BMS-564,929 is an investigational selective androgen receptor modulator, which is being developed by Bristol-Myers Squibb for treatment of the symptoms of age-related decline in androgen levels in men ("andropause"). These symptoms may include depression, loss of muscle mass and strength, reduction in libido and osteoporosis. Treatment with exogenous testosterone is effective in counteracting these symptoms but is associated with a range of side effects, the most serious of which is enlargement of the prostate gland, which can lead to benign prostatic hypertrophy and even prostate cancer. This means there is a clinical need for selective androgen receptor modulators, which produce anabolic effects in some tissues such as muscle and bone, but without stimulating androgen receptors in the pr