S4 (Andarine) or Acetamidoxolutamide
Andarine (S-4) is a selective androgen receptor modulator (SARM) studied for its effects on lean muscle mass, strength, and body composition. It is one of the most frequently referenced SARMs in preclinical literature for skeletal-muscle selectivity and metabolic resilience, offering an anabolic-to-androgenic ratio favorable for tissue-specific modeling. EU Pharmaceuticals provides Andarine 12.5 mg reference tablets for laboratory and educational analysis of androgen-receptor binding and selective tissue response.
Key Research Features
- Mechanism: High-affinity binding to androgen receptors (AR) in skeletal-muscle and bone tissue.
- Primary research use: Study of lean-mass retention, muscle-wasting, and metabolic balance models.
- Selectivity: Low prostate stimulation and minimal estrogenic or hepatic interaction.
- Additional findings: Reduction of lipoprotein lipase (LPL) expression and improved vascular density in animal models.
Research Overview
Andarine has been explored as a reference SARM for maintaining lean muscle tissue during caloric deficit. In laboratory models, it demonstrates strong anabolic effects on muscle with reduced androgenic signaling in reproductive tissues. Investigations have also documented improvements in body-fat composition and vascular tone without measurable hepatotoxicity.
Observed Outcomes (Reference Literature)
- Preservation and modest enhancement of lean muscle mass under restricted caloric intake.
- Visible fat-reduction and muscle definition in preclinical studies.
- Improved vascularity and tone associated with AR activation in skeletal tissue.
- No measurable liver enzyme elevation under typical observation ranges.
Findings represent controlled research conditions and are provided for scientific reference only.
Reference Sampling & Handling
- Form: Oral reference tablet (solid dose)
- Content: 12.5 mg Andarine (S-4) per tablet
- Pack size: 56 tablets
- Storage: Store in a cool, dry place (<25 °C) protected from light.
Reference Sampling Protocol
| Observation Phase | Reference Amount | Frequency | Cycle Interval |
|---|---|---|---|
| Baseline (Weeks 1 – 2) | 12.5 mg × 1 daily | Once per 24 h | 7 days/week or 5 days on / 2 off |
| Mid Phase (Weeks 3 – 6) | 12.5 mg × 2 daily (25 mg total) | Split AM / PM | Same schedule |
| Extended (Optional Weeks 7 – 8) | 12.5 – 25 mg daily (as tolerated) | Once per 24 h | 5 days on / 2 off |
Reference Frequency & Safety Notes
- Observation interval: Daily oral administration during 6-week cycles.
- Cycle length: 6 – 8 weeks recommended; include 2 weeks off before repeating.
- Visual adaptation effects: Yellow hue or reduced night-vision sensitivity have been reported at higher exposures (>50 mg/day) and resolve upon discontinuation.
- Titration management: If visual effects occur, implement a 5-on / 2-off sampling schedule.
- No aromatization or hepatic activation reported in assay literature.
All values represent reference-sampling models derived from S-4 academic publications and are not intended as clinical guidance.
Mechanism of Action (Research Summary)
- Androgen Receptor Modulation: Selective activation in skeletal muscle and bone.
- Metabolic Impact: Downregulates fat-storage enzyme LPL and supports lipid metabolism modeling.
- AR Selectivity: Minimal effect on prostate or secondary sexual organs.
- Cardiovascular Findings: Maintains stable LDL / HDL ratio across test ranges.
Stacking (Research Synergy)
- With Cardarine (GW-501516): For endurance and metabolic synergy models.
- With Nutrobal (MK-677): For growth-hormone secretagogue and recovery models.
- With Ostarine (MK-2866): For balanced anabolic and recovery-phase evaluation.
What’s in the Box
- 56 × Andarine 12.5 mg tablets
Why Choose EU Pharmaceuticals?
EU Pharmaceuticals provides laboratory-verified SARMs manufactured to analytical standards. Each batch is HPLC-tested and MS-verified to confirm purity, concentration, and structural integrity for reliable research replication.
For laboratory, educational, and research use only. Not for human or veterinary ingestion or therapeutic application. No medical or performance claims are made or implied. Buyer assumes responsibility for lawful handling and regulatory compliance.
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