Efficacy and acceptability of testosterone implants, alone or in combination with a 5alpha-reductase inhibitor, for male hormonal contraception

Contraception. 2000 Aug;62(2):73-8. doi: 10.1016/s0010-7824(00)00139-6.


Testosterone (T) treatment suppresses serum gonadotropins and reduces sperm output sufficiently for contraceptive efficacy in approximately 70% of Caucasian men. In the remaining 30% of men, an increase in 5alpha-reductase activity may maintain testicular androgen activity, thus accounting for the failure of sperm suppression. The form of T therapy is a major consideration in the safety and acceptability of T-based contraception. As compared to T ester injections, T implants provide a more physiological serum T profile and fewer side effects, but have not yet been used in contraceptive efficacy studies. We have used T implants (800-1200 mg every 3 months) in 29 normal men for 3-16 months. T implants produced long-term suppression of sperm densities below 1 million/mL in approximately 70% of men without significant androgenic side effects. No pregnancies occurred in 214 months of exposure. In 16 men failing to suppress within 3 months of T 800 mg, no evidence of enhanced spermatogenic suppression was seen with the co-administration of the type 2 5alpha-reductase inhibitor, finasteride, for 3 months when compared to placebo. We conclude that: 1) T implants provide adequate spermatogenic suppression in approximately 70% of Caucasian men, a rate comparable to intramuscular T injections but with minimal side effects; and, 2) the inclusion of a type 2 5alpha-reductase inhibitor does not enhance spermatogenic suppression.

Publication types

  • Clinical Trial
  • Evaluation Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • 5-alpha Reductase Inhibitors*
  • Adult
  • Contraception*
  • Delayed-Action Preparations
  • Follicle Stimulating Hormone / blood
  • Humans
  • Inhibins / blood
  • Luteinizing Hormone / blood
  • Male
  • Middle Aged
  • Sperm Count
  • Spermatozoa / drug effects
  • Testosterone / administration & dosage*
  • Testosterone / blood


  • 5-alpha Reductase Inhibitors
  • Delayed-Action Preparations
  • Testosterone
  • Inhibins
  • Luteinizing Hormone
  • Follicle Stimulating Hormone