A study comparing the ovarian effects of levonorgestrel and desogestrel given orally and by vaginal ring

SummarySummaryTo compare the effects of two progestagens delivered in two different ways, 40 healthy ovulating volunteers were allocated to four groups. Study design included a control cycle, a study cycle and a recovery cycle. On day two of the menstrual cycle, group 1 used a vaginal ring releasing 20 μg/24 hours of levonorgestrel for 21 days, group 2 and 3 took 30 μg levonorgestrel and 60 μg desogestrel tablets respectively for 21 days. Group 4 used a 3-keto-desogestrel vaginal ring releasing 30 μg/24 hours. The steady state plasma levels with the keto-desogestrel ring did not differ from the trough levels of the 60 μg desogestrel tablets. The release rate from the levonorgestrel containing ring was in a similar relationship to the release rate from the levonorgestrel tablet. Ovulation was inhibited in 4/10 in the levonorgestrel ring group, 8/10 with the levonorgestrel tablet group; no ovulation was seen with the keto-desogestrel tablet or the desogestrel ring. All treatments were associated with persistent follicle formation, but no difference between the groups was found in this respect. A new classification of ovarian reaction including ultrasound data, reflecting the above findings, is proposed.