Plasma levonorgestrel levels and ovarian function during the use of a levonorgestrel-releasing intracervical contraceptive device.
Levonorgestrel, estradiol and progesterone plasma concentrations were measured over four years of use of a 20 micrograms/day levonorgestrel-releasing intracervical device (LNG-ICD). The mean levonorgestrel concentration showed a slight decline, being 142 + 46 (SD) pg/ml in the third month and 81 +/- 22 pg/ml in the 48th month of LNG-ICD use. However, considerable interindividual variation in levonorgestrel plasma levels between study subjects was observed. In 77% of the monitored cycles, ovulation or a luteinized follicle was observed when judged by a plasma progesterone elevation of over 5 ng/ml. Some follicular function was also noted in anovulatory cycles. Inhibition of ovulatory ovarian function is not the mode of contraceptive action of the LNG-ICD.
Ratsula
K
K
Department of Medical Chemistry, University of Helsinki, Finland.
Toivonen
J
J
Lähteenmäki
P
P
Luukkainen
T
T
D000328:Adult; D004958:Estradiol / Q000097:blood; D005260:Female; D006801:Humans; D007436:Intrauterine Devices, Medicated; D016912:Levonorgestrel; D009644:Norgestrel / Q000008:administration & dosage / Q000097:blood* / Q000494:pharmacology; D006080:Ovarian Follicle / Q000187:drug effects; D010053:Ovary / Q000187:drug effects*; D010060:Ovulation / Q000187:drug effects; D011374:Progesterone / Q000097:blood; D013997:Time Factors
D009644:Norgestrel; D011374:Progesterone; D004958:Estradiol; D016912:Levonorgestrel