Potential of norethisterone enanthate for male contraception:: pharmacokinetics and suppression of pituitary and gonadal function

OBJECTIVE Gestagens are known to suppress gonadotrophins in women and are currently also under investigation for the development of hormonal male contraceptives. The aim of the study was to assess the potential of norethisterone enanthate (NETE) for male contraception. DESIGN AND MEASUREMENTS The suppressive effect of a single injection of 200 mg NETE on serum gonadotrophins, serum testosterone, lipids, spermatogenesis, well-being and sexual function was evaluated in seven healthy men. RESULTS In this single dose study treatment was well tolerated by ail volunteers. NETE led to a rapid, profound and significant suppression of serum LH (day 6 - day 10), FSH (day 2 - day 29), testosterone (day 1 - day 29 and day 35) and SHBG (day 6 - day 35), At study end sperm counts were significantly suppressed, Numbers of spontaneous erections (day 17, 23 and 26), number of sexual fantasies (day 20 and 23) as well as libido (day 20 and 26) were significantly decreased compared to baseline. Ail other parameters including lipids, augmented glucose, testicular volume and well-being showed no significant alterations, CONCLUSION Because of its strong, rapid and sustained suppression of serum FSH and testosterone norethisterone enanthate offers great potential for hormonal male contraception if combined with testosterone esters.