Development of l-CDB-4022 as a nonsteroidal male oral contraceptive: induction and recovery from severe oligospermia in the adult male cynomolgus monkey (Macaca fascicularis)

Endocrinology. 2007 Apr;148(4):1784-96. doi: 10.1210/en.2006-1487. Epub 2007 Jan 11.


The present study was undertaken to examine the antispermatogenic effect of l-CDB-4022 in the adult male cynomolgus monkey. Monkeys (four per group) were dosed via nasogastric tube for 7 d with l-CDB-4022 at 12.5 mg/kg.d or vehicle (d 0=first day of dosing). Plasma levels of l-CDB-4022 and its deesterified metabolite were nondetectable prior to treatment and in all vehicle-treated monkeys. Peak levels of l-CDB-4022 and its metabolite were observed at 4 h after dosing with steady-state levels apparent around d 4. Sperm concentration and total sperm per ejaculate were decreased to levels below 1x10(6) sperm/ml or sperm/ejaculate in l-CDB-4022-treated monkeys by d 17 and remained suppressed through wk 6. Sperm motility also declined to 0% for 6 wk. Testicular volume was reduced in l-CDB-4022-treated monkeys through d 21. The left testis and epididymis were removed from all monkeys on d 24. At this time, the most mature germ cells in the seminiferous tubules of testes from l-CDB-4022-treated monkeys were either spermatocytes or round spermatids. Immature germ cells, but not mature sperm, were found in the efferent ducts and collapsed epididymal lumen of l-CDB-4022-treated monkeys. A steady recovery in sperm motility, concentration, and total sperm per ejaculate was observed in l-CDB-4022-treated monkeys such that these parameters were not different from those of vehicle-treated monkeys by wk 16. Volume of the remaining testis increased in vehicle- and l-CDB-4022-treated monkeys after hemicastration; however, the increase in l-CDB-4022-treated monkeys was delayed compared with that observed in the vehicle-treated monkeys. The morphology of the remaining testis and epididymis, which were removed on wk 17, was normal. Serum inhibin B levels were increased in l-CDB-4022-treated monkeys during the dosing interval; thereafter serum inhibin B levels declined such that there was no difference between the groups by wk 3. l-CDB-4022 treatment did not affect circulating levels of testosterone, LH, FSH, or estradiol. In conclusion, these data indicate that in the cynomolgus monkey, a representative higher primate, l-CDB-4022 exerts a selective antispermatogenic action, which was reversible under the conditions of this study and thus has potential as a nonhormonal oral male contraceptive.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Administration, Oral
  • Animals
  • Contraceptive Agents, Male / administration & dosage
  • Drug Evaluation, Preclinical
  • Epididymis / anatomy & histology
  • Epididymis / drug effects
  • Follicle Stimulating Hormone / blood
  • Indenes / administration & dosage*
  • Indenes / pharmacokinetics
  • Luteinizing Hormone / blood
  • Macaca fascicularis
  • Male
  • Models, Biological
  • Oligospermia / chemically induced*
  • Oligospermia / rehabilitation*
  • Piperidines / administration & dosage*
  • Piperidines / pharmacokinetics
  • Recovery of Function*
  • Testis / anatomy & histology
  • Testis / drug effects
  • Testosterone / blood


  • CDB 4022
  • Contraceptive Agents, Male
  • Indenes
  • Piperidines
  • Testosterone
  • Luteinizing Hormone
  • Follicle Stimulating Hormone