title: Low dose gossypol for male contraception.
abstract: OBJECTIVE
  To ascertain whether the side effects of gossypol, hypokalemia and irreversibility, could be avoided on dose reduction.
  
  
  METHODS
  Seventy-seven male volunteers were divided into 3 groups: control (22 cases), 10 mg gossypol (29 cases) and 12.5 mg (26 cases). Serum levels of testosterone, FSH and LH were measured by RIA and potassium by flame photometry. Sperm counts and motility were examined before and regularly after treatment for the evaluation of contraceptive efficacy.
  
  
  RESULTS
  The average sperm density and motility started to decrease significantly by the end of month 2 of medication and gradually reached the infertility levels (< 4 million/mL) in both treated groups. After that the 10 mg group was asked to take the same dose every other day for up to a total observation period of 16-18 months for the maintenance of infertility. Subjects in the 12.5 mg group did not take gossypol any more so as to observe the length of the loading dose required, but in a few, a maintenance dose of 12.5 mg every other day was instituted for a few more months. In both treated groups, none of the spouses was pregnant during the maintenance dose period. Serum levels of potassium, FSH, LH and testosterone were not significantly changed and not a single volunteer complained of myoasthenia. After cessation of drug administration, the semen data returned to pretreatment levels.
  
  
  CONCLUSIONS
  A regimen with 10 or 12.5 mg of gossypol as the daily loading dose and 35 or 43.75 mg as the weekly maintenance dose could induce infertility in male volunteers without developing hypokalemia or irreversibility.
authors.affiliation: Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 200031, China. zpgu@mail.shcnc.ac.cn
authors.forename: Z P
authors.initials: ZP
authors.lastname: Gu
authors.forename: B Y
authors.initials: BY
authors.lastname: Mao
authors.forename: Y X
authors.initials: YX
authors.lastname: Wang
authors.forename: R A
authors.initials: RA
authors.lastname: Zhang
authors.forename: Y Z
authors.initials: YZ
authors.lastname: Tan
authors.forename: Z X
authors.initials: ZX
authors.lastname: Chen
authors.forename: L
authors.initials: L
authors.lastname: Cao
authors.forename: G D
authors.initials: GD
authors.lastname: You
authors.forename: S J
authors.initials: SJ
authors.lastname: Segal
mesh_terms: D003272:Contraceptive Agents, Male / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D005306:Fertilization / Q000187:drug effects; D005640:Follicle Stimulating Hormone / Q000097:blood; D005837:Genitalia, Male / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006072:Gossypol / Q000008:administration & dosage*; D006801:Humans; D007008:Hypokalemia / Q000139:chemically induced / Q000503:physiopathology; D007248:Infertility, Male / Q000139:chemically induced* / Q000378:metabolism; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D011188:Potassium / Q000097:blood; D011247:Pregnancy; D018873:Pregnancy Rate; D013076:Sperm Count; D013081:Sperm Motility / Q000187:drug effects / Q000502:physiology; D013739:Testosterone / Q000097:blood
chemical_list: D003272:Contraceptive Agents, Male; D013739:Testosterone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D006072:Gossypol; D011188:Potassium