Androgen therapy adverse effects

When androgen therapy is used in postmenopausal women who complain of poor libido, poor energy, or a feeling of malaise (2), it should be given in association with estrogens, because of its adverse effects on serum lipids. 

Tibolone is an agonist at estrogen and progestogen receptors, with weak androgenic activity. It is given as an alternative to hormone replacement therapy, without added progestogen, and has been in use for some 30 years to treat bone loss in post-menopausal women. Some long-term studies (for example over 10 years) appear to have confirmed its safety and relative freedom from adverse effects (1). In particular there is little or no increase in thrombotic events and the incidence of breast tenderness is low. 

The exact mechanism of this adverse effect is not known. Several cases of priapism have been reported, and it has been hypothesized that androgen therapy probably contributes (107). 

Anastrozole (Fig. 46.11) is a potent and highly selective, nonsteroidal aromatase inhibitor utilized in the treatment of advanced breast cancer that is hormone-responsive. It is considered to be second-line therapy (after tamoxifen) in the treatment of postmenopausal breast cancer. Anastrozole. a benzyltriazole derivative, competes with the natural substrate for binding to the active site of the aromatase. The mechanism of enzyme inhibition resides in the coordination of the triazole ring with the heme iron atom of the aromatase enzyme complex (161,162). This coordination ultimately prevents aromatization of androgens into estrogens and, therefore, deprives the tumor of estrogen. This effect is reversible. In the presence of anastrozole. estradiol levels are reduced to undetectable levels, with no adverse effects on levels of any other hormone, including cortisol and aldosterone. 

---