Looking into the future.

Abstract

Present day methods of contraception including oral contraceptives (OCs), barrier methods, and IUDs, are likely to be in use in the foreseeable future, and utilization of hormonal methods will probably increase. Drugs are developed in a series of stages beginning with synthesis of new chemical entities in the laboratory, trials in animals, and Phase I clinical trials in humans where 10-20 volunteers receive the drug usually for less than 2 weeks. If no serious side effects are detected, Phase II clinical trials usually involving 50-100 subjects can be undertaken for several months. Phase III trials may include 1000 or more users and proceed for more than 1 year. Only 1 in 1000 or fewer new drugs ever reach the market. Contraceptives receive closer scrutiny than other drugs, with the US Food and Drug Administration requiring 7-year dog and 10-year monkey studies before drugs are approved for marketing. Contraceptive devices usually receive more rapid approval. Introduction of a fundamentally new contraceptive in the US market can cost up to $50 million and require 10 or more years of research. 1 recent advance in contraception is the availability of effective postcoital contraception in the form of high dose combination OCs taken within 72 hours of unprotected intercourse or insertion of an IUD. New, longer lasting IUDs have been developed and new ways of delivering contraceptive hormones, such as microencapsulation, are in development. The 1970s saw expanded use of symptothermal and mucus detection methods of determining fertile periods, and new developments may occur in the next 5 years. Hypothalamic releasing hormones may become available as contraceptives in the late 1980s or 1990s; a few analogs have reached Phase I or II clinical trials. Thyroid releasing hormone is under study as an experimental contraceptive to suppress ovulation; its use to turn lactation into a totally reliable contraceptive method would be a major advance for the developing world. Successful clinical trials have been conducted of self-administration of prostaglandins in the home to induce delayed menstruation, but such methods have provoked antagonism. The World Health Organization is conducting a program that attempts to identify new clinical entities extracted from plants that might prove useful in contraception following chemical modification. Gossypol is a well known recent example of discovery of a plant contraceptive. Development of a successful contraceptive vaccine could revolutionize contraceptive practice in the 1990s. Development of antibodies against the zona pellucida is 1 promising approach. Safety studies should continue after approval of new drugs. Despite the need for improved contraception, investment in research is declining.