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ENTRE NOUS. 1991 Dec; (19):15.About 8 million women use the long acting injectable contraceptive depot-medroxy-progesterone acetate (DMPA) and norethisterone enanthate (NET-EN). These progesterone only injectables are not dependent on sexual activity and are easy to administer. Yet they are not always well accepted since they can interfere with menstrual bleeding and often induce amenorrhea. Researchers find that adding estrogen to DMPA and NET-EN treats these irregularities. They must use esters with limited action to protect the endometrium from constant estrogens, however, which requires monthly injections. Thus bleeding occurs once a month just like the normal menstrual cycle. Clinical trials in China of Injectable No. 1 (250 mg 17-alpha-hydroxyprogesterone caproate and 5 mg estradiol valerate) show that it has few side effects and is acceptable. Other trials in China are evaluating monthly injectables with NET-EN or megestrol acetate. Numerous developing countries often as WHO's Special Programme of Research in Human Reproduction for effective, safe, and fully studied monthly injectables. WHO operates under a 2 part strategy: optimum improvement of HPR 102 (50 m NET-EN and 5 mg estradiol valerate) and Cyclofem (25 mg DMPA and 5 mg estradiol cypionate) resulting in a reduction of the dose of at least 1 of the hormones and results of a study of the efficacy and side effects of these 2 injectables. It hopes the study provides the impetus to introduce them into national family planning programs. It demonstrates that they are indeed efficacious, effect fewer changes in the menstrual cycle than the progesterone only injectables, and are well accepted, even though women must go to a clinic every 27-33 days for an injection. Other studies are determining their effects on lipid and glucose metabolism, coagulation, and fibrinolysis. They are also looking at the time needed for ovulation to return. 1 study shows that menstruation returned in all women by the 3rd cycle.
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. 323-360Long-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.
In: Diczfalusy, E. and Borel, U., eds. Control of human fertility. Proceedings of the Fifteenth Nobel Symposium, Sodergarn, Lidingo, Sweden, May 27-29, 1970. New York, Wiley, 1971. 39-51.A drug delivery system providing for a controlled release of progestogen and affecting ovulation and steroidogenesis minimally would deal effectively with some of the problems associated with contraception. 2 systems being developed which fit these criteria are the primary topics of discourse in this article. In 1 system an implant consists of a polymer membrane of polydimethylsiloxane (PDS) and contains the progestogen in crystalline form. Major problems with the PDS implants include a lack of intraindividual constance of release and interindividual variation in the slope of the decay in release. In the second system the implant consists of a lipid-steroid membrane containing a steroid. In this implant the concentration of the steroid in the membrane and the nature of the lipid phase may be important in determining the pattern of release. In vivo metabolic studies with lipid-steroid pellets are limited, but the patterns of output may be similar to those seen with PDS implants. Because of rate problems, a shorter regime slow-release implant seems more feasible than a longer lasting system. Surgical difficulties associated with the implantation and removal of the PDS implant make the choice of a lipid-steroid micropellet preparation more feasible for a short-term regimen. The discussion, following the main body of the article, focuses primarily on problems associated with implants.