Aaron Lazorwitz1, Rebecca Seale2, Anne Davis3, Maryam Guiahi2. 1. University of Colorado Anschutz Medical Campus, Department of Obstetrics and Gynecology, Division of Family Planning, United States. Electronic address: Aaron.lazorwitz@cuanschutz.edu. 2. University of Colorado Anschutz Medical Campus, Department of Obstetrics and Gynecology, Division of Family Planning, United States. 3. Columbia University Irving Medical Center, Department of Obstetrics and Gynecology, Division of Family Planning, United States.
Abstract
OBJECTIVE: To explore the pharmacokinetic interaction between isotretinoin, a cytochrome P-450 (CYP) inducer and potent teratogen, and the etonogestrel contraceptive implant. STUDY DESIGN: We enrolled healthy reproductive-age women initiating isotretinoin and using an etonogestrel implant. We compared serum etonogestrel concentrations at baseline and after four and nine weeks of isotretinoin co-administration using a validated assay. RESULTS: Among eight implant users, all serum etonogestrel concentrations remained >90 pg/mL during isotretinoin co-administration with no significant changes from baseline (p = 0.25, Friedman's test). CONCLUSION: In this exploratory study, we found that isotretinoin did not cause serum etonogestrel concentrations to fall below the threshold for ovulatory suppression (<90 pg/mL) among implant users. IMPLICATIONS: Reproductive-age women treated with isotretinoin require reliable contraception to prevent pregnancies impacted by teratogenic-effects. This small study demonstrates that contraceptive implant users maintained serum etonogestrel concentrations above the threshold for consistent ovulatory suppression during isotretinoin co-administration. The contraceptive implant remains an appropriate option for patients considering isotretinoin therapy.
OBJECTIVE: To explore the pharmacokinetic interaction between isotretinoin, a cytochrome P-450 (CYP) inducer and potent teratogen, and the etonogestrel contraceptive implant. STUDY DESIGN: We enrolled healthy reproductive-age women initiating isotretinoin and using an etonogestrel implant. We compared serum etonogestrel concentrations at baseline and after four and nine weeks of isotretinoin co-administration using a validated assay. RESULTS: Among eight implant users, all serum etonogestrel concentrations remained >90 pg/mL during isotretinoin co-administration with no significant changes from baseline (p = 0.25, Friedman's test). CONCLUSION: In this exploratory study, we found that isotretinoin did not cause serum etonogestrel concentrations to fall below the threshold for ovulatory suppression (<90 pg/mL) among implant users. IMPLICATIONS: Reproductive-age women treated with isotretinoin require reliable contraception to prevent pregnancies impacted by teratogenic-effects. This small study demonstrates that contraceptive implant users maintained serum etonogestrel concentrations above the threshold for consistent ovulatory suppression during isotretinoin co-administration. The contraceptive implant remains an appropriate option for patients considering isotretinoin therapy.
Authors: Craig W Hendrix; Kimberley A Jackson; Elizabeth Whitmore; Anita Guidos; Ryan Kretzer; Catherine M Liss; Leena P Shah; Ko-Chin Khoo; John McLane; Carol Braun Trapnell Journal: Clin Pharmacol Ther Date: 2004-05 Impact factor: 6.875