Aaron Lazorwitz1, Jeanelle Sheeder2, Stephanie Teal3. 1. University of Colorado Anschutz Medical Campus, Department of Obstetrics and Gynecology, Division of Family Planning, Aurora, CO, United States. Electronic address: aaron.lazorwitz@cuanschutz.edu. 2. University of Colorado Anschutz Medical Campus, Department of Obstetrics and Gynecology, Division of Family Planning, Aurora, CO, United States. Electronic address: Jeanelle.sheeder@cuanschutz.edu. 3. University Hospitals Cleveland Medical Center and Case Western Reserve University, Department of Obstetrics and Gynecology, OH, United States. Electronic address: stephanie.teal@UHhospitals.org.
Abstract
OBJECTIVE: To assess the variability of repeated measurements of serum etonogestrel concentration among contraceptive implant users. STUDY DESIGN: We measured 3 consecutive serum etonogestrel concentrations, drawn weekly, in women using etonogestrel implants for 12 to 36 months. We used a repeated measures test to evaluate differences. RESULTS: Among 20 participants, repeat serum etonogestrel concentrations did not differ from initial measurements (Friedman's test, p = 0.95). Mean serum etonogestrel concentrations had similar 95% confidence intervals at each time point: (134.09, 201.46), (135.08, 237.46), and (132.66, 192.45). CONCLUSION: We confirm that single-time measurements of serum etonogestrel concentration are acceptable pharmacokinetic outcomes for etonogestrel implant studies. IMPLICATIONS: Pharmacokinetic studies of the etonogestrel contraceptive implant assume single-time measurements are stable steady-state estimates based on small studies using older analysis methods. Our repeated measures study using modern liquid-chromatography mass-spectrometry analysis methods provides updated support for single-time pharmacokinetic measurements among etonogestrel implant users.
OBJECTIVE: To assess the variability of repeated measurements of serum etonogestrel concentration among contraceptive implant users. STUDY DESIGN: We measured 3 consecutive serum etonogestrel concentrations, drawn weekly, in women using etonogestrel implants for 12 to 36 months. We used a repeated measures test to evaluate differences. RESULTS: Among 20 participants, repeat serum etonogestrel concentrations did not differ from initial measurements (Friedman's test, p = 0.95). Mean serum etonogestrel concentrations had similar 95% confidence intervals at each time point: (134.09, 201.46), (135.08, 237.46), and (132.66, 192.45). CONCLUSION: We confirm that single-time measurements of serum etonogestrel concentration are acceptable pharmacokinetic outcomes for etonogestrel implant studies. IMPLICATIONS: Pharmacokinetic studies of the etonogestrel contraceptive implant assume single-time measurements are stable steady-state estimates based on small studies using older analysis methods. Our repeated measures study using modern liquid-chromatography mass-spectrometry analysis methods provides updated support for single-time pharmacokinetic measurements among etonogestrel implant users.
Authors: Catherine A Chappell; Mohammed Lamorde; Shadia Nakalema; Beatrice A Chen; Hope Mackline; Sharon A Riddler; Susan E Cohn; Kristin M Darin; Sharon L Achilles; Kimberly K Scarsi Journal: AIDS Date: 2017-09-10 Impact factor: 4.177