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Geneva, Switzerland, WHO, Department of Reproductive Health and Research, . 3 p.The development of new and improved methods of contraception for both women and men is a key component of the strategy to improve the quality of family planning programmes. Family planning clients are often restricted by the choice of methods offered to them, or are deterred from using contraception due to the side effects related to use of available methods. (excerpt)
In: Annual technical report, 1992, [of the] World Health Organization [WHO]. Special Programme of Research, Development and Research Training in Human Reproduction. Geneva, Switzerland, WHO, 1993. 23-36. (WHO/HRP/ATR/92/93)This 1992 annual report of the Task Force on Long-acting Systemic Agents for Fertility Regulation of the World Health Organization's Special Programme of Research, Development, and Research Training in Human Reproduction states that the main objectives of the Task Force are the development of new compounds and/or delivery systems which are superior to existing methods and which are easily delivered by family planning programs. Projects completed in 1992 include a major Phase III clinical trial comparing the once-a-month injectables (which induce regular monthly estrogen-withdrawal bleeding) Mesigyna and Cyclofem in 12 centers in Egypt, a Phase III clinical trial comparing these agents with the Chinese Injectable No. 1 in China, a multicenter study of the effects of Mesigyna and Cyclofem on lipid metabolism and on coagulation and fibrinolysis, and a study in Mexico of the return of fertility after discontinuation of the injectables. Also completed in 1992 were two studies on the pharmacokinetics of the injectables depot medroxyprogesterone acetate and norethisterone enanthate (NET) and a multicenter Phase II study comparing levonorgestrel butanoate (HRP002) to NET. Because of the favorable results of this last study, pharmacokinetic studies of an improved formulation of HRP002 are ongoing. A Phase III clinical trial of the vaginal rings in the UK revealed that a number of users developed vaginal lesions. This development will be given priority in further tests. Other ongoing and planned activities of the Task Force revolve around attempts to develop hormonal postpartum contraception which prevents exposure of breast-fed infants to synthetic steroids and attempts to deal with the problem of unpredictable endometrial bleeding associated with progestogen-only methods.
The WHO Special Programme of Research, Development and Research Training in Human Reproduction and its Task Force on Vaccines for Fertility Regulation.
In: Reproductive immunology 1986, [edited by] D.A. Clark and B.A. Croy. Amsterdam, Netherlands, Elsevier Science Publishers, 1986. 154-61.In the early 1970s the WHO's Special Program of Research, Development and Research Training in Human Reproduction was formed. Its objectives were to study new methods of fertility regulation and infertility, to disseminate information, and to aid research in developing countries. 9 task forces conduct research in sundry areas. Highly effective, long- acting, injectable contraceptives are used by 3.5 million women worldwide, but these agents produce menstrual bleeding disorders and amenorrhea. Other research subjects are biodegradable contraceptive, implants, which deliver constraint amounts of a drug during a 2-year period; a levonorgestrel-releasing vaginal ring, delivering a tiny amount of progestogen; new post-coital drugs effective during a first 5 weeks post-ovulation; sperm antigens, ovum antigens, and hormonal and non-hormonal antigens of the trophoblast and early placenta. Hyaluronidase and acrosomal protease, which are involved in the spermatozoa's penetration of the cumulus cells and zona pellucida of the ovum, respectively, can elicit high antibody responses. Encouraging findings were obtained with the sperm-specific isozyme, lactic dehydrogenase C-4. Ovum antigens directed at zona pellucida (ZP) demonstrated that antibodies can prevent sperm attachment. Immunization of female baboons with whole porcine ZP produced an antifertility effect. Two hormonal placental antigens, human placental lactogen, and human chorionic gonadotrophin (hCG) were also studied to develop an anti-hCG vaccine consisting of a synthetic peptide conjugated to diphtheria toxoid and mixed with a muranyl dipeptide adjuvant. Another line of inquiry was to determine if an anti-sperm immune response restricted to the lumen of the female genital tract could be elicited by application of acrosin and hyaluronidase to the cervix. The antibody profiles of the are of individuals with unexplained infertility were compared with those of fertile controls to identify certain immune responses that were consistently linked to infertility.
[Contraception via a vaginal hormonal ring] Kontratseptsiia posredstvom vlagalishten khormonalen prusten.
AKUSHERSTVO I GINEKOLOGIIA. 1991; 30(1):49-52.Research on the hormonal vaginal ring began in the US in 1973. Its prototype with a diameter of 55 mm releasing in even doses small amounts of hormone was introduced 17 years later. Its high effectiveness with a failure rate of 3-4 pregnancies/100 woman use years is similar to that of most IUDs. The first type contains a combination of estrogen-gestagen consisting of levonorgestrel and 17-beat-estradiol as in oral preparations. It has to be used from the beginning of the menstrual cycle for 3 weeks and removed for 1 week. The second one, devised by a special program of WHO, contains gestagen only in the form of levonorgestrel (LNG) releasing 20-25 mcg of LNG daily. The third type contains progesterone only which is suitable for use by lactating women, as the progesterone eventually absorbed in the maternal system does not pose any risk to the nursing child. At present its effectiveness is being tested, and then its practical application will be examined. The introduction of the prototype was delayed by 2 years when initial investigations showed that the substance used for polymerization of the plastic used for the vaginal ring was carcinogenic, however, this was refuted in subsequent investigations. The vaginal ring is already sold regularly in Great Britain and in some western European countries. This new method allows doctors to provide an alternative contraceptive in addition to the existing ones.
Progesterone-releasing vaginal rings for use in postpartum contraception. I. In vitro release rates of progesterone from core-loaded rings.
CONTRACEPTION. 1992 Apr; 45(4):329-41.Chemists from London, England and a chemist from WHO in Geneva, Switzerland compared release rates of progesterone from vaginal rings with cores of different diameters (4, 5, 6, 6.7, and 7.24 mm). The manufacturer loaded each core with 25% w/w progesterone. The technique used to dissolve the progesterone from the silicone rubber core consisted of placing the rings in continuously flowing baths of isotonic saline at 37 degrees Celsius. The learned that a membrane diffusion controlled process, modified by the development of a gradually increasing zone of depletion at the core surface, did indeed release the progesterone. The used the UV absorption method to measure the amount of progesterone released in 24 hour periods for as much as 128 days. The vaginal ring with the 6 mm core released 3.6-5.5 mg progesterone/day in a 90 day period. The daily range of maximum and minimum values for each set of rings demonstrated good reproducibility. Progesterone release was inversely related to diffusion distance (between core surface and ring surface) for each day. Since, in their clinical trials in postpartum women, WHO wanted to use vaginal rings which initially released 5 mg progesterone/day and declines by about 0.5 mg/month under conditions of membrane limited diffusion as the depletion zone grew thicker, the study showed that the rings with a 6 mm core met the criteria. The chemists found that these rings and 4 sterile batches of these rings have highly consistent and reproducible rates in vitro drug delivery. They also compared the vaginal rings with a 6 mm core with rings with at homogeneous dispersion of progesterone throughout the polymer. The homogenous rings 1st released much progesterone then fell quickly from 10->20 mg/day during the 1st week to a gradual release of about 6 mg/day during the end of the 90 days.
International Family Planning Perspectives. 1992 Jun; 18(2):75-7.The main points of a study from the WHO Special Program of Research, Development and Research and Training in Human Reproduction on menstrual bleeding patterns and contraceptive use are presented. 1875 users of oral contraceptives, 1822 users of monthly injectables, 546 users of vaginal rings, and 1109 depot-medroxyprogesterone acetate (DMPA) users kept diaries of full bleeding and days of spotting during the 1st year a method was started. This information was compared with data from the 1930s and 1960s on bleeding patterns among nonusers of contraceptive methods. Monthly data were excluded in which pregnancy occurred of following a pregnancy, and when there were menstrual disorders or gynecological surgery. Data were then limited to women aged 18-34 years which left 3893 woman years of menstrual cycles. The results revealed that women who used hormonal contraceptives such as the vaginal ring or monthly injectables tended to have shorter periods of menstrual bleeding and more regular predictable periods than women on longterm injectables. Most women have variable bleeding patterns during the year, even when not using hormonal methods. Nonusers, pill users, and vaginal ring users had a median of just more than 3 bleeding or spotting day episodes during a 90-day period vs. 3 days among injectable users and <2 days for DMPA users. However, when the average duration of bleeding or spotting episodes was examined, the median was 4 days for pill users, 5 days for vaginal ring users, and 6 days for DMPA users. Menstrual cycle average length was lowest at 26 days for vaginal ring users, 28 days for nonusers, 29 days for injectable users, and 36 days for DMPA users. The median value for difference between the longest and the shortest cycle within 12 months was around 10 days for nonusers and pill users and 24 days for injectable or vaginal ring users vs. 55 days for DMPA users. The median for the longest episode of bleeding or spotting was 5 days for pill users, 7 days among nonusers, monthly injectable users, or vaginal ring users, and 12 days among DMPA users, of which 25% bled for at least 21 days and 1 in 29 bled for 55 days or more. The shortest bleeding-free intervals was the median for vaginal ring users at 21 days, and longest for DMPA users at 27 days. Other methods were similar to the intervals for the vaginal ring. 25% of DMPA users had a minimum bleeding-free interval of only 2 days, and 25% had an interval of at least 20 days. The myth is debunked that normal women have normal and regular cycles of 25-35 days.
Acta Obstetricia et Gynecologica Scandinavica. 1991; 70(4-5):259-62.On its 20th anniversary, the Special Programme of Research, Development and Research Training in Human Reproduction, commonly known as the Human Reproduction Program (HRP) is featured in this editorial with a summary of its objectives and 2 main functions. HRP is a program of international technical cooperation to promote reproduction research, particularly in developing countries. It is funded by WHO, the UN Development Programme, the UN Population Fund and the World Bank, with major support from the Scandinavian countries. Its 2 operations are research and development, and strengthening human and material resources for research. Some ongoing research projects are a birth control vaccine based on human chorionic gonadotropin, long acting testosterone injectables, an anti-sperm agent from the plant Tripterygium wilfordii, and a large multi-center study of infertility. Some past efforts include the male contraceptive gossypol, now discontinued; the anti-progestin RU-486, now licensed as an early medical abortifacient in France, China and England; and the vaginal hormone-releasing ring, about to be introduced. In support of research HRP has donated grants to 1225 scientists from 375 institutions in 71 countries. It has supplied standardized immunoassay reagents and helped form national and regional reagent programs. Expert meetings and workshops, and the recent global assessment of the program are examples of information dispersal. Another benefit of the program is its effect on enhancing women's status, from improving reproductive choice to enhancing women's participation in reproductive research.
Coping with extra Poisson variability in the analysis of factors influencing vaginal ring expulsions.
STATISTICS IN MEDICINE. 1991 Feb; 10(2):241-54.Statistical modeling of variation in expulsion rates for levonorgestrel- releasing vaginal rings, employing 1st Poisson distribution, models for over-dispersion parameters, and then a truncated Poisson model to account for the variation. The data were a series of trials by WHO on 1005 women in 19 centers in 1 countries. The variables were number of involuntary expulsions, age, parity, ponderal index, number of days of ring use and health care center. In the WHO report, generalized linear models left a remaining variation greater than anticipated if the expulsion event were constantly distributed. The Poisson regression model initially tested here allowed for different number of days of use by women, and assumed that the mean number of expulsions directly proportional to the log of the duration of use. Analysis of deviance suggested that the data were over-dispersed, with a deviance exceeding the degrees of freedom. Possible explanations include: outlying points from women with high numbers of expulsions, variables not included in the data, an underestimated true variance, an incorrect functional form for "f", or an assumed variability between individuals that is not actually the same for all women. A model using an over-dispersion parameter was fitted into the Breslow model and was recomputed until the Pearson X squared statistic was close to the degrees of freedom. After fitting the resulting Poisson model, center and parity were significant. A truncated Poisson model, where centers reporting no expulsions were omitted, showed no over-dispersion. Women of parity 1, 2, or 3 has 1.7 times the rate of expulsion of women of 0 parity, and those with parity >4 has 2.80 times the expulsion rate, possible reflecting relaxation of the vaginal outlet. There was a trend toward higher expulsion during defecation for women from Asian countries, compared to those from Africa, Europe and Latin America.
ADVANCES IN CONTRACEPTION. 1990 Sep; 6(3):169-76.Clinical trials of vaginal rings containing progestins or ethinyl estradiol and progestins by WHO, the Population Council and private firms are reviewed. Contraceptive steroids can be formulated into Silastic vaginal rings because they are released continuously from this material (zero-order kinetics). Vaginal rings have the advantage of avoiding the 1st pass effect on the liver, as well as self- administration, unrelated to the timing of coitus and regulation of withdrawal bleeding with removal for 7 days per cycle. The shell vaginal ring, with an inert core, a layer of Silastic containing the progestogen, and an outer Silastic layer is designed to regulate release by the thickness of the outer layer. The WHO tested rings releasing 200 mcg norethisterone/day resulting in too many menstrual side effects; and 50 mcg/day with too high a failure rate. A ring releasing 20 mcg levonorgestrel is expected to perform well. The Population Council designed rings releasing 152 mcg ethinyl estradiol and 252 mcg levonorgestrel, and 183 mcg ethinyl estradiol and 293 mcg levonorgestrel. These resulted in pregnancy rates of 2/100 woman years, and continuation rates of 50%, but unacceptably adverse lipid effects. Women discontinued for vaginal symptoms. Compared to a similar combined oral pill, the rings offered no advantage. WHO subsequently introduced a ring releasing 20 mcg levonorgestrel: efficacy was 3.8 and continuation over 50%. A new segmented ring with desogestrel is causing fewer androgenic effects and bleeding complaints. Another ring in current trials gives off 120 mcg desogestrel and 30 mcg ethinyl estradiol with no pregnancies and good acceptability in 100 women to date. Availability of Silastic material and quality control in manufacture are seen as obstacles to overcome for mass production of these vaginal rings.
London, England, International Planned Parenthood Federation, 1990. 122 p. (IPPF Medical Publications)This booklet intended for family planning doctors primarily in developing countries updates the previous IPPF edition, with new information on oral contraceptives, chapters on the subdermal implant Norplant, post-coital contraception, injectables, and appendices on statistical methods and post-partum contraception. Each chapter contains text with a statement by the IMAP (International Medical Advisory Panel) of the IPPF. After brief introductions on historical background and reproductive physiology, the main part of the book concerns the use of combined oral contraceptives, their actions, beneficial and adverse effects, indications and contraindications, and several aspects of use such as community-based distribution. There are chapters on progestogen-only pills and on orals in chronic disease. Post-coital contraception is discussed, considering combined pills, progestagens, IUDs, Danazol, RU-486, which all have different time limits of effectiveness. Both DMPA and NET-EN injectables, by 3-month and monthly protocols are described, with a section on the controversy regarding their distribution. The chapter on Norplant comprises mostly the IMAP statement: more information would be needed for training in this method. The book ends with remarks on the use of hormonal contraceptives to enhance safe motherhood, taking into account the fact that the pill offers no protection against STDs.
OUTLOOK. 1990 Jun; 8(2):7-9.This article summarizes the most recent data on WHO's multicenter clinical trial test of the low dose progestin-releasing vaginal ring as an effective contraceptive for women. The study involved 1005 women aged 19-34 and was carried out from 1980-86 at 19 centers in 13 countries, including 9 developing countries. The overall findings on vaginal ring use included: the ring's effectiveness was comparable to oral contraceptive (OC) effectiveness, pregnancy rates increased with increasing body weight, about 1/2 of the users had discontinued the ring by 1 year, the ring disrupted menstrual bleeding patterns in about 1/2 of all users, and about 1/4 of all users expelled the ring at least once but most continued to use it. The irregular bleeding pattern was the main reason for discontinuation. Part of the reason for having different ring contraceptive effectiveness in different countries could be due to differing average weights of the women. Increasing risk of expulsion was directly related to increasing age by approximately 3% with each year of age. For effective use of 90-day low-dose levonorgestrel-releasing vaginal ring, appropriate clients should have the following: a dislike for inserting and removing vaginal devices, low weight, counselling on potentially irregular bleeding, and counseling on how to deal with an expulsion. (author's modified)
CONTRACEPTION. 1988 Aug; 38(2):129-56.Methods of analyzing vaginal bleeding patterns, both of normally menstruating non-contracepting and contracepting women, are reviewed, and the reference period method is described in greater detail. For women using long-acting hormonal methods, the concept of cycle is no longer appropriate. The reference period method adopts the woman as the unit of analysis, divides her menstrual diary into consecutive periods, and summarizes vaginal bleeding patterns within each period. Data are presented in bar plots showing median length of bleeding, 5th and 95th percentiles, means and standard deviations. Natural, oral contraceptive, and IUD patterns are similar, while 3-monthly injections, vaginal rings and minipill patterns are disrupted patterns with no notion of cyclicity. Dealing with events that overlap reference period boundaries is still a problem, and is still being studied by working groups, in particular at WHO and the University of Exeter. For example, the effects of different definitions have not yet been systematically evaluated, and recommendations have not been tested empirically. The WHO has published a set of data on 4817 women's diaries to stimulate statistical research on this topic.
FERTILITY AND STERILITY. 1986 Oct; 46(4):626-30.In a phase 3 clinical trial sponsored by WHO Special Program of Research in Human Reproduction, contraceptive effectiveness and adverse effects were analyzed in 108 women who used the levonorgestrel-releasing vaginal ring. This delivery system releases levonorgestrel at a constant rate in a low dose (20 + or - 3.5 mcg/24 hours) sufficient for contraception without necessarily inhibiting ovulation. 1-year cumulative net rates per 100 women were: pregnancy, 3.7; expulsion, 4.6; use-related discontinuation, 26.9; and continuation, 71.2. Menstrual disturbance (e.g., intermenstrual bleeding, prolonged menstrual flow, amenorrhea) was the main adverse effect and the most common reason for discontinuation. Menstruation disturbances occurred in 45% of the cycles during the 1st month of use, but decreased gradually to 12.5% during the 12th month. Expulsions, which occurred 7.7% of the 963 cycles observed, generally took place during urination or defecation. The duration of menstrual flow was prolonged from 4 to 9 days before insertion to 6.9 after insertion. However, the menstrual blood loss gradually declined after insertion and the hemoglobin concentration was significantly increased in the 6th and 12th months after insertion (p. < 0.05). Analysis of E2 and P in 35 of the treatment cycles in this study indicated that 48.5% were ovulatory. An advantage of the low-dose levonorgestrel-releasing vaginal ring is that there are no significant changes in lipid parameters. Although the high-dose levonorgestrel and estradiol-releasing ring developed by the Population Council is associated with fewer bleeding problems, the low-density and high-density lipoprotein ratio is significantly elevated, with possible implications for the risk of cardiovascular disease. The WHO vaginal ring is likely to be an effective alternative for women who cannot use other currently available contraceptive methods.
In: Long-acting contraceptive delivery systems edited by Gerald I. Zatuchni, Alfredo Goldsmith, James D. Shelton, John J. Sciarra. Philadelphia, Harper and Row, 1984. 246-7.2 principles govern the major methods of vaginal-ring release of steroids: to suppress ovulation and, the route followed by the World Health Organization (WHO), not to suppress ovulation. When ovulation is not suppressed, as with the minipill, high rates of ectopic pregnancy have been associated with the progestin-only method. Also, high rates of ectopic pregnancy have been found for an IUD that does not suppress ovulation and works as a progestin-only device. In the phase 3 ongoing study of the WHO ring in a number of centers, no ectopic pregnancies have been reported thus far. It is unclear whether the RS 37367 enters the circulation and is then secreted in the cervical mucus or whether it is taken up by osmotic, capillary, or other action into the cervical mucus. If an effect on the cervical mucus occurs after the ring has been removed from the vagina, the RS 37367 may be stored in cervical mucus and then released slowly. It appears unlikely that the compound is absorbed systemically and resecreted into mucus because the compound is rapidly metabolized by the liver, and, although radiolabeling indicates that large amounts of radioactivity are circulated in the blood by HPLC, there is no intact compound. In regard to use, there may be more expulsion of vaginal rings in cultures with squatting toilet habits. Also, there may be poor cultural acceptance of a method that requires genital manipulation. In areas where prevailing hygiene conditions are poor, a ring that has to be removed monthly or every 3 months may increase the danger of introducing infection.
JOURNAL OF STEROID BIOCHEMISTRY. 1979 Jul; 11(1B):461-7.This report succinctly summarizes Phase I and II clinical trials of intravaginal and intracervical delivery systems for fertility control agents (both steroidal and spermicidal) performed at World Health Organization (WHO) Centres internationally. The WHO Special Programme has conceived of and developed a number of vaginal rings (silastic), which are capable of achieving constant release rates of progestogenic steroid for periods of 90 or more continuous days of use. The local administration rules out the possibility of systemic side effects while the constant release is capable of inhibiting sperm migration through the cervical mucus efficacy of these devices incorporating norethisterone, levonorgestrel, and progesterone is in progress. The vaginal ring has also been incorporated with nonoxynol-9, a potent spermicidal agent. Constant daily release of this spermicidal agent also inhibits sperm migration in the cervical mucus, and use-effectiveness studies are underway. An inert intracervical device, designed and manufactured by WHO, is described (figures depict its manufacturer), and though it is suitable for constant release contraception, no such studies have been performed as yet. Numerous tables report particular release rate data for the vaginal rings impregnated with various dosages of progestogen or spermicide.
Guide to equipment selection for M/F sterilization procedures. Guide du materiel utilise pour les procedures de sterilisation des hommes et des femmes.
Population Reports. Series M: Special Topics. 1977 Sep; (1): p.This is a guide to aid in selecting and maintaining the proper equipment used in the following sterilization procedures: 1) minilaparotomy, 2) laparoscopy, 3) conventional laparotomy, 4) colpotomy, 5) culdoscopy, and 6) vasectomy. Prototype, experimental, or infrequently used instruments are not discussed. Colpotomy, minilaparotomy, and conventional vasectomy are low-technology procedures requiring relatively simple, locally produced instruments, e.g., retractors, forceps, and scalpels. High-technology equipment consists of specialized items, e.g., laparoscopes and culdoscopes. These are produced in a limited number of technically advanced countries. Equipment donor agencies are discussed. The following factors must be considered in selecting equipment: 1) suitability for the intended procedures, 2) quality of the instrument, 3) ease of repair, and 4) initial cost. Each type of equipment is pictured, diagrammed, described, and charted against others of its kind. Maintenance and repair guidelines are provided.
In: Sciarra, J.J., Markland, C. and Speidel, J.J., eds. Control of male fertility. (Proceedings of a Workshop on the Control of Male Fertility, San Francisco, June 19-21, 1974). Hagerstown, Maryland, Harper and Row, 1975. p. 274-307Literature on research approaches to permanent and relatively reversible methods of male fertility control is reviewed. Sources and expenditures for research into male fertility control are noted. Permanent methods discussed include electrocautery of the vas, transcutaneous interruption of the vas, vasectomy clips, chemical occlusion of the vas, and passive immunization. Reversible methods reviewed include vasovasotomy, intravasal plugs, and vas valves. Current research into animal models, reversibility after vas occlusion, nonocclusive surgical techniques, pharmacological alteration of male reproductive function, including adrenergic blocking agents, steroidal compounds, inhibitors of gonadotropin secretion, clomiphene citrate, organosiloxanes, prostaglandins, alpha-chlorohydrin, heterocyclic agents, and alkylating agents, and delivery systems for antifertility agents is discussed. Research into semen storage and improved condoms is also reviewed. As a relatively low proportion of funds are committed to research in male fertility control, a greater investment in applied and clinical research is warranted.
In: Goldsmith A, Toppozada M, ed. Long-acting contraception. Chicago, Illinois, Northwestern University, Program for Applied Research in Fertility Regulation [PARFR], 1983. 137-46.The characteristics and clinical performance of subcutaneously and vaginally implanted vaginal rings, under development for the past 15 years, are reviewed. This development has been restricted to public sector agencies, including the World Health Organization (WHO) and the Population Council, reflecting the lack of interest of the pharmaceutical industry in this area. Currently, only 1 progestogen-only releasing device is under development. The ring, which releases 20 mcg/day of levonorgestrel, produces plasma concentrations averaging 0.528 pmoles/ml, with a 20% decline in these concentrations 90 days after insertion. Ovulation was not inhibited in 90% of subjects studied in clinical trials, although inhibition of sperm transport in cervical mucus was noted in 85%. A WHO-sponsored Phase I trial of vaginal rings releasing progesterone, norethisterone, and levonorgesterel resulted in abandonment of development of the 1st 2 steroids. No pregnancies were noted in 360 woman-months of use of levonorgestrel-releasing rings. Phase II studies with these rings produced encouraging results, and results of Phase III multicenter clinical evaluations should be available by late 1983. In an attempt to improve bleeding performance, rings capable f releasing both an estrogen and a progestogen have been develeped under the auspices of the Population Council. 2 progestational agents--progesterone and levonorgestrel--coupled with estradiol have been used in these studies. Results with the levonorgestrel-estradiol ring have been most promising. A clinical trial involving 1147 users compared the pregnancy rate obtained with 2 such rings, 1 with a 58 mm outer diameter and 1 with a 50 mm diameter, to that with a low lose oral contraceptive (OC) containing 150 mcg levonorgestrel and 30 mcg ethynilestradiol. The 58 mm diameter ring produced only 5 pregnancies in 1 year of of use, compared with 9 pregnancies with the 50 mm ring and 10 pregnancies with the OC. Tests in both urban and rural areas of 2 Latin American countries found that 3-12.5% of total acceptors accepted the rings, with higher percentages in the rural areas. Acceptability fell after 6 months of use and recovered in the 2nd year. Since both the ovulation inhibiting discontinuous use ring and the low dose continuous use device are at the Phase III level, this new form of contraception may be available within the next few years.
In: Assessment of the WHO Special Programme of Research, Development and Research Training in Human Reproduction [HRP]. II. Task Force reports. Country reports, [compiled by] Sweden. Swedish Agency for Research Cooperation with Developing Countries [SAREC]. Stockholm, Sweden, SAREC, 1983 Apr. 14 p..In interim report on the WHO Special Programme of Research, Development and Research Training in Human Reproduction Programme's work on long- acting hormonal contraceptives: injectables, biodegradable and nonbiodegradable subcutaneous implants, and vaginal rings as of 1983 is presented. Prior work from the HRP Programme led to keeping Depo- Provera on the market, except in the US, and adjusting the dose of norethisterone enanthate to 200 mg bimonthly. Continuing research on medroxyprogesterone acetate injectables with lower doses, and biological effects during lactation is suggested. One of HRP's goals is to develop a long-acting, reversible contraceptive that does not inhibit ovulation, but also does not cause ovarian cysts, ectopic pregnancy or menstrual irregularity. Monthly combined injectables, longer-acting injectables, vaginal rings and biodegradable implants are potential candidates. The contraceptive should be inexpensive, attractive to users, and easy to apply without medical intervention. Norplant and Capronor, a biodegradable subcutaneous implant, are being tested. While the HRP program has not come up with any new steroid agents, it has been beneficial in research training and institutional development.