Intrauterine device for governing the reproductive process

Claim 1

An intrauterine device for the administration of an antifertility agent at a controlled rate for a prolonged period of at least one month, said device consisting essentially of; a. a reservoir comprising dissolved antifertility agent and undissolved replacement antifertility agent selected from the group consisting of progestational and estrogenic steroids in a liquid core material permeable to the passage of agent, the replacement agent present in an amount sufficient to maintain the dissolved agent in an amount substantially equal to the amount of dissolved agent originally present in the core during said prolonged period, said reservoir surrounded by; b. a shaped wall having two free closed ends with one end extended around the other end and receded from it with a radius of about one centimeter to two and one-half centimeters to define the device adapted for insertion and placement within a uterus, said wall formed of a release rate controlling permeable to the passage of agent with the permeability of the wall to the agent lower than the permeability of the core to the agent; and, c. said device when placed in the uterus releasing dissolved agent from the reservoir in a contraceptively effective amount by metered passage through the wall, the agent so released being replaced by the continuous dissolving of replacement agent in the core material.