To maintain the chemical stability and experimental reliability of the compound:

• Long-Term Storage: Store in a dry, cool environment. Maintain at -20 °C for extended stability.

• Environmental Control: Protect from direct light. Ensure the container is kept tightly sealed to prevent atmospheric moisture uptake.

• Aseptic Technique: Utilize clean, non-reactive laboratory tools during weighing to prevent cross-contamination.

• Handling Hygiene: Adhere to standard laboratory safety protocols, as S-4 is a potent research-grade ligand.

Regulatory & Research Note

S-4 has been included on the World Anti-Doping Agency (WADA) Prohibited List since 2008. In analytical chemistry, it is a high-priority target for forensic toxicology method validation. It is not approved for any human, veterinary, or clinical use, and all research must be conducted in strict compliance with applicable institutional and legal standards.

Research Use Disclaimer

Research Use Only Disclaimer: This product is developed and distributed strictly as a Research Use Only (RUO) laboratory reference chemical intended exclusively for non-clinical analytical and scientific investigation. It is not an FDA-approved drug, medical treatment, dietary supplement, or food ingredient, and is strictly prohibited for human or animal consumption. Kimera Chems supplies this high-purity research material solely to qualified institutions and professional investigators for authorized laboratory research.