High-Quality STROMUSC Andarine S4 25mg For Bodybuilding CAS:401900-40-1

   What Andarine S4 Actually Is

    Andarine is a non-steroidal, orally active selective androgen receptor modulator from the aryl-propionamide chemical class. Its molecular formula is C₁₇H₁₆F₃N₃O₆ with a molecular weight of approximately 441.35 g/mol. The scaffold is structurally derived from the antiandrogen bicalutamide-a drug used to treat prostate cancer-through a series of modifications that converted a pure antagonist into a tissue-selective partial agonist.

    The technical distinction matters: S4 is not a full agonist like testosterone. It produces submaximal signalling even when the receptor is fully occupied. This partial agonist profile is what gives it tissue selectivity-different tissues respond differently based on their coactivator and corepressor environments. In practical terms, muscle and bone get the anabolic signal; prostate and skin get a fraction of it.

    Oral bioavailability is approximately 80% at low doses, making it viable for oral administration. Unlike many androgens, S4 does not convert to dihydrotestosterone and does not aromatize to estrogen. There is no estrogenic activity to manage-no water retention, no gynecomastia risk from estrogen conversion.

    The 25mg tablet represents the standard unit dose for Andarine. Most commercially available products present S4 in 25mg capsules or tablets, typically supplied in 60-count bottles-a six-to-eight-week supply at standard dosing. The tablet formulation offers several practical advantages over liquid suspensions: precise dosing, longer shelf stability when stored properly at room temperature in sealed containers away from light, and elimination of the solvent taste issues associated with liquid SARMs.

    For a user weighing under 80kg (approximately 176 lbs), 25mg daily is often cited as the entry-level dose. For those above 85kg, the typical recommendation increases to 50mg daily, typically split into two administrations.

    Tissue-Selective Androgen Receptor Modulation

    S4 docks onto the androgen receptor with high affinity-about 4 nanomolar-but its partial agonist activity means the downstream transcriptional response varies by tissue type. In skeletal muscle, it drives anabolic signalling: increased protein synthesis, enhanced nitrogen retention, and muscle fibre preservation. In bone, it promotes mineral density. In prostate and skin, the signal is dampened. This is the core of its appeal.

    Non-Aromatising, Non-5α-Reducing

    S4 does not convert to estrogen via aromatase, nor does it reduce to dihydrotestosterone via 5α-reductase. This eliminates estrogenic side effects-gynecomastia, water retention, high blood pressure from fluid shifts-and reduces androgenic side effects like prostate enlargement and scalp follicular miniaturisation.

    Short Half-Life, Frequent Dosing Required

    The plasma half-life of Andarine is short-approximately 4 to 6 hours, with some sources citing 2.6 hours and others up to 5.3 hours. This is the single most important pharmacokinetic parameter governing how the compound is used. Unlike Ostarine with its ~24-hour half-life, S4 requires split dosing to maintain stable blood concentrations.

    Peak Plasma Concentration

    Time to peak concentration is approximately 1.5 hours post-administration, with an active duration of about 6 hours. The compound is metabolised in part via hydrolysis of the acetamido group.

    Cutting Cycles

    Andarine is predominantly discussed in cutting contexts. Its primary value during a caloric deficit is muscle preservation-preventing the catabolic erosion of lean tissue that typically accompanies aggressive dieting. Users report maintaining or even slightly increasing strength while dropping body fat, which is unusual during a cut.

    The visual effects are distinctive: S4 produces a "dry" look, with water driven out from beneath the skin, enhanced vascularity, and a harder, more grainy muscle appearance. This is why it is often described as a "finishing compound"-something to run in the final weeks before a photoshoot, competition, or any situation where cosmetic appearance matters.

    Body Recomposition

    Some users employ S4 for recomping-simultaneous fat loss and lean mass gain. The compound's ability to preserve muscle in a deficit while promoting fat utilisation makes it suitable for this purpose. Users typically report body fat reductions in the range of 3–5% while maintaining muscle fullness.

    Strength Retention

    Even in a calorie-restricted state, S4 helps maintain lifting capacity. Users frequently note that their working weights remain stable or increase slightly throughout a cycle. This is not the dramatic strength surge associated with compounds like RAD-140 or anabolic steroids, but rather preservation of what you already have.

    Stacking

    S4 is commonly stacked with other compounds. The classic cutting stack combines S4 with Ostarine (for additional muscle preservation) and Cardarine (GW-501516) for enhanced endurance and fat oxidation. It can also be used alongside low-dose anabolics as a finishing compound in the last six weeks of a cycle.

    Muscle Preservation in Deficit

    This is the primary benefit. When calories are restricted, the body naturally shifts toward catabolism. S4 signals the androgen receptor in muscle tissue to maintain protein synthesis, effectively telling the body to spare muscle even as fat is mobilised for fuel.

    Enhanced Vascularity and "Hardening"

    The cosmetic effects are pronounced. S4 drives water out from beneath the skin, producing a paper-thin appearance with visible veins and striations. This is not water manipulation through diuretics-it is a genuine shift in fluid dynamics mediated through androgen receptor signalling.

    Bone Density Support

    S4 selectively targets bone tissue, improving skeletal mineral density. For lifters handling heavy loads, this provides joint protection and may reduce injury risk.

     No Estrogenic Side Effects

    Because S4 does not aromatise, there is no water retention, no bloating, and no risk of estrogen-driven gynecomastia. This makes it appealing for users who want the anabolic effects without the "puffy" look associated with aromatising compounds.

    Strength Maintenance

    Users consistently report that their strength holds steady throughout a cycle. In a cutting phase where strength typically drops, this is a significant advantage.

    Entry-Level: 25mg Daily

    The 25mg daily dose is where most beginners start. This dose allows the user to assess tolerance-particularly regarding visual side effects-without committing to higher exposure. For the first week, regardless of experience with other SARMs, starting at 25mg/day is recommended.

    Standard Dose: 50mg Daily

    The most commonly used dose in the bodybuilding community is 50mg per day. At this level, the visual and aesthetic effects become pronounced. Strength is maintained. Body composition shifts become noticeable within two to three weeks.

    Split Dosing Protocol

    Because the half-life is only 4–6 hours, splitting the daily dose is essential. A typical protocol divides 50mg into two 25mg administrations: one in the morning and one approximately 4–6 hours later, ideally pre-workout. Some users split into three doses for even more stable blood levels.

    For the 25mg tablet formulation, this means taking one tablet upon waking and one tablet in the afternoon or before training.

    Advanced Dosing: 50–75mg Daily

    More experienced users sometimes push to 75mg daily, though this increases the likelihood and severity of visual side effects. At doses above 50mg, vision disturbances become more common and more pronounced.

    What the 25mg Tablet Delivers

    Each 25mg tablet provides a precise, pre-measured dose. For a user running 50mg daily, this means two tablets per day. For a user at 25mg daily, one tablet per day. The tablet form eliminates the measuring errors associated with liquid droppers.

    Standard Duration: 6 to 8 Weeks

    The typical Andarine cycle runs 6 to 8 weeks. This duration balances results against suppression: long enough to see meaningful changes, short enough to limit hypothalamic-pituitary-testicular axis (HPTA) suppression and minimise side effect accumulation.

    Extended Cycles: 8 to 12 Weeks

    Some protocols extend to 8–12 weeks, particularly at lower doses. However, suppression becomes more pronounced with longer duration, and the visual side effects tend to accumulate over time.

    Cycle Off Period

    Between cycles, a rest period equal to the cycle length plus post-cycle therapy duration is standard practice. For a 6–8 week cycle with 4 weeks of PCT, this means approximately 10–12 weeks off before starting another cycle.

    The half-life of Andarine is approximately 4 hours, with a range of 2.6 to 6 hours reported across different sources. This short half-life has practical implications:

    Split Dosing Is Mandatory

    A single daily dose would produce a sharp peak followed by rapid decline, leaving the user with sub-therapeutic levels for much of the day. Splitting the dose into two or three administrations maintains more stable blood concentrations.

    Timing Around Training

    Taking a dose approximately 1.5 hours pre-workout aligns with the time to peak plasma concentration. This means the compound is at its highest level during the training window, when androgen receptor signalling can most directly support performance.

   Morning and Afternoon Schedule

    A typical two-dose schedule: 25mg upon waking, 25mg 4–6 hours later. For a user training in the evening, the second dose might be taken mid-afternoon to peak around training time.

    No Accumulation

    The short half-life means the compound does not accumulate significantly in the body. Steady state is reached quickly, and clearance is relatively rapid upon discontinuation.

    Why PCT Is Required

    Andarine suppresses endogenous testosterone production. The degree of suppression is dose-dependent-higher doses and longer cycles produce more suppression. Even at 25mg daily, some suppression occurs, though anecdotal reports suggest it may be minimal at this level. At 50mg daily for 6–8 weeks, suppression is significant enough to warrant a structured PCT.

    SERM-Based PCT

    The standard PCT protocol for Andarine uses a selective estrogen receptor modulator (SERM) such as Nolvadex (tamoxifen) or Clomid (clomiphene). A typical Nolvadex protocol is 20mg daily for 3–4 weeks post-cycle.

    Timing

    PCT begins the day after the last Andarine dose. The short half-life means S4 clears the system within approximately 24 hours, allowing the SERM to begin stimulating the HPTA without interference.

    Monitoring

     Lipid profiles should be monitored mid-cycle-HDL suppression is expected with SARM use. Liver values should also be checked, though S4 is considered relatively mild on the liver compared to oral steroids.

    Over-the-Counter Options

    Some users employ over-the-counter test boosters instead of pharmaceutical SERMs. However, for a 50mg, 8-week cycle, pharmaceutical SERMs provide more reliable HPTA restoration.

    The defining characteristic of Andarine-and the reason it was abandoned clinically-is its dose-dependent effect on vision. At doses above 50mg daily, users commonly report:

    ●A yellow-green tint to vision

    ●Slowed adaptation from bright to dark environments and vice versa

    ●Difficulty seeing in low light conditions

    These effects are generally reversible upon cessation. However, the mechanism is not fully understood, and the fact that a pharmaceutical company terminated development specifically because of this side effect should give any user pause.

    At 25mg daily, visual disturbances are less common but still possible in sensitive individuals. Starting at 25mg allows the user to assess their personal response before escalating.

Brand	STROMUSC
Trade names	Acetamidoxolutamide; Androxolutamide; GTx-007; S-4
CAS	401900-40-1
Molar mass	441.363
Formula	C19H18F3N3O6
Purity	Above 98%
Apprarance	25mg*100

 

 

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    Andarine S4 is a compound of trade-offs. It delivers visible, cosmetic results-hardness, dryness, vascularity-that few other SARMs can match. It preserves muscle during aggressive cutting in ways that natural dieting cannot replicate. It does all of this without the estrogenic side effects or liver strain of oral steroids.

    But the trade-offs are real. The vision side effects are not theoretical-they are the reason this compound was abandoned by its developers. The suppression requires PCT. The short half-life demands disciplined split dosing. And the regulatory status means every purchase is a gamble on purity and quality.

    For the informed user who understands these trade-offs, who starts low and titrates carefully, who monitors their response and respects the cycle length, Andarine S4 can deliver results that justify its reputation. But it is not a compound to be taken lightly-and it is certainly not a substitute for the fundamentals of nutrition, training, and recovery that underpin all real progress in bodybuilding.

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