Pharmacokinetics and ovarian suppression during use of a contraceptive vaginal ring in normal-weight and obese women.
OBJECTIVE
Many observational studies indicate higher oral contraceptive failure among obese women, but most clinical trials and physiologic studies do not support these differences. Limited data indicate higher failure rates among obese contraceptive patch users. Data regarding contraceptive vaginal ring performance in obese women are needed.


METHODS
Twenty normal weight (body mass index [BMI] 19.0-24.9; median, 21.65) and 20 obese (BMI 30.0-39.9; median, 33.7) women enrolled in a prospective study of ethinyl estradiol (EE(2)) and etonorgestrel pharmacokinetics and of ovarian follicle development, endometrial thickness, and bleeding patterns, all measured biweekly during the second cycle of contraceptive vaginal ring use.


RESULTS
Thirty-seven women completed follow-up. Mean day 0-21 EE(2) concentrations were lower among obese vs normal weight women (15.0 vs 22.0 pg/mL, respectively, P = .004), whereas etonorgestrel concentrations were similar (1138 vs 1256 pg/mL, respectively, P = .39). Follicular development was minimal in both groups, with only 5 women achieving a maximum follicle diameter >13 mm at any time during 3 weeks follow-up (3 normal weight and 2 obese women); these women had serum progesterone levels <1.0. Obese women reported more bleeding or spotting than normal weight women (3.6 vs 1.4 days, respectively, P = .01).


CONCLUSIONS
Although obese women had lower EE(2) levels during contraceptive vaginal ring use, they had excellent suppression of ovarian follicle development, similar to normal weight women. This predicts that contraceptive vaginal ring effectiveness will be similar in women with a BMI up to 39.9. The lower serum EE(2) levels in the obese women may explain the greater reported bleeding or spotting days.
Department of Obstetrics and Gynecology, College of Physicians and Surgeons, Columbia University, New York, NY, USA.
Carolyn L
CL
Westhoff
Anupama H
AH
Torgal
Elizabeth Rose
ER
Mayeda
Kelsey
K
Petrie
Tiffany
T
Thomas
Monica
M
Dragoman
Serge
S
Cremers
D000293:Adolescent; D000328:Adult; D003271:Contraceptive Agents, Female / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology; D003274:Contraceptive Devices, Female; D017135:Desogestrel / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology; D004717:Endometrium / Q000187:drug effects; D004967:Estrogens / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology; D004997:Ethinyl Estradiol / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008598:Menstruation / Q000187:drug effects; D009765:Obesity / Q000097:blood; D006080:Ovarian Follicle / Q000187:drug effects; D011446:Prospective Studies; D055815:Young Adult
D003271:Contraceptive Agents, Female; D004967:Estrogens; C044815:etonogestrel; D004997:Ethinyl Estradiol; D017135:Desogestrel