Testosterone Undecanoate

Endogenous androgens, including testosterone and dihydrotestosterone (DHT), are responsible for the normal growth and development of the male sex organs and for maintenance of secondary sex characteristics. These effects include the growth and maturation of prostate, seminal vesicles, penis and scrotum; the development of male hair distribution, such as facial, pubic, chest and axillary hair; laryngeal enlargement, vocal cord thickening, alterations in body musculature and fat distribution.Male hypogonadism, a clinical syndrome resulting from insufficient secretion of testosterone, has two main etiologies. Primary hypogonadism is caused by defects of the gonads, such as Klinefelter's Syndrome or Leydig cell aplasia, whereas secondary hypogonadism is the failure of the hypothalamus (or pituitary) to produce sufficient gonadotropins (FSH, LH).Testosterone plays a key role in male sexual differentiation and is involved in regulation of hematopoiesis, body composition, and bone metabolism. As a result, Testosterone replacement therapy in males with hypogonadism can result in improved sexual function, increased lean body mass, bone density, erythropoiesis, prostate size, and changes in lipid profiles.Testosterone is produced by Leydig cells and exerts it's effects by binding to androgen receptors throughout the body. Testosterone affects the voice, genitalia, mood, and influences muscle growth and protein expression. Accordingly, males with low levels of Testosterone often experience decreased libido, fatigue, mood changes and dysphoria. Exogenous sources of Testosterone are designed to mimic the effects of endogenous Testosterone.