The contraceptive ring (CR) is a method for delivering steroids by vaginal route for fertility control. The project describes our plans to study a CR containing a combination of norethindrone acetate (NET Ac: 13beta-methyl- 17alpha-ethynyl-17beta-acetoxy-19-norandrosten-4-en-3-one) and ethynylestradiol (EE: 17alpha-ethynyl-1,3,5,(10)-estratriene-3,17beta- diol). This device could be an important addition to modern forms of contraception. It provides a special advantage to women who wish to have the initiation and termination of a contraceptive method under their own control. In previous studies, a wide range of dose combinations were tested in a CR that provided protection from pregnancy for three months. To date, rings that deliver a dose of NET Ac/EE of 1 mg/20 mug inhibit ovulation and control bleeding well. These Phase 2 studies will be completed to establish the lowest dose of EE necessary in combination with 1 mg of NET Ac to effectively control bleeding patterns, inhibit ovulation, and produce minimal effects on lipid patterns. The CRs for these studies will be made in the laboratories of the Population Council. The Population Council has established a relationship with a commercial partner, and will transfer technology for manufacture of CRs that deliver the agreed doses. The commercially-manufactured CRs will be tested both in vivo and in a Phase 2 study to confirm that they perform as well as the Population Council's handmade CRs. A study will be conducted on the final NET Ac/EE dosage selected to investigate variations in the CR insertion schedule on the first day of each cycle to minimize side effects. This same study will also give information on the acceptability of CRs. Stability studies will be performed on the manufactured CRs to establish the product's shelf life. Finally, a Phase 3 study will be conducted on the manufactured CRs to determine acceptability, effectiveness, control of menstrual bleeding, and any possible side effects. The goal is to apply for a New Drug Application and register the CR in the United States.