Mesigyna once-a-month combined injectable contraceptive: experience in Latin America

A phase III clinical study was carried out among 534 fertile Latin American women to evaluate cycle control, side effects, and contraceptive efficacy of a once-a-month combined injectable, Mesigyna, consisting of 50 mg norethisterone enanthate and 5 mg estradiol valerate. The pregnancy rate at 1 year was 0 per 100 woman-years for a total experience of 4688 woman-months. The overall discontinuation rate at one year was 17.9%. Discontinuation rate for bleeding problems was 5.1%. The Colombian women had a significant increase (p <0.001) in bleeding problems compared to other countries. The discontinuation rate for amenorrhea was 1.1%. There were no significant differences between the groups regarding discontinuation for other medical or non-medical reasons. Mean weight gain after one year of use was 1.02 kg. Mesigyna is an appropiate once-a-month injectable contraceptive for Latin American women since it is highly effective and its perception of normal menstrual bleeding is of importance in the Latin American population.

Cyclofem/Cyclo-Provera: emerging countries' perspective

Cyclo-Provera, the original name of the combination of 25 mg medroxyprogesterone acetate and 5 mg estradiol cypionate, later known as Cyclofem and hereafter referred to MPA/E2C, has proven its use-effectiveness (pregnancy rate less than 1%) in routine service delivery conditions. Overall, the life-table discontinuation rates at 1 year ranged from 33.5% to 71.8%. Only a third of total discontinuations were attributable to the injectable contraceptive method, thus raising the importance of service delivery issues related to its continued use. The results of introductory trials in Mexico, Indonesia, Thailand, Tunisia, Jamaica and, more recently, Brazil, Colombia, Chile and Peru have demonstrated that MPA/E2C is a highly effective contraceptive that could be offered as an alternative to current fertility regulation methods for many women around the world. In addition, the results of studies were the basis for the approval of MPA/E2C by local health authorities and its inclusion in the Ministries of Health Family Planning Programs.

Reversible contraception: issues faced by emerging countries

There is no doubt that fertility regulation represents an important contribution to reproductive health. The role of fertility regulation in decreasing maternal mortality has been well documented. Thus, the use of contraceptives in developing countries has been projected to increase from 51% (1990) to 59% in the year 2000. Accordingly, 151 million surgical procedures for female and male sterilization, 8.7 billion cycles of oral contraceptives (OCs), 663 million doses of injectables, 310 million intrauterine devices (IUDs), and 44 billion condoms will be required in developing countries during the 1990s. Contraceptives are currently being manufactured in at least 27 developing countries. Subsidiaries of multinational companies are often involved in the local production of OCs and condoms, whereas most domestic IUD manufacturing ventures have been undertaken by local private companies. External assistance agencies have been active in supporting the local production of contraceptives.

Introduction of cyclofem once-a-month injectable contraceptive in Mexico

A large introductory study of Cyclofem, a once-a-month injectable contraceptive, was conducted in three Mexican provinces. A total of 3457 healthy women participated: 640 women from rural areas (community-based component) and 2817 women from urban and suburban areas (health center-based component). A total of 20,316 women-months of treatment experience were accumulated during a one year period. Cyclofem proved its use-effectiveness (pregnancy rate of 0.03%) and its safety under routine service conditions of family planning facilities in Mexico. The overall life table continuation rate at 1 year was 26.1%. Higher continuation rates were observed in the community-based component (36.6%) as compared to the health center component (23.7%). The most common reason for method discontinuation was change of address. Only 15% of the discontinuations were attributable to the injectable contraceptive method, with the overall 1 year discontinuation rate for bleeding problems (including amenorrhea) was < 11%. These observations underscore the importance of appropriate counseling and follow-up measures, providing convenient access to repeat injections, and other service delivery issues related to continuation of Cyclofem. The results of this trial have once again demonstrated that Cyclofem is a highly effective method with an acceptable side effect profile. In addition, the study provided the elements for its approval by local health authorities and its inclusion into the Ministry of Health Family Planning Program.

A multicenter comparative study on the efficacy, safety, and acceptability of the contraceptive subdermal implants Norplant and Norplant-II

In order to assess efficacy, safety, and acceptability of the contraceptive subdermal implants Norplant and Norplant-II in Mexican women, a comparative phase III clinical trial was undertaken in eight clinics across the country. The study involved 1052 women who were followed-up trimonthly for three years. Cumulative pregnancy rates were 0.29% and 0.34% for Norplant and Norplant-II implants, respectively. Similar overall cumulative discontinuation rates were observed at three years: 50.38% for Norplant capsules, and 50.44% for Norplant-II rods. The main method-related reason for termination was endometrial bleeding irregularity which led to discontinuation rates of 11.94% and 11.62% for Norplant and Norplant-II contraceptive systems, respectively. In 15,279 woman-months of experience accumulated with Norplant implants and 14,092 with Norplant-II implants, there were few adverse events reported. No difference was found between the two groups in either difficulty for implants placement and removal or women's discomfort, even though the time required for insertion and removal of Norplant capsules was longer than for Norplant-II rods. It is concluded that during the first three years of use, both implants systems are equally effective, safe, and acceptable.

Ability of an anti-luteinizing hormone-releasing hormone vaccine to inhibit gonadotropins in postmenopausal women

OBJECTIVE

To determine the effects of immunization with an anti-LH-releasing hormone (LH-RH) vaccine in postmenopausal women.

DESIGN

Pilot clinical study.

SETTING

Normal human volunteers in a medical research-training environment.

PATIENT(S)

Three postmenopausal women with a mean age of 60 years, 5 years of amenorrhea, and severe hypoestrogenism with elevated serum LH and FSH.

INTERVENTION(S)

Intramuscular immunization with 300 micrograms LH-RH equivalent of the vaccine in two occasions 1 month apart.

MAIN OUTCOME MEASURE(S)

Patients were followed for clinical assessment and serum LH, FSH, and anti-LH-RH titers at regular monthly intervals for 7 months.

RESULTS(S)

The injection of the anti-LH-RH vaccine followed by a booster injection 1 month later resulted in a sharp decrease, 60 days after the first injection, of both serum gonadotropins, accompanied by an increase in anti-LH-RH antibody titers, which were reversible after 180 days in the absence of further booster immunization.

CONCLUSION(S)

Active immunization offer a safe option to induce antibody response, which in the present regime employed was of about 6-months duration. This procedure opens new possibilities for its use as an affordable therapeutic agent in some hormone-dependent clinical conditions.

Review of ovulation return upon discontinuation of once-a-month injectable contraceptives

Once-a-month combined injectable preparations draw their contraceptive efficacy from continuous ovulation suppression. When their use is discontinued, ovulation resumes within a few weeks or a few months, depending on the formulation. After use of the dihydroxyprogesterone acetophenide 150 mg/estradiol enanthate 5 mg combination for one to two years, ovulation returns in most subjects 3-4 months after discontinuation of treatment. Similarly, recent data show that after 2-year use of the depot-medroxyprogesterone acetate 25 mg/estradiol cypionate 5 mg or the norethisterone enanthate 50 mg/estradiol valerate 5 mg combination, approximately 70% women have resumed ovulation by the third month post-treatment. This is shorter than the time for return of ovulation experienced by ex-users of progestogen-only injectable contraceptives.

Pharmacokinetics of once-a-month injectable contraceptives

The addition of a short- or medium-acting estrogen ester to the long-acting progestins depot-medroxyprogesterone acetate (DMPA) and norethisterone enanthate (NET-EN) to produce "combined" injectable formulations has proved a successful strategy in the development of once-a-month injectable contraceptives. Recent clinical pharmacokinetic studies undertaken on once-a-month injectable contraceptives in various WHO Collaborating Centers have guided the selection of the estrogen-progestogen combinations, ratios and dose schedules. At least three combined once-a-month injectable preparations exhibit acceptable pharmacokinetic and pharmacodynamic profiles; however, further improvement in the design of optimal estrogen/progestin injectables are expected during this decade.

Safety and efficacy of a combined oral contraceptive: gestodene 75 micrograms plus ethinyl estradiol 30 micrograms in Mexican women

An open prospective clinical trial designed to evaluate the efficacy and safety of the combined hormonal oral contraceptive (OC) containing 75 micrograms gestodene plus 30 micrograms ethinyl estradiol was undertaken in a Mexican population. Sixty-nine healthy women of reproductive age took part in the study for a total of 627 woman-months of observation. The combination of gestodene and ethinyl estradiol proved its effectiveness in preventing pregnancy during the study. Side-effects were minimal and regular endometrial bleeding patterns were observed during one year of continuous use of this OC preparation. The discontinuation rate for medical reasons was 11.6% at one year. Among a sample of 10 women, the gestodene/ethinyl estradiol combination did not induce significant changes in the serum concentration of total cholesterol and LDL cholesterol after 12 months of continuous administration. An increase in serum triglycerides and HDL cholesterol was observed; this effect could be attributed to a lack of androgenic and/or the intrinsic estrogenic behavior of gestodene. It can be concluded that this preparation is highly effective as a combined oral contraceptive; it is well tolerated and might offer some advantages with respect to other oral contraceptive combinations in its short- and medium-term impact on lipid metabolism.

Comparative effects of short term treatment with norethisterone and sex steroids on gonadotropin secretion in rat pituitary cell cultures

The short term effects of norethisterone (NET), progesterone (P), estradiol (E2) and dihydrotestosterone (DHT) on the gonadotropin secretion of pituitary cells, from both male and female rats, in primary culture primed with E2 were studied. In female cells, NET only increased the GnRH-induced secretion of LH, while P increased both LH and FSH. Male pituitary cells showed an increased response to GnRH after P pretreatment only if the E2 concentration was augmented. However with the same E2 conditions pretreatment with NET decreased the stimulated LH, but not FSH secretion. Pretreatment with E2 inhibited LH stimulated secretion from pituitary cells of male but not female rats. Furthermore DHT treatment diminished the GnRH response for both LH and FSH in pituitary cells from both sexes. Androgen pretreatment increased basal gonadotropin secretion in male but not in female cells. Basal FSH secretion was increased by NET pretreatment in male cells. This suggests that NET is metabolized by cultured pituitary cells to A-ring reduced compounds during the 4 h incubation period. The formation of NET metabolites, particularly the 3 beta, 5 alpha and 5 alpha-NET might be responsible for the estrogenic and androgenic effects observed when NET was administered to the cultured pituitary cells.

[Comparison of the DELFIA and RIA methods for measuring luteinizing and follicle stimulating hormones in serum]

Hormonal quantitation has had important developments since Yalow and Berson created the first radioimmunoassay for insulin in 1959. Since then much research has been done to find new non-isotopic methods which offer better levels of sensitivity, specificity and precision than RIA. DELFIA (dissociation enhancement lanthanide fluoroimmunoassay) is a new alternative technology which is a specific time resolved fluoroimmunoassay (TR-FIA) which combines higher purified antigens, monoclonal antibodies in a sandwich type assay with long fluorescence decay time of lanthanide chelates as europium, samarium and terbium used as labels, and a particular time resolving fluorometer for nanoseconds measurements. As part of the validation and introduction of the DELFIA method in our laboratory we made a comparative evaluation of DELFIA and RIA in the quantification of serum luteinizing hormone and follicle stimulating hormone. The data favor the DELFIA method in terms of sensitivity, specificity, volume of sample, half life of reagents, as well as the elimination of radioactive tracers.

A multicentre comparative study of serum lipids and apolipoproteins in long-term users of DMPA and a control group of IUD users. World Health Organization. Task Force on Long-Acting Systemic Agents for Fertility Regulation Special Programme of Research, Development and Research Training in Human Reproduction

A clinical trial was conducted in three centres to assess the effects of long-term use of the injectable contraceptive depot-medroxyprogesterone acetate (DMPA) on lipid metabolism. Fifty women who had used DMPA at a dose of 150 mg every three months for 3 to 9 years were recruited in Bangkok, Christchurch and Mexico City. They were compared to a control group of 120 IUD users. Total cholesterol, LDL-cholesterol, HDL-cholesterol, total triglycerides, apolipoproteins AI, AII and B were measured throughout one injection interval. Significant findings differed between centres. Compared to their own centre controls, DMPA users in Bangkok had higher LDL-cholesterol levels; those in Christchurch had lower HDL-cholesterol, apolipoprotein (apo) AI and apo AI/B ratio and higher apo B levels; those in Mexico City had a lower apo AI/B ratio. Further changes were observed during the injection interval, some of which were correlated to changes in serum MPA levels. It is concluded that long-term use of DMPA induces moderate changes in lipid metabolism which are unfavourable in terms of risk for atherosclerosis. This should be borne in mind when weighing the overall risks and benefits of this contraceptive method for a potential user.

Comparative assessment of two low-dose oral contraceptives, Lo-Femenal and Lo-Estrin, in Mexican women

This trial was designed to determine the differences in effectiveness, clinical acceptability, and one-year discontinuation rates of two low-dose oral contraceptives: Lo-Estrin (norethindrone acetate 1.5 mg plus ethinyl estradiol 0.030 mg) and Lo-Femenal (norgestrel 0.30 mg plus ethinyl estradiol 0.030 mg) in 148 Mexican women. In addition, the effects of both oral contraceptive preparations on blood lipids were prospectively evaluated in a subgroup of 41 women. The results indicated that there were no differences in pregnancy rates, discontinuation or clinical acceptability between the two groups. The lipid changes observed were minimal for the Lo-Femenal subgroup and somewhat greater for the Lo-Estrin group, mainly an increase in serum triglycerides. These changes were interpreted as estrogen induced effects of norethindrone-containing oral contraceptives. Overall, the data indicate that both Lo-Femenal and Lo-Estrin are effective and safe combined oral contraceptives.

The effects of opioid blockade and GnRH administration upon luteinizing hormone secretion in patients with anorexia nervosa during the stages of weight loss and weight recovery

OBJECTIVE

We examined the functional status of the hypothalamic-opioid system involved in LH secretion and the pituitary LH sensitivity and reserve in patients with anorexia nervosa were studied during body weight loss and weight recovery. We measured the temporal relationship between weight recovery, expression of hypothalamic-opioid activity and pituitary GnRH responsiveness, and resumption of ovulatory cycles.

DESIGN

Five patients with anorexia nervosa were prospectively studied during weight loss and amenorrhoea, subsequently when they reached their ideal body weight but still remained amenorrhoeic and thereafter every 6 months until resumption of ovulatory cycles; one patient was studied only during weight loss, two during ideal body weight and amenorrhoea and one during ideal body weight and ovulatory cycles. Blood was sampled every 10 minutes over a 16-hour period on two alternate days. On study day 1 (control day), patients received two sets of saline infusion every 6 hours and one saline bolus at the beginning of the seventh hour; on study day 3 (experimental day), they received a saline infusion during the first 6 hours, an intravenous bolus of naloxone (20 mg) at the beginning of the seventh hour and then a continuous naloxone infusion (1.6 mg per hour) during the ensuing 6 hours. Pituitary LH sensitivity and reserve were assessed on both study days by the subsequent administration of 5 and 95 micrograms of GnRH 4 hours before the completion of each sampling period. Patients in ideal body weight and ovulatory cycles as well as five normal menstruating women included in the study for comparative purposes, were studied during the midluteal phase of a cycle.

MEASUREMENTS

LH, oestradiol and progesterone were determined by radioimmunoassay. Areas under the LH curve were calculated by the trapezoid method; LH pulse detection was carried out by the program Cluster.

RESULTS

Naloxone administration to patients with anorexia nervosa in the weight loss phase, did not significantly modify their serum LH levels nor the characteristics of its pulsatile secretion. Administration of the opioid blocker induced a significant increase in serum LH concentrations only in those patients in ideal body weight and amenorrhoea who resumed ovulatory cycles within the 6 months following the last study as well as in patients with an ideal body weight and ovulatory cycles and in normal controls. All patients and subjects who responded to naloxone administration exhibited significant increases in the area under the LH curve, mean LH pulse amplitude and peak area. Patients in ideal body weight and amenorrhoea who did not resume ovulatory cycles within the 6 months following the study days, did not respond to naloxone administration. There were no significant correlations between the magnitude of LH response to naloxone administration and the baseline levels of serum oestradiol and progesterone. All patients exhibited significant pituitary LH responses to both GnRH doses, regardless of the stage of the disease; however, the pituitary responsiveness shown by patients in ideal body weight was significantly higher than that presented by patients in weight loss. There were no significant differences between the responses to GnRH exhibited by patients in ideal body weight and amenorrhoea who responded to naloxone administration and those shown by patients in the same clinical condition but who were insensitive to opioid blockade.

CONCLUSIONS

The re-establishment of hypothalamic-opioid inhibitory activity involved in LH secretion in patients with anorexia nervosa during the phase of weight gain predicts imminent restoration of ovulatory cycles. Pituitary LH response to exogenous GnRH during weight recovery does not accurately predict the outcome of the disease regarding reinitiation of menstrual cycles; however, it might be an indicator that the normal function of the hypothalamic-pituitary axis is being restored.

Assessment of luteal function after surgical tubal sterilization

To evaluate ovarian luteal function after tubal occlusion, a group of women who underwent Pomeroy sterilization were studied. A prospective group I (n = 16) were followed for one year and scheduled for blood sampling every other day during their luteal phase before surgical procedure and at 3 and 12 months thereafter. Group II (n = 15) included women who were studied during their luteal phase at 1 or 5 years post-surgery. Mid-luteal progesterone and estradiol serum levels were calculated by estimating the average of at least 3 values of serum samples obtained in days 20-25 of a menstrual cycle. The data suggest that no major changes occur in ovarian function after surgical tubal occlusion, as assessed by the mid-luteal hormone serum levels, and underscore the safety of this procedure.

Long-term effects of depot-medroxyprogesterone acetate on lipoprotein metabolism

To assess the effects of depot-medroxyprogesterone acetate (DMPA) upon serum lipids and lipoproteins, a comparative study in chronic users and new acceptors was undertaken. Two groups of women of reproductive age were included in the study; group I (n = 8) was formed by new acceptors whereas, group II (n = 14) constituted DMPA users of more than five continuous years (7.0 + 2.1 years). Blood samples were taken on the day of injection and 15, 29, 57 and 92 days after the i.m. administration of 150 mg of DMPA for the measurement of total triglycerides (TG), cholesterol (CHOL) and phospholipids (PHL). In addition, the TG and CHOL content in the very low density (VLDL), low density (LDL) and high density (HDL) lipoprotein fractions obtained by ultracentrifugation were also determined. The results demonstrated a moderate increase in the serum total TG concentrations at the expense of the VLDL fraction in the group of chronic DMPA users. In both groups, the administration of DMPA induced a moderate, though not significant, decrease in total CHOL and HDL-chol, an effect that was noticed at the end of the treatment interval; the serum LDL-chol content remained unchanged. In addition, a decrease in the total serum phospholipids content was noticed after DMPA injection in both groups, which resembled the fluctuations observed in the luteal phase of normal ovulating women. The overall data indicate that acute and/or chronic DMPA administration at the dose currently employed for contraception does not induce major abnormalities in lipoproteins in serum.

A pilot study on the assessment of a progesterone/estradiol sustained release as once-a-month-injectable contraceptive

A pilot study to assess the use of natural hormones in macrocrystalline sustained release system was undertaken in normal menstruating women. Progesterone at a dose of 100 mg in combination with 5 mg estradiol-17 beta aqueous macrocrystalline suspension (3ml) of defined particle size range (100-250 microns) were administered to five female volunteers of reproductive age, on day 5 of their normal menstrual cycles and then every 28 days consecutively for the next two months. Peripheral venous blood samples were obtained from the women three times a week for 60 days after the third injection for the measurement of serum progesterone, estradiol-17 beta, LH and FSH. The menstrual bleeding patterns were closely monitored during the study period. The results obtained indicate that the exogenous hormone administration produces blood levels similar to those observed during the luteal phase of the menstrual cycle. Follicular maturation as assessed by endogenous estradiol rise, above 150 pg/ml, occurred 29.7 days s.d. 6.4 after the injection. Ovulation as measured by progesterone levels above 5 ng/ml was documented 34.4 days s.d. 4.3 after the third injection. The bleeding patterns were regular though initially shorter but these increased progressively towards normal pattern during course of the study. The data suggest that progesterone/estradiol-17 beta combination administered as an aqueous macrocrystalline suspension is capable of producing sustained ovulation inhibition and could be applied in the design of new once-a-month injectable contraceptives.

Long-acting hormonal contraceptives for women

Following the development and widespread use of oral hormonal contraceptives, it became evident that alternative long-acting delivery systems would be required to improve contraceptive practice in some cultural settings where injectable or subdermal routes of administration are preferred. Nowadays, long-acting contraceptives constitute an important option in family planning services in many parts of the world. Indeed, two long-acting injectable contraceptives containing just a synthetic progestogen (depot-medroxyprogesterone acetate (DMPA) and norethisterone enantate (NET-EN)) have been in clinical practice for more than 20 years. The World Health Organization's (WHO) Special Programme of Research in Human Reproduction, in collaboration with the U.S. National Institute of Child Health and Human Development (NICHD) and universities primarily in developing countries undertook a synthesis programme aimed at producing an improved injectable preparation by developing new derivatives of known steroids. One such compound (levonorgestrel 17-butanoate) is now at the stage of Phase II clinical testing. In addition, the Special Programme has developed and improved once-a-month injectable formulations and assessed their safety and efficacy in different countries worldwide. After large scale clinical testing, at least two progestogen-estrogen combinations have reached the point of introductory trials.

Further studies on the antigonadotropic mechanism of action of norethisterone

To examine the molecular mechanisms involved in the antigonadotropic effects of norethisterone (NET) and two of its A-ring reduced metabolites the 5 alpha-norethisterone (5 alpha-NET) and the 3 beta, 5 alpha-norethisterone (3 beta, 5 alpha-NET) at the neuroendocrine level, a series of experiments were undertaken in adult castrated rats. Animals were primed either with 0.2 mg of tamoxifen (Tam) for 4 consecutive days or 1.0 mg of cyproterone acetate (CPA) for 7 days followed by a single subcutaneous injection of 0.5 mg of NET, 5 alpha-NET or 3 beta, 5 alpha-NET. Four hours later, they were sacrificed and blood obtained for the measurement of immunoreactive serum LH and FSH. The results indicated that antiestrogen (Tam) pretreatment precluded the inhibitory effects of NET and the 3 beta, 5 alpha-NET but not those of the 5 alpha-NET derivative. Pretreatment with CPA did not modified the antigonadotropic action of the 3 beta, 5 alpha-NET metabolite but it markedly reduced the inhibitory action of the 5 alpha-NET, thus indicating that in the experimental model used, the antigonadotropic effects of NET, are in part the result of its metabolic conversion to its A-ring reduced metabolites. While the 5 alpha-NET displayed an androgenic effect, the 3 beta, 5 alpha-NET exhibited estrogen-like effect at the neuroendocrine level.

[Data analysis and quality control in radioimmunoanalysis. II. Evaluation of the internal and external quality in the quantification of pituitary gonadotropins]

The procedures for a systematic evaluation of the quality control of radioimmunoassay in general were described previously. In this report we present the parameters of quality control and their application to the radioimmunoassay (RIA) of pituitary gonadotrophic hormones, luteinizing hormone (LH) and follicle stimulating hormone (FSH) in serum. We present the results obtained in the intra-assay variation for the measurement of the pituitary gonadotrophic hormones in serum (LH and FSH) from 1983 to 1989. The results on bias and the inter-laboratory assessment through an external quality control scheme during the same period are also presented.

Changes in the responsiveness of prolactin secretion to dopaminergic blockade and TRH stimulation throughout sexual maturation in men

The pituitary prolactin (PRL) response to domperidone (DOM; a dopaminergic antagonist) and TRH administration in human males during different stages of sexual maturation was investigated. Dopaminergic blockade caused an immediate and significant PRL release in all subjects, regardless of the stage of pubertal development. Even though the mean values of peak PRL levels, magnitude of PRL response (delta PRL) and areas under the PRL curve were not significantly different among the different groups, all these parameters showed a clear tendency to increase in parallel to the stage of pubertal development, as indicated by significant positive correlations between age and pubertal stage of the subjects and the magnitude of their PRL response to DOM (r = 0.661, p less than 0.01 and r = 0.536, p = 0.01, respectively). Significant positive correlations also were found between the serum sex steroid hormone concentrations and the PRL response to dopaminergic blockade (r = 0.774, p = 0.02 and r = 0.554, p = 0.01, respectively). In contrast to these findings, no significant differences or tendencies were detected in the PRL responses to TRH among the different subject groups. The different patterns of PRL response to DOM and TRH throughout male puberty might be due to differences in pituitary thresholds for sex steroids between the dopamine- and TRH-dependent intracellular pools.

Long-acting estrogenic responses of estradiol fatty acid esters

Estradiol esters at C-17 and C-3 with palmitic, stearic and oleic acids were chemically synthesized and then evaluated for their long-acting estrogenic responses in ovariectomized rats. The duration of the biological effects was measured after a single subcutaneous dose of 0.1 mumol of each ester and compared with those observed with 17 beta-estradiol, estradiol 3-benzoate and estradiol 17-enanthate. Vaginal citology, uterophyc action, serum gonadotropins inhibition and 17 beta-estradiol levels were measured 0, 5, 10, 20, 30 and 60 days after injection. The results disclosed that most of the estradiol derivatives evaluated exhibited a long-acting estrogenic action. However, the monoesters at C-17 showed longer effects that monoesters at C-3, while the estradiol diesters exhibited the shortest effects. In addition as shown by its low serum levels, all estradiol esters with unsaturated fatty acids show a decreased E2 absorption. The overall results indicated that esterification of E2 with long chain fatty acids provided long-acting properties to it, being higher with C-17 esters. Whether some of these compounds could be employed in substitutive endocrine therapy remains to be established.

Estrogen-progestogen once-a-month injectable contraceptives and serum prolactin

To assess the effect of hormonal monthly injectable contraceptives upon the serum values of immunoreactive prolactin (Prl), three groups of women of reproductive age exposed to different estrogen-progestogen injectable formulation for a minimum of one year were studied. The first group (n = 10) received dihydroxyprogesterone acetophenide 150 mg and estradiol enanthate 10 mg (DHPA/E2-EN), Group 2 (n = 21) received medroxyprogesterone acetate 25 mg and estradiol cypionate 5 mg (MPA/E2-C) and Group 3 (n = 19) was exposed to norethisterone enanthate 50 mg and estradiol valerate 5 mg (NET-EN/E2-V). A group of IUD users (n = 16) served as the control group. Serum Prl and 17 beta-estradiol (E2) concentration were determined in blood samples (0 and 15 min.) on days 0 (day of last injection), 10, 20 and 30 after last contraceptive injection. The results demonstrated a slight though not significant increase (p greater than 0.05) in serum Prl in the three experimental groups as compared with the IUD control group. This increase in Prl levels observed on day 10 post-last injection never exceeded the upper limits of the normal range (20 ng/ml). Overall, the data demonstrated that the chronic administration of these estrogen/progestogen once-a-month injectable contraceptives does not affect the Prl baseline secretion in women.

Absorption of dihydrotestosterone (DHT) after its intramuscular administration

In order to produce a sustained release system for natural androgens, two groups of six hypogonadal males received intramuscular (IM) 40 mg crystalline dihydrotestosterone (DHT), either with particle size of less than 50 microns (DHT-M) or between 100 and 150 microns (DHT-C). Serum DHT was analyzed through 51 days of follow-up. In the DHT-M group, serum DHT was above pretreatment values for 17 days, whereas in the DHT-C group, this period was extended over 50 days. The area under the serum concentration-time curve and the half-life of absorption calculated for the DHT-C group were greater than those obtained for the DHT-M group (55.1 ng/day/ml and 21 days vs. 14.5 ng/day/ml and 6 days; P less than 0.01). The authors conclude that DHT injection appears to be an effective and convenient technique for restoring serum physiologic DHT levels. This approach is suitable for long-term substitution therapy.

A multicentre comparative study of serum lipids and lipoproteins in four groups of oral combined contraceptive users and a control group of IUD users. World Health Organization. Task Force on Oral Contraceptives

A prospective clinical trial was conducted in three centres to assess the effects of the type and dose of progestogen, the dose of estrogen and the progestogen-to-estrogen ratio of oral contraceptives on lipid metabolism. The preparations selected contained levonorgestrel 250 micrograms + ethinyl estradiol 50 micrograms (Neogynon), levonorgestrel 250 micrograms + ethinyl estradiol 30 micrograms (Eugynon 30), levonorgestrel 150 micrograms + ethinyl estradiol 30 micrograms (Microgynon) or norethisterone acetate 1 mg + ethinyl estradiol 50 micrograms (Minovlar). Four-hundred-and-seven premenopausal women were randomly assigned to one of the four pill groups and compared to a control group of 119 users of a CuT220c intrauterine device. Total cholesterol, HDL-cholesterol, LDL-cholesterol and total triglycerides were monitored and the analysis includes the data of those who were followed over 48 weeks, 241 OC users and 87 IUD users. 250 micrograms of levonorgestrel were found to induce more unfavourable lipid changes in terms of atherosclerotic risk than 1mg of norethisterone acetate. Levonorgestrel was found to have a dose-effect on HDL-cholesterol and LDL-cholesterol serum levels, while ethinyl estradiol had a dose-effect on serum triglycerides. HDL-cholesterol was related to the progestogen-to-estrogen ratio. Most of these findings were consistent across centres. Finally, some comments are made on the implications of the study results on the design of future lipid studies.

Changes in the responsiveness of luteinizing hormone secretion to infusion of the opioid antagonist naloxone throughout male sexual maturation

The present study investigated the time of male sexual maturation during which hypothalamic inhibitory opioid activity can be detected. Normal prepubertal (Tanner stage G 1 (Ts-G1) (n = 4], early pubertal (Ts-G2 (n = 5], pubertal (Ts-G3 (n = 4), and Ts-G4 (n = 2] and adult subjects (Ts-G5 (n = 4] receives a rapid infusion of the selective opiate antagonist nalocone (NAL) (20 mg over 10 min). LH secretion was assessed by frequent (every 10 min for 2 h) venous sampling before and after administration of the opiate blocker, as well as by the LH response to exogenous GnRH. All but one (a Ts-G2 subject) pubertal boys showed aprompt and sustained increase in serum LH concentrations after NAL administration, as disclosed by the areas under the LH curve (aLHc) calculated from samples obtained before and after NAL infusion (aLHc in four Ts-G2 responders, 162 +/- 20 (mean +/- SEM) vs 314 +/- 56 mIU/ml/min before and after NAL respectively, P less than 0.025; Ts-G3, 227 +/- 35 vs 362 +/- 56 mIU/ml/min, P less than 0.025; Ts-G4 and Ts-G5, 432 +/- 77 vs 687 +/- 91 mIU/ml/min, P less than 0.05). In contrast, none of the prepubertal children had significant changes in LH secretion after the NAL challenge (154 +/- 17 vs 154 +/- 9 mIU/ml/min). Although all NAL responders exhibited serum testosterone (T) levels above 5 nmol/l, a positive correlation between individual T values and magnitude of LH responses to NAL was not found. All subjects had significant serum LH increments after GnRH administration. In a second series of studies, additional groups of Ts-G1 subjects were primed during 5 days either with GnRH alone or with GnRH plus sex steroids (ethinyl oestradiol 12.5 micrograms/12 h or testosterone enanthate 1.8 mg/kg body weight (single dose], before NAL administration, to investigate whether hypothalamic opioid activity might be unmasked by additional sex steroids. None of the priming schemes significantly modified the pituitary LH responses to NAL infusion (GnRH-primed group, 145 +/- 48 vs 139 +/- 43 mIU/ml/min before and after NAL, respectively; GnRH plus ethinyl oestradiol-primed group, 124 +/- 42 vs 107 +/- 34 mIU/ml/min; GnRH plus testosterone enanthate-primed group, 64 +/- 10 vs 57 +/- 24 mIU/ml/min). This study suggests that the development and/or maturation of the opioid control of LH secretion is temporally related with the onset of puberty.(ABSTRACT TRUNCATED AT 400 WORDS)

Serum estrogens and ovulation return in chronic users of a once-a-month injectable contraceptive

To determine whether the long-term exposure to a monthly injectable contraceptive, containing dihydroxyprogesterone acetophenide 150 mg and estradiol enanthate 10 mg, induces significant changes on the serum estrogens profile and ovulation return in women, a study in chronic users was undertaken. Ovarian function was assessed for 3 months following a single injection of the contraceptive agent in a group of women (n = 7) who have been on this formulation for an average period of 6.7 years and in a non-user control group (n = 7). The serum concentrations of 17 beta-estradiol, estrone and progesterone were measured in samples drawn at regular intervals throughout the entire study. The endometrial bleeding pattern was recorded in all subjects. The results indicated that the post-injection serum estradiol maximum levels (exogenous peak) occurred significantly earlier (p less than 0.05) in chronic users as compared with the non-user control group. Baseline serum estrone concentrations were slightly higher in chronic users than those observed in the control group, while the values of serum 17 beta-estradiol did not exhibit significant differences among the two groups. Ovulation was documented within 60-90 days after injection in all subjects from both groups. A similar length of the first bleeding-free period was observed in all participants. The overall data provide evidence of a moderate increase of estrone, one of the still active metabolic conversion products of 17 beta-estradiol, in the sera of chronic users of this combined contraceptive without affecting its pharmacodynamics.

Assessment of a new low-dose once-a-month injectable contraceptive

Norethisterone (NET) in combination with mestranol (ME), in a macrocrystalline aqueous suspension that provides sustained release of steroids, was assessed as a once-a-month injectable contraceptive in ten healthy women of reproductive age. The ovarian function was studied before and after the intramuscular administration of 12mg NET plus 1.2mg ME, delivered as crystals of 150 micron average size. Serial blood samples were taken throughout the injection intervals in all women to measure serum progesterone (P), estradiol (E2), and NET. The NET/ME preparation effectively inhibited ovulation in 23 out of the 25 injection intervals studied. The administration of this formulation induced in some women a small degree of follicular maturation not followed by luteal activity. The endometrial bleeding patterns after each injection showed a bleeding-free period of two to three weeks. The overall data demonstrate that the parenteral administration of a macrocrystalline steroid preparation of NET/ME can bring about a sustained release contraceptive system at a substantially lower dose than those currently employed in once-a-month injectable contraception.

Norethisterone-cholesterol eutectic mixture as an oral sustained-release hormonal preparation: bioequivalence study in humans

A solid dispersion of norethisterone and cholesterol (NET:CHOL; eutectic 1:4 w/w) was prepared by melting and rapid cooling. The fused material was then mixed with lactose as vehicle. Soft gelatin capsules were filled with 55 mg of the final mixture to give 0.35 mg of NET. One control formulation prepared with fused NET and lactose (NET:LAC) was capsuled with the same NET dosage, and one commercial tablet (Dianor, Syntex) with 0.35 mg NET were used as reference formulations. In a cross-over study, five female volunteers received, one month apart, in fasting state, each one of the three formulations. Blood samples were drawn at O,O.5,1,1.5,2,4,8,12,24 and 36 hours after dosing. Immunoreactive plasma NET was measured by RIA to assess pharmacokinetic parameters. The NET:CHOL formulation showed a greater area under the serum concentration-time curve, lower peak concentrations and a smaller release rate constant as compared to the reference preparations. It is concluded that the NET:CHOL eutectic mixture is a modified release dosage form and a sound approach in regulating the drug access rate to the body's central compartment.

The metabolism of 19-nor contraceptive progestins modulates their biological activity at the neuroendocrine level

In this communication, a series of studies from our laboratory dealing with the mechanism of action of 17 alpha-ethinyl derivatives of 19-nor testosterone are reviewed. The administration of norethisterone (NET) to long-term castrated female rats induces the nuclear translocation of pituitary estradiol receptors and is followed by some estrogenic-like effects at the hypothalamic-pituitary unit. It is established that an A-ring reduced metabolite of NET, the 3 beta,5 alpha-tetrahydro NET derivative, is responsible for the observed in vivo estrogenic effects of the parent compound. 3 beta,5 alpha-NET binds to the estrogen receptor and is efficient in inducing the pituitary estrogen-dependent progesterone receptor and in increasing the uterine weight in long-term castrated rats. Furthermore, administration of 3 beta,5 alpha-NET and the 5 alpha-reduced metabolite of NET (5 alpha-NET) are able to inhibit the release of gonadotropins in the castrated animal to a greater extent than NET. Moreover, pretreatment with tamoxifen, an estrogen binding site competitor, results in a significant diminution of the antigonadotropic potency of 3 beta,5 alpha-NET but not of the 5 alpha-NET, which is only inhibited by the administration of cyproterone acetate. These findings underline the importance of the metabolic rate of NET for the expression of its biological effects at the hypothalamic-pituitary unit.

Development of a low-dose monthly injectable contraceptive system: II. Pharmacokinetic and pharmacodynamic studies

A drug delivery system which provides a sustained release of norethindrone (NET) and mestranol (ME) for one month after a single intramuscular injection was assessed as a long-acting injectable contraceptive. The system is based upon well defined particle size crystals of the synthetic steroids maintained in suspension with saline solution. Eight healthy ovulating women volunteered for the study; they received a combination of 10 mg of NET plus 1 mg of ME in 1 ml of vehicle by intramuscular injection on day five of their menstrual cycle. Blood samples were drawn at 0, 1, 5, 10, 13, 17 and 21 days after drug administration. The immunoreactive serum levels of estradiol, progesterone, NET and ethinylestradiol were measured by specific radioimmunoassay procedures to assess ovarian function and the kinetic parameters of the synthetic steroids. This newly developed contraceptive system proved to be both effective, and long-lasting as well as devoid of side effects.

Pharmacodynamic assessment of dihydroxyprogesterone acetophenide plus estradiol enanthate as a monthly injectable contraceptive

The pharmacodynamics of the combination of dihydroxyprogesterone acetophenide (DHPA) and estradiol enanthate (E2-EN) following its intramuscular administration at two doses were studied in 16 healthy women of reproductive age. Subjects were randomly allocated in two groups: group I (n = 9) received the combination DHPA 150 mg + E2-EN 10 mg on three consecutive monthly injections, while group II (n = 7) received half-dose of the same formulation. Ovarian function and endometrial bleeding patterns were investigated in all participants for one pre-treatment cycle, three treatment intervals and two post-treatment cycles. The results disclosed that ovulation was inhibited for at least 30 days following DHPA/E2-EN administration in all participants from both groups. The circulating estradiol levels 30 days after last injection were slightly elevated as compared with those observed in normal early follicular phase. Return to ovulatory cycles was documented within 90 days after treatment. The length of the bleeding-free intervals during treatment was shortened in both groups, particularly in group II. No significant changes in HDL-cholesterol levels were observed throughout the study. It is envisaged however, that large modification of the formulation and additional long-term safety studies will be required prior to its recommendation.

A-ring reduction enhances the antigonadotropic potency of norethisterone

To assess whether structural modifications on the A-ring of norethisterone (NET) could modify its antigonadotropic potency, comparative studies using NET, 5 alpha-dihydro NET (5 alpha-NET) and its 3 beta,5 alpha and 3 alpha,5 alpha tetrahydro derivatives in castrated adult rats were undertaken. The antigonadotropic effect of these compounds was evaluated by measuring the serum and pituitary immunoreactive concentrations of LH and FSH following their chronic sc administration to animals depleted of progesterone receptors. The results demonstrated that 3 beta,5 alpha-NET and 5 alpha-dihydro-NET exhibited a significantly greater gonadotropic inhibiting activity as compared with that of their parent compound. The simultaneous administration of tamoxifen with 3 beta,5 alpha-NET resulted in a significant diminution of its antigonadotropic potency, particularly for LH. These data indicate that the potent antigonadotropic effect of 3 beta,5 alpha-NET metabolite was mediated via oestrogen receptors. The LH inhibitory activity of 5 alpha-dihydro-NET was not suppressed by the non-steroidal antioestrogen administration, thus suggesting that 5 alpha-NET might exert its effect via androgen receptors. The overall data were interpreted as demonstrating that metabolic conversion products of NET exhibit potent antigonadotropic effect. The data are consistent with an A-ring enhancement of the antigonadotropic potency of this synthetic progestin and open an alternate approach to the development of fertility regulating agents.

Synthesis and biological assessment of long-acting estradiol fatty acid esters in ovariectomized rats

Diesters of 17 beta-estradiol using palmitic acid (16:0) and oleic acid (18:1, cis-9-Octadecenoic acid) have been synthesized for potential evaluation as long-acting compounds. Female castrated rats were injected 1 mumol of estradiol dipalmitate and estradiol dioleate, using estradiol benzoate and estradiol enanthate as controls. Biological activity was determined by uterine wet weight and uterine diameter as well as on the suppression of serum anterior pituitary gonadotropins. A delayed absorption of estradiol was observed after administration of both diesters which was well correlated with the duration of biological effects. The data demonstrate that esterification with palmitic or oleic acids at 3 and 17 positions provides long-acting properties to 17 beta-estradiol, which could be applied in substitutive therapy and or in hormonal contraception.

Dysfunction of dopaminergic regulation of prolactin in patients with functioning and nonfunctioning pituitary adenomas and craniopharyngiomas

The response to domperidone (a dopamine blocking agent) of serum prolactin (PRL) levels was compared in 3 patients with amenorrhea-galactorrhea without evidence of a pituitary tumor, 23 patients with prolactinomas (10 cases with histologic confirmation), 7 patients with histologically verified large nonfunctioning pituitary adenomas with normal or moderately elevated basal PRL levels, and 6 patients with histologically verified craniopharyngiomas (3 with normal basal PRL levels and 3 with elevated PRL levels). The response was compared with that of 10 patients with postpartum hyperprolactinemia and 14 normal women. Ten milligrams of intravenous domperidone induced a rapid rise in PRL that was maximal at 30 to 45 minutes in normal, postpartum, and amenorrhea-galactorrhea patients who had no sign of tumor. In contrast, domperidone failed to induce significant changes in PRL in cases of prolactinoma, nonfunctioning pituitary adenomas, and craniopharyngioma with or without elevated basal PRL levels. The results suggest that dopaminergic control on PRL secretion was impaired in all tumor cases. The mechanisms of this abnormal dopaminergic control, however, may be different. Whereas dopamine control in cases of prolactinoma is altered at the level of pituitary dopamine receptors, alternative explanations must be found for those tumors with normal basal PRL levels and lack of response to domperidone.

Variations in serum lipids and lipoproteins throughout the menstrual cycle

One hundred fourteen women of reproductive age were included in a cross-sectional study with the aim of establishing the variations in serum lipids and lipoproteins during the menstrual cycle. Total cholesterol, triglycerides, and phospholipids were determined in whole serum and in the following lipoprotein fractions: very low-density lipoproteins (VLDL), low-density lipoproteins (LDL), and high-density lipoproteins, obtained by ultracentrifugation. A significant decrease was found in total cholesterol (P less than 0.05) and phospholipids (P less than 0.01) during the late luteal phase. The LDL cholesterol decreased during the luteal phase and VLDL cholesterol increased in the early and midluteal phases. The LDL phospholipids and VLDL triglycerides also showed a significant decrease during the luteal phase (P less than 0.01). The results of this investigation demonstrate major fluctuation in cholesterol, triglyceride, and phospholipid-lipoprotein composition during the menstrual cycle.

Return to ovulation following the use of long-acting injectable contraceptives: a comparative study

A comparative study was undertaken in twenty-four Mexican women who discontinued the use of depo-medroxyprogesterone acetate (DMPA) or norethisterone enanthate (NET-EN) to assess the time required for the return to menses and ovulation. All subjects were exposed to long-acting injectable contraceptives for at least one year, and were followed prospectively. Serum progesterone levels were determined weekly in all subjects beginning 3 months after the last progestogen injection. Mean time to return to ovulation occurred significantly earlier (p less than 0.001) after NET-EN (2.6 months) as compared with DMPA (5.5 months). No correlation between the return to ovarian function and the duration of steroid exposure was found. The overall data was interpreted as demonstrating a clear-cut difference between the two long-acting progestogens in terms of ovulation suppression.

Development of a low-dose monthly injectable contraceptive system: I. Choice of compounds, dose and administration route

A low-dose combined estrogen-progestogen sustained release system has been developed. The control of crystal size of the steroids produced sustained dissolution in vitro and in vivo. A dose-response experiment carried out in healthy women indicated that 10 mg of norethisterone (NET) with 1 mg of ethinylestradiol (EE2) when given by intramuscular injection maintained NET serum levels above 1 ng/ml for at least 25 days. The system is considered suitable for one month contraceptive protection.

Ovarian function following a single administration of depo-medroxyprogesterone acetate (DMPA) at different doses

The effects of a single administration of depo-medroxyprogesterone acetate (DMPA) at different doses upon ovarian function was studied in a group of healthy ovulating Mexican women. Single doses of DMPA of 25, 50, 100, and 150 mg were intramuscularly administered. Ovarian function was assessed by the measurement of the serum levels of 17 beta-estradiol and progesterone in blood samples drawn twice weekly for 6 months after DMPA administration. The results disclosed that ovulation was inhibited in all cases for at least 3 months following DMPA administration even at the lowest dose, whereas the return of luteal function exhibited a significant positive correlation with the dose of DMPA administered. As expected, follicular activity preceded that of luteal function in all subjects. A correspondence between serum medroxyprogesterone concentrations and ovarian function was found. The overall data indicated that the currently used contraceptive formulation (150 mg) is well above the effective pharmacologic range, and suggested that the dose can be substantially reduced without losing its anovulatory potency.

A rapid and sensitive radioimmunoassay for norethisterone

A direct radioimmunoassay for the measurement of norethisterone (NET) in unextracted serum samples was developed. The combined use of a highly specific unpurified antiserum and heat treatment of diluted serum samples obviated both extraction and chromatographic procedures. The direct NET assay fulfilled all the quality control parameters. When this assay was compared with other methods involving either solvent extraction and/or chromatographic purification procedures, no significant differences were observed. The overall results were interpreted as demonstrating that this simple, rapid and reliable NET assay can be used as a helpful tool in metabolic and pharmacokinetic studies of this contraceptive progestogen.

Predictive value of serum ferritin in anemia development after insertion of T Cu 220 intrauterine device

A one-year follow-up study in 30 healthy women was undertaken to study serum ferritin as well as other hematological parameters prior, six and twelve months after insertion of an intrauterine device, T Cu 220. Women were allocated into one of two groups according to the baseline ferritin serum levels; Group I abnormal ferritin and Group II normal ferritin levels. Other hematological parameters were normal and no iron supplement was given throughout the study. A direct relationship between low ferritin serum values (Group I), and anemia development was found. Seven out of 15 developed anemia, whereas only 2 out of 15 had anemia at twelve months in Group II with normal ferritin values. The overall data suggested that measurement of serum ferritin levels could be a useful tool to anticipate anemia development in women with intrauterine devices.

Solid-phase radioimmunoassay for norethisterone

Exposure of polystyrene tubes to solutions of glutaraldehyde was shown to provide a stable and consistent surface for immobilising an unpurified norethisterone-specific antiserum. Properties of the solid-phase antiserum were evaluated with respect to its application in developing a solid-phase radioimmunoassay for norethisterone. The assay proved to be sufficiently accurate, precise and sensitive for routine use. The technology is considered to be suited to automation.