Maintenance of spermatogenic suppression by etonogestrel implants with depot testosterone

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


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).

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