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A scientific study published in 2005 examined the effects of Andarine S-4 in the skeletal muscles, bones and pituitary glands of castrated male rats. 12 weeks after castration, animals were treated with Andarine (3 or 10 mg/kg), dihydrotestosterone (DHT) (3 mg/kg), or vehicle for 8 weeks.

Andarine (doses 3 and 10 mg/kg) restored soleus muscle mass and strength and levator ani muscle mass to that seen in intact animals. Similar changes were also observed in DHT-treated (3 mg/kg) animals. Compared with the anabolic effects observed in muscle, DHT (3 mg/kg) stimulated prostate and seminal vesicle weights moire than 2-fold greater than that observed in intact controls, whereas Andarine (3 mg/kg) returned these androgenic organs to only 16 and 17%, respectively, of the control levels. Andarine (3 and 10 mg/kg) and DHT (3 mg/kg) restored castration-induced loss in lean body mass.

Furthermore, Andarine treatment caused a significantly larger increase in total body bone mineral density than DHT. Andarine S-4 (3 and 10 mg/kg) also demonstrated agonist activity in the pituitary and significantly decreased plasma LH and FSH levels in castrated animals in a dose-dependent manner. In summary, the strong anabolic effects of Andarine S-4 in skeletal muscle, bone, and pituitary were achieved with minimal pharmacologic effect in the prostate.


In another scientific study, the skeletal effects of Andarine S-4 on osteopenic rats were investigated. Aged female rats were gonadectomized or sham operated on day 1 and assigned to treatment groups. Dosing was initiated on day 90 and continued daily until day 210. Whole animal bone mineral density (BMD), body weight, and fat mass were determined by dual energy x-ray absorptiometry (DEXA). Regional analysis of excised bones was performed using DEXA or computed tomography. Femur strength was evaluated by 3-point bending. Andarine restored whole body and lumbar vertebrae (L5-L6) BMD to the level of intact controls. Significant increases in cortical bone quality were observed at the femoral midshaft, resulting in increased load bearing capacity.

Andarine demonstrated partial/complete recovery of bone parameters to age-matched intact levels. Increased efficacy observed in cortical bone sites is consistent with reported androgen action in bone. The ability of Andarine to promote bone anabolism, prevent bone resorption, and increase skeletal muscle mass/strength has shown that Andarine may be especially beneficial in osteoporosis and overall, SARMs are promising new alternatives for the treatment of osteoporosis.


Andarine S-4 may be useful also in the treatment of benign prostatic hyperplasia (BPH), because it is able to competitively block binding of Dihydrotestosterone (DHT) to its receptor targets in the Prostate gland. The advantage of Andarine over traditionally used antiandrogens for the treatment of benign prostatic hyperplasia is that Andarine, thanks to its partial agonist effects on androgen receptor (AR), at the same time prevent the side effects that often occur in the treatment of benign prostatic hyperplasia with antiandrogens.


Benign prostatic hyperplasia (also called benign prostatic hypertrophy or abbreviated only BPH) is a noncancerous increase in size of the prostate gland. In the prostate gland, the enzyme 5-alpha-reductase type II metabolizes circulating testosterone into DHT, which works locally, not systemically. Subsequently, DHT binds to androgen receptors in the cell nuclei, potentially resulting in BPH.

Symptoms may include frequent urination, trouble starting to urinate, weak stream, inability to urinate, or loss of bladder control. Complications can include urinary tract infections, bladder stones, and chronic kidney problems.


Antiandrogens, also known as androgen antagonists or testosterone blockers, are a class of drugs that prevent androgens like testosterone and dihydrotestosterone (DHT) from mediating their biological effects in the body. They act by blocking the androgen receptor (AR) and/or inhibiting or suppressing androgen production. The most widely used antiandrogen (androgen receptor antagonist) in the treatment of prostate cancer is Bicalutamide.

Antiandrogens can be thought of as the functional opposites of AR agonists (androgen receptor agonists are, for example, testosterone, DHT, anabolic steroids or SARMs). Antiandrogens are one of three types of sex hormone antagonists, the others being antiestrogens and antiprogestogens.

Side effects of antiandrogens depend on the type of antiandrogen and the specific antiandrogen in question. Common side effects of antiandrogens in men include breast tenderness, breast enlargement, feminization, hot flashes, sexual dysfunction, infertility, and osteoporosis. In women, common side effects of antiandrogens include low estrogen levels and associated symptoms like hot flashes, menstrual irregularities, and osteoporosis in premenopausal women.


    • Andarine has anabolic effects in skeletal muscle, bone, and pituitary
    • Andarine is able to competitively block binding of DHT to its receptor targets
    • Andarine can help treat serious diseases associated with muscle loss
    • Andarine may be especially beneficial in osteoporosis
    • Andarine may be useful in the treatment of BPH (benign prostatic hypertrophy)
    • Andarine helps build and maintain muscles
    • Andarine promotes bone anabolism, prevents bone resorption
    • Andarine can help protect the prostate from benign prostatic hypertrophy
    • Andarine can help prevent hair loss and androgenic alopecia (baldness)


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