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release and clinical performance identical to that of the six-rod presentation but has a 3-year term of efficacy. The two-rod system was actually to have been the first implant launched on the U.S. market but, while trials were under way, the supplier ceased manufacture of the elastomer used in the core of the Norplant-2 implant and a change of plans was required.5
Definitions of advantages and disadvantages of any contraceptive method are partly subjective, dependent as they are on individual physiology and context but, in general, the inherent advantages and disadvantages of progestin implants as a contraceptive category are as follows:
Advantages: extremely high efficacy; estrogen-free protection; low and stable blood level maintenance; freedom from need for daily compliance; rapid return to previous fertility; no interference with coitus; no manipulation of genital area; easy palpation; and long duration of action.
Disadvantages: requirement for minor surgical procedures for insertion and removal; lack of dosage titration; bleeding irregularities (prolonged bleeding, spotting, or amenorrhea); mood alterations (e.g., depression); visibility of implant; possible local scar formation; and, as with all methods other than condoms, no protection from sexually transmitted infection.
The intersectoral research and development process that brought Norplant onto the world market began in the mid-1960s, with articulation by the Population Council of the general concept and objectives of implant technologies. In December 1990, after 25 years of development, FDA approval was granted. The process involved three major players and total costs of over $110 million:
Population Council: research, $23.5 million; introduction into developing countries, $16 million
Leiras Oy: development of manufacturing procedures, an estimated $23 million
Wyeth-Ayerst: introduction into private sector, an estimated $50 million.6
Preparation for regulatory approval and eventual introduction of Norplant began in the early 1980s. The Population Council devised its introduction strategy in 1982 and began clinical trials and, later, preintroduction studies, in countries ranging from minimally to highly industrialized. It also licensed Norplant to Leiras Oy, a pharmaceutical company in Finland, the first country to approve the method. By 1988, over 55,000 women had had experience with Norplant through trials and studies in 41 countries (see Table B-1). These women were followed during the subsequent decade through over 70 user-acceptability studies conducted by the Council and other agencies in 20 countries,7 which investigated method use and continuation, quality of care and counseling services, provider training, provider-client communication, adopter follow-up, access to the product and its removal, and overall satisfaction.