A proof-of Concept, Randomized 3-month Study to Evaluate the Effects of Three Contraceptive Intrauterine Systems Delivering Copper and a Daily Dose of 5, 20 or 40 μg of Ulipristal Acetate (UPA)

The UPA doses to be tested in this new IUS, 5, 20 or 40 μg per day, are not expected to suppress ovulation, however they should prevent endometrial growth resulting in endometrial atrophy, minimal bleeding, or even amenorrhea. It is anticipated that with low UPA doses, women will continue to ovulate and secrete progesterone (P) during the secretory phase of the menstrual cycle. As a result, PRM associated endometrial changes (PAECs) that have been described in previous UPA studies when ovulation was suppressed and associated with amenorrhea should not occur and endometria should retain normalcy. These expectations are based on our findings from a previous study in which the UPA doses tested were insufficient to block ovulation and participants maintained P secretion with normal endometria (protocol 349). Further evidence regarding the benefit of using low doses of UPA in a copper IUS stems from a small rhesus macaque proof of principle study that included an UPA-IUS delivering 40 or 60 μg/d of UPA, and fixed doses of E2 and cyclic P delivered via implants over 3 cycles.24 Indices of endometrial proliferation were significantly reduced in 3 out of 5 animals in that study; the endometria were atrophied with some glandular cysts, and typical PAECs were limited. Glands were generally small and tubular, however, in some animals they were large and dilated; resembling cysts with minimal evidence of proliferative activity.24 No bleeding was observed in the treated monkeys during progesterone withdrawal over the 3 cycles.