An investigation of the effectiveness of testosterone implants in combination with the prolactin inhibitor quinagolide in the suppression of spermatogenesis in men.
BACKGROUND
Administration of testosterone inhibits gonadotrophin secretion and spermatogenesis in men but the degree of response is highly variable. This treatment also stimulates prolactin, itself a progonadal hormone in animals. This study investigated whether concomitant suppression of prolactin (PRL) with the non-ergot, dopamine receptor agonist quinagolide (Q), would enhance the efficacy of testosterone in its inhibition of spermatogenesis in healthy eugonadal men.


METHODS
A total of 46 men were randomized to three treatment groups: Group 1, T1200: 1200 mg testosterone implant plus daily oral placebo; Group 2, T1200 + Q: 1200 mg testosterone plus oral Q 75 microg/day; Group 3, T800 + Q: testosterone 800 mg plus oral Q 75 microg/day. After an initial pre-treatment period of 4 weeks, subjects were treated for 24 weeks followed by an 8-week recovery period.


RESULTS
The total numbers of subjects that achieved severe oligospermia (< or =10(6)/ml including azoospermia) from weeks 8-16 were 11/13 (85%), 11/12 (92%), 8/13 (61.5%) in the three groups respectively.


CONCLUSIONS
The results show that inhibition of PRL does not to confer additional efficacy in spermatogenic suppression in men. However, Q did not totally block PRL secretion in the subjects, possibly because testosterone replacement itself stimulated PRL by a direct action on the lactotroph, thus the effectiveness of dual inhibition of gonadotrophin and PRL could not be fully investigated.
Hair
W Morton
WM
MRC Human Reproductive Sciences Unit, The University of Edinburgh, The Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB, UK.
Wu
Frederick C W
FC
Lincoln
Gerald A
GA
D000284:Administration, Oral; D000328:Adult; D000634:Aminoquinolines / Q000008:administration & dosage*; D000728:Androgens / Q000008:administration & dosage*; D018491:Dopamine Agonists / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004343:Drug Implants; D004357:Drug Synergism; D005640:Follicle Stimulating Hormone / Q000037:antagonists & inhibitors / Q000097:blood; D006801:Humans; D007986:Luteinizing Hormone / Q000037:antagonists & inhibitors / Q000097:blood; D008297:Male; D008875:Middle Aged; D011388:Prolactin / Q000037:antagonists & inhibitors*; D013091:Spermatogenesis / Q000187:drug effects*; D013739:Testosterone / Q000008:administration & dosage*; D016896:Treatment Outcome
D000634:Aminoquinolines; D000728:Androgens; D018491:Dopamine Agonists; D004343:Drug Implants; D013739:Testosterone; C046650:quinagolide; D011388:Prolactin; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone