Current status of NORPLANT subdermal implants for contraception

Abstract

The NORPLANT subdermal implants merge in a novel manner two medically approved components: levonorgestrel, the drug which is widely used in oral contraceptives throughout the world, and Silastic, polydimethylsiloxane, the silicone rubber through which levonorgestrel diffuses. The NORPLANT system comprises six 3 cm tubes of Silastic filled with levonorgestrel. This system has to date undergone nearly two decades of laboratory research and one decade of clinical trials in a variety of countries and socioeconomic groups. These studies demonstrate that the NORPLANT system is very effective, that continuation rates are high, that there are few side-effects and that there is prompt return to fecundability upon removal of the implants. The Finnish Drug Regulatory Agency (Finland is the country of manufacture) approved the system on 23 November 1983. The expanded manufacture of the NORPLANT system which this decision has stimulated will allow of large-scale public and private sector distribution. As a basis for registration and introduction, additional clinical trials are being conducted in several countries. Meanwhile, studies with two homogeneous rods comprising levonorgestrel and Silastic, each 4 cm in length and covered with Silastic, provide similar release rates and serum levels of levonorgestrel, similar patterns of bleeding and spotting, and similar effects on lipids to those provided by the six 3 cm capsules. These new implants, called NORPLANT-2, which are easier to manufacture, to insert and to remove, may replace the six-capsule NORPLANT system in the future.