Androgens are physiologically important in the development in male secondary sex characteristics and testicular function. Androgens also have a general anabolic effect. Testosterone has its effect after binding to a specific
androgen receptor. The androgen-receptor complex then binds to a specific androgen responsive element on the DNA in the nucleus, which stimulates the transcription of certain genes.
Hypopituitarism and hypogonadism are the main indications for androgen therapy. Intramuscular administration is 250 mg every 3 weeks. However, this injection results in very high testosterone levels immediately after injection and very low levels just prior to the next injection. Oral administration of testosterone equivalents is usually 120-160 mg daily. The new form of administration via the skin results in the most physiological levels of testosterone.
I. Long-term androgen use in man can inhibit endogenous androgen production. II. Testosterone is the active androgen in the plasma.
Extra info: Due to the negative feedback of androgens on the FSH and LH production and secretion in the pituitary, the endogenous production of androgens and spermatogenesis can be inhibited. Testosterone is converted into the active dihydrotestosterone (DHT) by 5α-reductase.