Neuroendocrine mechanism of anovulation in users of contraceptive subdermal implant of nomegestrol acetate (Uniplant).
OBJECTIVE
To evaluate a nomegestrol acetate subdermal contraceptive implant's (Uniplant; Thermex, Monaco) effect on the hypothalamus-pituitary-ovarian axis.


METHODS
A prospective clinical trial.


METHODS
San Borja-Arriarán Clinical Hospital, University of Chile, School of Medicine.


METHODS
Normally cycling healthy women.


METHODS
Insertion of Uniplant.


METHODS
Luteinizing hormone pulse and endocrine profiles were assessed before, 48 hours after insertion, and after prolonged use of the implant.


RESULTS
Anovulation was noted in 100% of users in the first month. Seventy percent of subjects demonstrated follicular development with the absence of ovulation and an endocrine profile similar to the follicular phase: (LH pulse/8 hours 6.85 +/- 0.67, LH amplitude 3.54 +/- 0.65 mIU/mL (conversion factor to SI unit, 1.00), and E2 193 +/- 29.4 pg/mL (conversion factor to SI unit, 3.67), whereas 30% demonstrated no follicular activity with an endocrine profile similar to the luteal phase: (LH pulse/8 hours; 3.66 +/- 0.66, LH amplitude 5.76 +/- 1.73 mIU/mL, and E2 67.5 +/- 4 pg/mL. Clinical characteristics, serum gonadotropin concentration, and LH pulse characteristics failed to predict which subjects would initiate or remain devoid of follicular activity.


CONCLUSIONS
Uniplant results in anovulation via two mechanisms: hypothalamic suppression in subjects who lack follicular development, and likely suppression of the pituitary LH surge in subjects who initiate follicular activity.
Barnhart
K
K
University of Chile, School of Medicine, San Borja-Arriarán Clinical Hospital, Santiago, Chile.
Devoto
L
L
Pommer
R
R
Sir-Pettermann
T
T
Robinovic
J
J
Coutinho
E
E
D000328:Adult; D004343:Drug Implants; D004702:Endocrine Glands / Q000502:physiology; D004958:Estradiol / Q000097:blood; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D006801:Humans; D007986:Luteinizing Hormone / Q000097:blood; D008535:Megestrol; D009490:Neurosecretory Systems / Q000502:physiology*; D009649:Norpregnadienes / Q000008:administration & dosage* / Q000494:pharmacology; D006080:Ovarian Follicle / Q000502:physiology; D010060:Ovulation / Q000187:drug effects*; D013997:Time Factors
D004343:Drug Implants; D009649:Norpregnadienes; D004958:Estradiol; C038501:nomegestrol acetate; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D008535:Megestrol