Sites: 1 Phase: 1 Main objective:To establish the minimum effective dose of progesterone microspheres suspension, which administered by weekly intramuscular injection, will be able to induce transformation from a proliferative endometrium to a secretory endometrium.~Secondary objectives:~To determine and compare the steady-state pharmacokinetic profile of investigational products.~To evaluate safety profile of investigational products in the study subjects.~To evaluate local tolerability of investigational products in the study subjects.~Study design:Randomized, controlled, open-label, parallel, dose-response clinical trial.~Investigational products:~Progesterone microspheres intramuscular injectable suspension 50 mg~Progesterone microspheres intramuscular injectable suspension 100 mg~Progesterone microspheres intramuscular injectable suspension 200 mg~Progesterone microspheres intramuscular injectable suspension 300 mg Study subjects: 48 healthy postmenopausal women, 45 - 60 years. Brief description: After written informed consent, 48 eligible women will receive pretreatment with oral estradiol valerate, then, 14 days later, those with adequate endometrial thickness evaluated through ultrasound will be randomized to study treatments (one IM injection each 7 days, for a total of 7 doses). 10 days after the first progesterone dose, an endometrial biopsy will be obtained. Blood samples will be obtained for pharmacokinetic study.
Phase: I pharmacokinetic - pharmacodynamic (PK-PD) study. Main objective: To establish the minimum effective dose of progesterone microspheres suspension, which administered by weekly intramuscular injection, will be able to induce transformation from a proliferative endometrium to a secretory endometrium.~Study design: Randomized, controlled, open-label, parallel, dose-response clinical trial.~Sites: 1 Subjects: 48 postmenopausal women.