[Show abstract][Hide abstract] ABSTRACT: This study was performed to assess spermatogenesis suppression and safety of a new combination of an etonogestrel (ENG) implant combined with testosterone undecanoate (TU) injections for male contraception. This is the first large placebo-controlled study for male hormonal contraception. DESIGN AND STUDY SUBJECTS: In this double-blind, multicenter study, we randomly assigned 354 healthy men to receive either a low- or high-release ENG implant sc combined with im TU injections (750 mg every 10 or 12 wk or 1000 mg every 12 wk) or placebo implant and injections. Treatment duration was 42 or 44 wk and posttreatment follow-up at least 24 wk.
Overall, spermatogenesis was suppressed to 1 million/ml or less at wk 16 in 89% of men, with approximately 94% in two high-release ENG groups. Suppression was maintained up to the end of the treatment period in 91% of men. For all men who completed the treatment period, 3% never achieved 1 million/ml or less. Median recovery time to a sperm concentration above 20 million/ml was 15 wk (mean 17 wk, 95% confidence interval 16-18 wk). Treatment was well tolerated. As compared with the placebo group, more men in the active treatment groups reported adverse events such as weight gain, mood changes, acne, sweating, or libido change. For both spermatogenesis suppression and safety, differences were small between the active treatment groups.
The combination of an ENG implant with TU injections is a well-tolerated male hormonal method, providing effective and reversible suppression of spermatogenesis. Although the results are good, there is still room for improvement, possibly by adjusting the dose regimen or changing the mode of application.
Full-text · Article · Aug 2008 · Journal of Clinical Endocrinology & Metabolism
[Show abstract][Hide abstract] ABSTRACT: Male hormonal contraceptive methods require effective suppression of sperm output.
The objective of the study was to define the covariables that influence the rate and extent of suppression of spermatogenesis to a level shown in previous World Health Organization-sponsored studies to be sufficient for contraceptive purposes (< or =1 million/ml).
This was an integrated analysis of all published male hormonal contraceptive studies of at least 3 months' treatment duration.
Deidentified individual subject data were provided by investigators of 30 studies published between 1990 and 2006.
A total of 1756 healthy men (by physical, blood, and semen exam) aged 18-51 yr of predominantly Caucasian (two thirds) or Asian (one third) descent were studied. This represents about 85% of all the published data.
Men were treated with different preparations of testosterone, with or without various progestins.
Semen analysis was the main measure.
Progestin coadministration increased both the rate and extent of suppression. Caucasian men suppressed sperm output faster initially but ultimately to a less complete extent than did non-Caucasians. Younger age and lower initial blood testosterone or sperm concentration were also associated with faster suppression, but the independent effect sizes for age and baseline testicular function were relatively small.
Male hormonal contraceptives can be practically applied to a wide range of men but require coadministration of an androgen with a second agent (i.e. progestin) for earlier and more complete suppression of sperm output. Whereas considerable progress has been made toward defining clinically effective combinations, further optimization of androgen-progestin treatment regimens is still required.
Full-text · Article · Jun 2008 · Journal of Clinical Endocrinology & Metabolism