Researchers conducted this study to compare systemic exposure to levonorgestrel (LNG) released from commercially available IUSs, a subdermal implant, and oral contraceptives.
An integrated popPK analysis of data from over 3400 individuals in ten clinical studies with six different LNG-releasing contraceptives was conducted to generate a popPK model. LNG release rates and total and unbound serum/plasma LNG concentrations with LARCs were estimated over the indicated period of use; Cmax and Cav serum LNG concentrations were assessed at a steady state for oral contraceptives. The influence of body weight on LNG PK was also investigated.
Serum LNG concentration with LARCs increased with increasing daily LNG release rate, being lowest with LNG-IUS 8, higher with LNG-IUS 12 and LNG-IUS 20, and highest with the subdermal implant. Compared with early serum LNG concentrations with LNG-IUS 20, Cav and Cmax were 1.7- and 4.5-fold higher with POP, and 8.6- and 18-fold higher with COC. Total LNG bioavailability was >97% for the LNG-IUSs and 66–80% with other contraceptives. Serum/plasma LNG concentrations decreased with increasing body weight.
The study concluded that COC had the highest and LNG-IUSs the lowest systemic exposure to LNG among the contraceptives examined. Systemic LNG concentration was inversely correlated to body weight.
Reference: https://www.tandfonline.com/doi/full/10.1080/13625187.2020.1815008
