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  1. 1

    Long-acting systemic contraceptives.


    In: Diczfalusy, E., ed. Regulation of human fertility. (Proceedings of the WHO Symposium on Advances in Fertility Regulation, Moscow, USSR, November 16-19, 1976) Copenhagan, Denmark, Scriptor, 1977. p. 323-360

    Long-acting systemic contraceptives inhibit fertility either at a central or peripheral level. In some instances, a mixed reaction is likely to be working: during the 1st portion of the drug's life-span the contraceptive effect is exerted at a hypothalamic central level, whereas later on--when ovulation is restored--the action is on the cervix or uterus. The most important factor holding back utilization of long-acting agents is serious interference with regularity of the menstrual cycle, and delivery systems must be devised with zero-order release rates to improve cycle control and acceptability. Monthly injectables consisting of synthetic progestins alone proved unsuitable for contraception because of frequent and prolonged amenorrhea. Addition of an estrogenic substance helped cycle control, and a dihydroxyprogesterone acetophenide plus estradiol enanthate combination seems most worthy of clinical investigation; so far, 15,000 woman-months of experience have yielded no unwanted pregnancies. Few bleeding pattern irregularities were reported, but premenstrual tension, dysmenorrhea, and libido changes occurred. Reversibility of drug-induced anovulation has been shown by spontaneous ovulation resumption 12-42 weeks after cessation. Tri-monthly injections of Depo Provera resulted in pregnancy rates averaging .5/100 woman-years of use. Biannual injectable and sustained release systems are discussed and data are presented.
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  2. 2

    Factors limiting the development of new contraceptives.

    Bennett JP

    Journal of Reproduction and Fertility. April 1974; 37(2):487-498.

    The rapid decline in the introduction of new drugs in the U.S. can be attributed to the Kefauver-Harris Amendment to the Food and Drug Act of 1962 under which the Food and Drug Administration gets its authority. The regulatory requirements for contraceptive development have greatly curtailed research by pharmaceutical companies in this area. Such aspects as the patent life-span of 17 years when compared to the amount of overall development time to provide the necessary data for the regulatory agencies (for chemical contraceptives about 10 years) reduces the patent life to a point where for industry the commercial return for high research investment is extremely poor. Regulations specifying the kinds of animals used in testing or oral contraceptive (OCs) or the dose levels used in such species have questionable relevance to the human experience. Decisions by the regulatory agencies before marketing which are without appeal, such as the case of chlormadinone acetate, certainly affect the U.S. drug industry. Recent contraceptive development has occurred outside of the U.S. Adverse publicity by lay press increasing fears about OCs has also led to cutbacks in the research by pharmaceutical houses. The introduction of the Contraceptive Development Branch by the United National Institue of Child Health and Human Development in 1969 was a big step forward in directing research towards new approaches to contraception. However, industry has been slow to involve itself in this program because of the restrictive patent laws of the National Institutes of Health. The Expanded Program of the World Health Organization in support of training and of research in new contraceptives is anxious to enlist the support of the pharmaceutical idustry and will operate under more enlightened patent rules. The total estimated funds required to support research in the reproductive field is $500-$600 million over 5 years. It is suggested that industry will become involved again in contraceptive research if government will share the risk of contraceptive development. Our incomplete knowledge of the forms in which contraceptive steroids act at levels in man represent a major obstacle to better steroidal contraceptive development.
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