Single-dose administration of the gonadotropin-releasing hormone antagonist, Nal-Lys (antide) to healthy men.
OBJECTIVE
To evaluate the ability the Nal-Lys GnRH antagonist ([N-Ac-Nal (2)1, 4ClDPhe2, D3Pal3, Lys (Nic)5, D-Lys(Nic)6, Lys (iPr)8, D-Ala10] to suppress gonadotropins and T in humans and to assess its duration of action and its local effects.


METHODS
Placebo-controlled clinical study.


METHODS
A university community.


METHODS
Seven normal male volunteers.


METHODS
We administered single injections of Nal-Lys (0, 10, 25, and 50 micrograms/kg body weight). Blood samples were collected before and at frequent time intervals after injection.


RESULTS
Nal-Lys caused only minor local effects. At the higher doses (25 and 50 micrograms/kg), serum LH and T levels were suppressed to 50% to 70% of baseline; serum FSH levels were suppressed to 70% to 80% of baseline, and levels of all three hormones returned to basal values within 24 hours after injection.


CONCLUSIONS
In humans, Nal-Lys has similar potency and duration of action to other antagonists and produces fewer local side effects. However, the utility of Nal-Lys is limited by formulation difficulties; current efforts are directed at improving the formulation in order to explore the potential clinical uses of this peptide.
Bagatell
C J
CJ
VA Medical Center, Seattle, Washington 98108.
Conn
P M
PM
Bremner
W J
WJ
D000328:Adult; D005640:Follicle Stimulating Hormone / Q000097:blood; D007987:Gonadotropin-Releasing Hormone / Q000037:antagonists & inhibitors; D006801:Humans; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D009842:Oligopeptides / Q000008:administration & dosage* / Q000097:blood / Q000494:pharmacology; D012016:Reference Values; D013739:Testosterone / Q000097:blood
D009842:Oligopeptides; D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; C057022:iturelix