Pharmacokinetics of two low-dose levonorgestrel-releasing intrauterine systems and effects on ovulation rate and cervical function: pooled analyses of phase II and III studies

Levonorgestrel intrauterine system 13.5 mg and LNG-IUS 19.5 mg result in alower systemic exposure to LNG, lower incidence of anovulation, and similar progestin impact on the endometrium and cervical function compared with LNG-IUS 20 μg/24 h.