title: Progress and prospects in male hormonal contraception.
abstract: OBJECTIVE
  Testosterone functions as a contraceptive by suppressing the secretion of luteinizing hormone and follicle-stimulating hormone from the pituitary. Low concentrations of these hormones deprive the testes of the signals required for spermatogenesis and results in markedly decreased sperm concentrations and effective contraception in a majority of men. Male hormonal contraception is well tolerated and acceptable to most men. Unfortunately, testosterone-alone regimens fail to completely suppress spermatogenesis in all men, meaning that in some the potential for fertility remains.
  
  
  RESULTS
  Because of this, novel combinations of testosterone and progestins, which synergistically suppress gonadotropins, have been studied. Two recently published testosterone/progestin trials are particularly noteworthy. In the first, a long-acting injectable testosterone ester, testosterone decanoate, was combined with etonogestrel implants and resulted in 80-90% of subjects achieving a fewer than 1 million sperm per milliliter. In the second, a daily testosterone gel was combined with 3-monthly injections of depot medroxyprogesterone acetate producing similar results.
  
  
  CONCLUSIONS
  Testosterone-based hormone combinations are able to reversibly suppress human spermatogenesis; however, a uniformly effective regimen has remained elusive. Nevertheless, improvements, such as the use of injectable testosterone undecanoate, may lead to a safe, reversible and effective male contraceptive.
authors.affiliation: Center for Research in Reproduction and Contraception, Department of Medicine, University of Washington, Seattle, Washington 98195, USA. jamory@u.washington.edu
authors.forename: John K
authors.initials: JK
authors.lastname: Amory
mesh_terms: D003267:Contraception / Q000379:methods; D003272:Contraceptive Agents, Male / Q000008:administration & dosage*; D017135:Desogestrel / Q000008:administration & dosage; D006801:Humans; D008297:Male; D017258:Medroxyprogesterone Acetate / Q000008:administration & dosage; D009845:Oligospermia / Q000139:chemically induced; D013076:Sperm Count; D013091:Spermatogenesis / Q000187:drug effects*; D013092:Spermatogenesis-Blocking Agents / Q000008:administration & dosage; D013739:Testosterone / Q000008:administration & dosage / Q000031:analogs & derivatives; D016896:Treatment Outcome
chemical_list: D003272:Contraceptive Agents, Male; D013092:Spermatogenesis-Blocking Agents; C044815:etonogestrel; D013739:Testosterone; D017135:Desogestrel; D017258:Medroxyprogesterone Acetate; C041677:testosterone decanoate