It advises using a backup. Since last October, Wyeth has distributed nearly 22,000 kits. Each contains six flexible plastic capsules that, when inserted into a woman's arm, prevent pregnancy by continuously releasing the synthetic hormone levonorgestrel. The capsules are supposed to be effective for five years. During routine quality-control testing, Wyeth discovered that the capsules were releasing an unexpectedly low amount of hormone.
Norplant failures are rare, even rarer than with sterilization, studies show.
For every 10,000 women who use Norplant for five years, fewer than five will become pregnant. 5 million women worldwide have used the method. Still, Wyeth has been besieged by Norplant lawsuits, particularly in the United States, where the product was approved in 1990. In the Philadelphia area, the impact of Wyeth's warning may be small, judging by family-planning clinics' experience. Only 60 women have received the potentially ineffective implants at clinics funded by the Family Planning Council of Southeastern Pennsylvania, said Dorothy Mann, executive director.