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Levonorgestrel release rates over 5 years with the Liletta® 52-mg intrauterine system

  • Author(s): Creinin, MD
  • Jansen, R
  • Starr, RM
  • Gobburu, J
  • Gopalakrishnan, M
  • Olariu, A
  • et al.

© 2016 Elsevier Inc. Objective To understand the potential duration of action for Liletta®, we conducted this study to estimate levonorgestrel (LNG) release rates over approximately 5½ years of product use. Methods Clinical sites in the U.S. Phase 3 study of Liletta collected the LNG intrauterine systems (IUSs) from women who discontinued the study. We randomly selected samples within 90-day intervals after discontinuation of IUS use through 900 days (approximately 2.5 years) and 180-day intervals for the remaining duration through 5.4 years (1980 days) to evaluate residual LNG content. We also performed an initial LNG content analysis using 10 randomly selected samples from a single lot. We calculated the average ex vivo release rate using the residual LNG content over the duration of the analysis. Results We analyzed 64 samples within 90-day intervals (range 6–10 samples per interval) through 900 days and 36 samples within 180-day intervals (6 samples per interval) for the remaining duration. The initial content analysis averaged 52.0 ± 1.8 mg. We calculated an average initial release rate of 19.5 mcg/day that decreased to 17.0, 14.8, 12.9, 11.3 and 9.8 mcg/day after 1, 2, 3, 4 and 5 years, respectively. The 5-year average release rate is 14.7 mcg/day. Conclusion The estimated initial LNG release rate and gradual decay of the estimated release rate are consistent with the target design and function of the product. The calculated LNG content and release rate curves support the continued evaluation of Liletta as a contraceptive for 5 or more years of use. Implications statement Liletta LNG content and release rates are comparable to published data for another LNG 52-mg IUS. The release rate at 5 years is more than double the published release rate at 3 years with an LNG 13.5-mg IUS, suggesting continued efficacy of Liletta beyond 5 years.

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