Maintenance of spermatogenic suppression by etonogestrel implants with
depot testosterone
M. Walton (1), B. Brady (1), D.T. Baird (1), R.A. Anderson (2)
Contraceptive Development Network, Edinburgh, UK (1); MRC Human
Reproductive Sciences Unit, Centre for Reproductive Biology, University of
Edinburgh, UK
Objective: Testosterone/progestogen combinations are currently the
most promising approach to hormonal male contraception. We here investigated the
effectiveness of the etonogestrel implant Implanon® in combination with
androgen replacement using testosterone pellets in maintaining spermatogenic
suppression. We have recently demonstrated that this combination results in
profound but incomplete suppression of spermatogenesis with only 1/14 men
maintaining a sperm concentration >0.1×106/ml after 24 weeks
treatment with 2 etonogestrel implants. We here investigated the effects of a
higher dose of etonogestrel, i.e. 3 implants at maintaining spermatogenic
suppression for a longer time period of up to 48 weeks.
Methods: Fifteen healthy men received 3 subcutaneous etonogestrel
implants (each releasing approximately 50 µg/day) with 400mg testosterone
pellets s. c. 12- weekly for 24 or 48 weeks. Semen analysis was performed at 4
weekly intervals.
Results: 13 of 15 men completed 24 weeks treatment. Sperm
concentrations were reduced to <1x106/ml in all 14 subjects at
week 16. Azoospermia was achieved in 10/14 subjects at week 16 and 10/13
subjects at week 24. 9 men chose to continue treatment to a total of 48 weeks. 8
men remained consistently azoospermic from week 28, but one showed partial
recovery of spermatogenesis from week 40, sperm concentration increasing from
azoospermia to 7×106/ml. This was associated with partial escape from
suppression of FSH. LH remained suppressed to the limit of detection in all men.
Mean testosterone concentrations remained in the normal range throughout the
study.
Conclusion: In comparison to 2 etonogestrel implants with testosterone
pellets, the addition of a third provides more consistent profound suppression
of gonadotrophins and spermatogenesis. This regimen therefore illustrates the
potential for long-acting hormonal male contraception, although the duration of
action remains to be more completely defined.
This study was supported by DFID/MRC (grant no G9523250).
