Progress towards hormonal male contraception.

The use of androgens is an essential part of all experimental approaches to hormonal male contraception and involves the suppression of gonadotrophins, leading to inhibition of spermatogenesis. Although clinical trials have proven the concept of hormonal male contraception, their modalities have been unacceptable for practical use for several reasons. Because the efficacy of all self-administered androgen preparations has been disappointing, recent studies have focused on either androgen implants or injectable, long-acting testosterone esters such as testosterone undecanoate. However, in contrast to East Asian men, only two-thirds of Caucasian men respond to such androgen-based regimens with the desired azoospermia (no sperm produced), and thus additional agents are required. Over the past decades various combinations of androgen preparations with different progestins or gonadotrophin-releasing-hormone antagonists have been tested in clinical trials. Of these, testosterone administered in combination with either depot medroxyprogesterone acetate, norethisterone enanthate, desogestrel or etonogestrel have shown promising efficacy.