No male hormonal contraceptive is ready for clinical use. Most trials were small exploratory studies. Their power to detect important differences was limited and their results imprecise. In addition, assessment of azoospermia can vary by sensitivity of the method used. Future trials need more attention to the methodological requirements for RCTs. More trials with adequate power would also be helpful.
Oral progestogen combined with testosterone as a potential male contraceptive: additive effects between desogestrel and testosterone enanthate in suppression of spermatogenesis, pituitary-testicular axis, and lipid metabolism.
The effects of a synthetic oral progestogen, desogestrel (DSG), administered with low dose testosterone (T) were investigated to determine the optimal combination for suppression of gonadotropins and spermatogenesis to targets compatible with effective male contraception. Twenty-four healthy male volunteers (33.2 +/- 0.9 yr) were randomly assigned to 3 groups (n = 8) to receive: 1) 300 microg DSG orally daily and 100 mg T enanthate, i.m., weekly; 2) 300 microg DSG and 50 mg T enanthate; or 3) 150 microg DSG and 100 mg T enanthate for 24 weeks. To investigate the individual contribution to the combined action, DSG was administered alone for the first 3 weeks, and T enanthate was added on day 22. After 24-week treatment, sperm density in 78% (18 of 23) of the subjects became azoospermic, whereas 91.7% (22 of 24) and 95.8% (23 of 24) suppressed to less than 1 million/mL and less than 3 million/mL, respectively. The 300 microg DSG with 50 mg T enanthate combination induced azoospermia in 8 of 8 subjects, and the suppression of sperm density was significantly greater than that in the 300 microg DSG/100 mg T enanthate group, but was not different from that in the 150 microg DSG/100 mg T enanthate group. DSG (300 or 150 microg daily) alone in the first 3 weeks suppressed LH, FSH, and T to 60.6%, 48.0%, and 35.4%, respectively, of the baseline. Addition of T enanthate (50 and 100 mg weekly) raised plasma T to the physiological range and induced a further fall in LH and FSH to the limits of assay detection. There was no consistent difference in mean LH and FSH levels among the three groups during treatment or recovery, except that FSH remained detectable in a higher proportion of samples from the group receiving 300 microg DSG with 50 mg T enanthate. Total cholesterol, high density lipoprotein cholesterol, and low density lipoprotein cholesterol decreased by 9.3 +/- 1.7%, 10.3 +/- 2.6%, and 7.7 +/- 2.8%, respectively, during treatment with DSG alone with no difference between 300 and 150 microg. Addition of T enanthate (both 50 and 100 mg weekly) induced a further fall only in high density lipoprotein cholesterol to 22.6 +/- 3.7% from the baseline. In summary, the combined actions of oral DSG with low doses of T enanthate were highly effective in suppressing pituitary-testicular functions in adult men. The optimal regimen for inducing azoospermia was 300 microg DSG daily with 50 mg T enanthate weekly. Oral DSG exerted discernible effects on lipid metabolism. We conclude that the combination of oral progestogens with low dose T is a promising approach to achieve effective reversible male contraception.