The effects of different formulations of oral contraceptive agents on lipid and carbohydrate metabolism

BACKGROUND

Oral contraceptives can induce changes in lipid and carbohydrate metabolism similar to those associated with an increased risk of coronary heart disease, including increased serum triglyceride, low-density lipoprotein (LDL) cholesterol, and insulin levels and decreased high-density lipoprotein (HDL) cholesterol levels. In this study, we examined whether modification of the type or dose of progestin in oral-contraceptive preparations diminishes these changes.

METHODS

We measured plasma lipoprotein levels and performed oral glucose-tolerance tests in a cross section of 1060 women who took one of nine types of oral contraceptives for at least three months and 418 women who took none. Seven of the contraceptive formulations contained various doses and types of progestin: levonorgestrel in low (150 micrograms), high (250 micrograms), and triphasic (50 to 125 micrograms) doses; norethindrone in low (500 micrograms), high (1000 micrograms), and triphasic (500 to 1000 micrograms) doses; and a new progestin, desogestrel, in one dose (150 micrograms). All seven contained 30 to 40 micrograms of ethinyl estradiol. Two additional formulations contained progestin alone.

RESULTS

As compared with controls, women taking combination drugs did not have increased serum total cholesterol levels but did have increases of 13 to 75 percent in fasting triglyceride levels. Levels of LDL cholesterol were reduced by 14 percent in women taking the combination containing desogestrel and by 12 percent in those taking low-dose norethindrone. Levels of HDL cholesterol were lowered by 5 percent and 16 percent by the combinations containing low-dose and high-dose levonorgestrel, respectively; these decreases were due to reductions of 29 percent and 43 percent, respectively, in the levels of HDL subclass 2. The combination pill containing high-dose norethindrone did not affect HDL cholesterol levels, whereas that containing low-dose norethindrone increased HDL cholesterol levels by 10 percent. The desogestrel combination increased HDL cholesterol levels by 12 percent. Levels of apolipoproteins A-I, A-II, and B were generally increased by combination drugs. Depending on the dose and type of progestin, combination drugs were associated with plasma glucose levels on the glucose-tolerance test that were 43 to 61 percent higher than in controls, insulin responses 12 to 40 percent higher, and C-peptide responses 18 to 45 percent higher. Progestin-only formulations had only minor metabolic effects.

CONCLUSIONS

The appropriate dose and type of progestin may reduce the adverse effects of oral contraceptives on many metabolic markers of risk for coronary heart disease. Progestin-only formulations or combinations containing desogestrel or low-dose norethindrone were associated wtih the most favorable profiles.

Provision of no-cost, long-acting contraception and teenage pregnancy

BACKGROUND

The rate of teenage pregnancy in the United States is higher than in other developed nations. Teenage births result in substantial costs, including public assistance, health care costs, and income losses due to lower educational attainment and reduced earning potential.

METHODS

The Contraceptive CHOICE Project was a large prospective cohort study designed to promote the use of long-acting, reversible contraceptive (LARC) methods to reduce unintended pregnancy in the St. Louis region. Participants were educated about reversible contraception, with an emphasis on the benefits of LARC methods, were provided with their choice of reversible contraception at no cost, and were followed for 2 to 3 years. We analyzed pregnancy, birth, and induced-abortion rates among teenage girls and women 15 to 19 years of age in this cohort and compared them with those observed nationally among U.S. teens in the same age group.

RESULTS

Of the 1404 teenage girls and women enrolled in CHOICE, 72% chose an intrauterine device or implant (LARC methods); the remaining 28% chose another method. During the 2008-2013 period, the mean annual rates of pregnancy, birth, and abortion among CHOICE participants were 34.0, 19.4, and 9.7 per 1000 teens, respectively. In comparison, rates of pregnancy, birth, and abortion among sexually experienced U.S. teens in 2008 were 158.5, 94.0, and 41.5 per 1000, respectively.

CONCLUSIONS

Teenage girls and women who were provided contraception at no cost and educated about reversible contraception and the benefits of LARC methods had rates of pregnancy, birth, and abortion that were much lower than the national rates for sexually experienced teens. (Funded by the Susan Thompson Buffett Foundation and others.).

Levonorgestrel-releasing intrauterine device in the treatment of menorrhagia

In 20 women with menorrhagia (greater than 80 ml blood loss per menstrual period) a levonorgestrel-releasing intrauterine device (Lng-IUCD) was inserted. Menstrual blood loss (MBL) was measured in two consecutive cycles before the device was inserted and after 3, 6 and 12 months of use. MBL was significantly reduced after 3 months (86%) and after 12 months the reduction was 97%. There was a significant increase (P less than 0.001) in serum ferritin during the first year of Lng-IUCD use. The Lng-IUCD seems to be an important alternative to oral medication and to hysterectomy in the treatment of menorrhagia.

Health during prolonged use of levonorgestrel 20 micrograms/d and the copper TCu 380Ag intrauterine contraceptive devices: a multicenter study. International Committee for Contraception Research (ICCR)

OBJECTIVES

To measure and compare the incidence of adverse events during use of two medicated intrauterine devices (IUDs).

DESIGN

A multicenter prospective 7-year randomized study.

SETTING

Family planning clinics, primarily in developing countries.

SUBJECTS

Women age 18 to 38 years at admission, desiring contraception and without contraindications to IUDs.

MAIN OUTCOME MEASURES

Incidence of complaints, conditions, and rates of specific termination for each IUD.

METHODS

Subjects recorded menstrual events, and clinical staff registered all complaints and conditions found on examination at four first-year clinic visits and at semiannual visits thereafter. Difference in rates were analyzed by chi 2 statistics.

RESULTS

Annual pregnancy rates for each IUD averaged 0.2/100 women whereas upper genital tract infection occurred at rates of 0.6 to 0.7 per 100 years of use. The levonorgestrel-releasing IUD significantly decreased bleeding and spotting days in comparison with historical data for noncontraceptors and with the copper-medicated IUD. Dysmenorrhea, vaginitis, and myoma in women with the levonorgestrel IUD were markedly decreased in comparison with the experience of copper IUD users. Significantly higher rates of amenorrhea, delayed ovarian follicular atresia, skin and hair conditions, and headache were observed with the steroid IUD than with the copper-releasing IUD. Rates of reported adverse effects for either IUD were highest in the first 2 years of use and among women under age 25.

CONCLUSIONS

Long-term use of copper or levonorgestrel IUDs is characterized by very low rates of pregnancy and by a low and declining annual incidence of side effects, including pelvic infection and borderline anemia. The levonorgestrel-releasing IUD reduced the incidence of bleeding and, in the long term, of myoma and myoma-related surgery in comparison with the copper T IUD. Both IUDs proved highly acceptable and had few unanticipated side effects.

Endometrial morphology during long-term use of levonorgestrel-releasing intrauterine devices

Levonorgestrel-releasing intrauterine devices (IUD) were inserted in 92 women. Endometrial biopsies were taken between 3 months and 7 years after these insertions. Intrauterine release of levonorgestrel resulted in endometrial glandular atrophy and decidualized stroma. Inflammation and necrosis were also seen as local signs of IUD use. The biopsies were similar regardless of the duration of IUD use. Endometrial morphology returned to normal in biopsy specimens taken 1-3 months after IUD removal.

Prolonged intrauterine contraception: a seven-year randomized study of the levonorgestrel 20 mcg/day (LNg 20) and the Copper T380 Ag IUDS

A levonorgestrel-releasing IUD and the Copper T 380Ag IUD were in randomized comparison for seven years in five clinics. In two other clinics the randomized study was truncated at five years, but use of the Copper T continued. No pregnancies occurred to users of either device in years 6 and 7. Cumulative pregnancy rates were 1.1 per 100 at seven years for the steroid-releasing and 1.4 per 100 for the copper-releasing IUDs. Cumulative rates of PID did not differ between devices. Infection rates appeared to be lowest during the sixth and seventh years of the study. Termination attributable to amenorrhea was the principal contributor to differences in cumulative continuation rates between devices. At the five clinics that carried the comparative study to seven years, cumulative continuation rates were 24.9 per 100 for LNg20 IUD users and 29.4 per 100 for TCu 380Ag users. Women who used either method for periods of five to seven years experienced, on average, marked to mild increases in hemoglobin as compared with levels at admission. The Copper T380 family and the LNg20 IUDs represent the most effective reversible contraceptive methods yet studied in long-term randomized trials.

A comparison of flurbiprofen, tranexamic acid, and a levonorgestrel-releasing intrauterine contraceptive device in the treatment of idiopathic menorrhagia

Treatment with flurbiprofen (100 mg twice a day for 5 days), tranexamic acid (1.5 gm three times a day for 3 days and 1 gm twice a day for another 2 days), and an intrauterine contraceptive device releasing 20 micrograms levonorgestrel per day was compared in women with idiopathic menorrhagia. The menstrual blood loss during two control periods in 15 women subsequently treated with flurbiprofen and tranexamic acid was 295 +/- 52 ml and 203 +/- 25.2 ml in the 16 women later fitted with a levonorgestrel-releasing intrauterine contraceptive device. Menstrual blood loss was reduced by all three forms of treatment. The reduction in menstrual blood loss expressed as a percentage of the mean of two control cycles for each form of treatment was as follows: flurbiprofen, 20.7% +/- 9.9%; tranexamic acid, 44.4% +/- 8.3%; levonorgestrel-releasing intrauterine contraceptive device after 3 months, 81.6% +/- 4.5%; levonorgestrel-releasing intrauterine contraceptive device after 6 months, 88.0% +/- 3.1%; levonorgestrel-releasing intrauterine contraceptive device after 12 months, 95.8% +/- 1.2%. The reduction in menstrual blood loss achieved by the levonorgestrel-releasing intrauterine contraceptive device was greater than that recorded with flurbiprofen (p less than 0.001) and tranexamic acid (p less than 0.01), and was greater for tranexamic acid when compared with flurbiprofen (p less than 0.05). The levonorgestrel-releasing intrauterine contraceptive device was the only form of treatment to reduce mean menstrual blood loss below 80 ml per menstruation, the upper limit of normal menstrual blood loss.

Estrogen monotherapy and combined estrogen-progestogen replacement therapy attenuate aortic accumulation of cholesterol in ovariectomized cholesterol-fed rabbits

Cardiovascular disease is currently the leading cause of death among women in the United States. To investigate the effect of postmenopausal hormone therapy on atherogenesis, we studied 75 cholesterol-fed female rabbits for 19 wk. The rabbits were randomly assigned to five groups. Four groups underwent bilateral ovariectomy followed by treatment with either 17 beta-estradiol, 17 beta-estradiol plus norethisterone acetate, 17 beta-estradiol plus levonorgestrel, or placebo. The fifth group had a sham operation and received placebo. The hormone groups had only one-third of the aortic accumulation of cholesterol found in the placebo groups, a difference that was highly statistically significant (P less than 0.0001). No significant differences in aortic accumulation of cholesterol were found in the hormone groups. This indicates that estrogen attenuates atherogenesis in cholesterol-fed ovariectomized rabbits and that two commonly prescribed progestogens do not counteract the effect. The beneficial effect of estradiol could only partly be explained by its lowering effects on serum total cholesterol or VLDL cholesterol, which implies that estradiol possesses additional beneficial effects, possibly a direct action on the arterial wall.

Tissue concentrations of levonorgestrel in women using a levonorgestrel-releasing IUD

Thirteen women who were scheduled for hysterectomy volunteered for the study. Nine women had a levonorgestrel-releasing intrauterine contraceptive device inserted between 36 and 49 days prior to surgery and four women were on oral levonorgestrel treatment for 7 days prior to surgery. After the surgical removal of the uterus, samples of endometrial, myometrial, fallopian tube and fat tissue were obtained. Methods for measuring tissue concentrations of levonorgestrel were developed and the uptake of levonorgestrel by fat tissue in vitro was studied. The concentrations of levonorgestrel in myometrial, fallopian tube and fat tissue were all of the same order, of between 1 and 5 ng/g of wet weight of tissue, in both the intrauterine device group and the orally treated group. In the endometrium the levonorgestrel concentrations were many-fold higher in the intrauterine device group. The in vitro experiments showed a rapid uptake of levonorgestrel and an unsaturability of the fat tissue by the steroid at the concentrations used. The fat tissue concentrations of levonorgestrel correlated with the plasma concentrations.

Reductions in pregnancy rates in the USA with long-acting reversible contraception: a cluster randomised trial

BACKGROUND

Unintended pregnancy remains a serious public health challenge in the USA. We assessed the effects of an intervention to increase patients' access to long-acting reversible contraceptives (LARCs) on pregnancy rates.

METHODS

We did a cluster randomised trial in 40 reproductive health clinics across the USA in 2011-13. 20 clinics were randomly assigned to receive evidence-based training on providing counselling and insertion of intrauterine devices (IUDs) or progestin implants and 20 to provide standard care. Usual costs for contraception were maintained at all sites. We recruited women aged 18-25 years attending family planning or abortion care visits and not desiring pregnancy in the next 12 months. The primary outcome was selection of an IUD or implant at the clinic visit and secondary outcome was pregnancy within 12 months. We used generalised estimating equations for clustered data to measure the intervention effect on contraceptive selection, and used survival analysis to assess pregnancy rates.

FINDINGS

Of 1500 women enrolled, more at intervention than control sites reported receiving counselling on IUDs or implants (565 [71%] of 797 vs 271 [39%] of 693, odds ratio 3·8, 95% CI 2·8-5·2) and more selected LARCs during the clinic visit (224 [28%] vs 117 [17%], 1·9, 1·3-2·8). The pregnancy rate was lower in intervention group than in the control group after family planning visits (7·9 vs 15·4 per 100 person-years), but not after abortion visits (26·5 vs 22·3 per 100 person-years). We found a significant intervention effect on pregnancy rates in women attending family planning visits (hazard ratio 0·54, 95% CI 0·34-0·85).

INTERPRETATION

The pregnancy rate can be reduced by provision of counselling on long-term reversible contraception and access to devices during family planning counselling visits.

FUNDING

William and Flora Hewlett Foundation.

Long-term contraception with the levonorgestrel 20 mcg/day (LNg 20) and the copper T 380Ag intrauterine devices: a five-year randomized study

An intrauterine device, releasing approximately 20 micrograms/day of levonorgestrel (LNg 20), used by 1124 women, was studied in a randomized trial of five years duration in comparison with the Copper T, model TCu 380Agm in 1121 women. At five years, the gross cumulative pregnancy rate of 1.1 +/- 0.5 per 100 among users of the LNg 20 devices was not significantly different from the rate of 1.4 +/- 0.4 per 100 experienced by users of the Copper T 380Ag. The steroid-releasing IUD had significantly higher termination rates for expulsion and amenorrhea, a significantly lower termination rate for other menstrual problems and pain, and a lower continuation rate. The five-year continuation rate among women using the TCu 380Ag was 40.6 per 100 as compared with that of 33.0 per 100 among women randomized to the LNg 20 device (P less than .001). Terminations attributed to amenorrhea with the LNg device primarily account for differences in continuation. These two intrauterine devices are the most effective long-term, reversible IUDs yet reported in the literature. No other contraceptive methods have exhibited such low long-term pregnancy rates in randomized comparative trials.

Levonorgestrel-releasing intrauterine device

An intrauterine contraceptive device releasing 20 micrograms levonorgestrel daily has been studied for 15 years. The international clinical experience covers over 8000 woman years. Main characteristics of the levonorgestrel-releasing intrauterine device are its great effectiveness in preventing unplanned pregnancies and a reduction in menstrual bleeding and pain as well as a low infection rate.

Protective effect of intrauterine release of levonorgestrel on pelvic infection: three years' comparative experience of levonorgestrel- and copper-releasing intrauterine devices

A randomized, multicenter comparison of two intrauterine contraceptive devices (IUDs) was carried out. Nine hundred thirty-seven women were fitted with a copper-releasing IUD, the Nova-T, and 1821 women with an IUD that releases 20 micrograms of levonorgestrel daily. After 36 months, the cumulative gross rates of amenorrhea and hormonal side effects were significantly higher in the levonorgestrel-IUD users. The cumulative 36-month gross pregnancy rate was 3.7 for the Nova-T and 0.3 for the levonorgestrel IUD (P less than .001), demonstrating the levonorgestrel IUD's high contraceptive efficacy. For the first time, a protective effect of the levonorgestrel IUD against pelvic inflammatory disease as compared with the Nova-T was seen statistically. The cumulative 36-month gross rate of pelvic inflammatory disease was 2.0 in Nova-T- and 0.5 in levonorgestrel-IUD users (P less than .013). This significantly lowered incidence of pelvic inflammatory disease may help to solve one of the major concerns associated with intrauterine contraception.

Coagulation effects of oral contraception

In Europe and North America, estrogen/progestogen oral contraception has been associated with an increase in venous thromboembolism, myocardial infarction, and stroke. These hazards are found mainly in smokers and in women over the age of 35. Venous thromboembolism appears to correlate with the estrogen dosage, and the arterial complications with both the estrogen and progestogen components. Blood coagulation and vascular thrombosis are intimately related. Estrogen/progestogen oral contraception affects blood clotting by increasing plasma fibrinogen and the activity of coagulation factors, especially factors VII and X; antithrombin III, the inhibitor of coagulation, is usually decreased. Platelet activity is also enhanced with acceleration of aggregation. These changes create a state of hypercoagulability that, to a large extent, appears to be counterbalanced by increased fibrinolytic activity. Studies of the oral contraceptives in current use show that the coagulation effects depend on the dosage of estrogen and the type of progestogen used in combination. Current research is aimed at finding the estrogen/progestogen formulations that induce the least changes in the coagulation system and other physiologic processes. In this respect, the new low-dose formulations are a major step forward and should reduce the risk of vascular thrombotic complications.

The interaction of phenytoin and carbamazepine with combined oral contraceptive steroids

Patients taking oral contraceptive steroids (OCS) are known to suffer contraceptive failure while taking anticonvulsants such as phenobarbitone, phenytoin and carbamazepine. We have studied the single dose kinetics of ethinyloestradiol (EE2); 50 micrograms, and levonorgestrel (Ng); 250 micrograms in groups of women before and 8-12 weeks after starting therapy with phenytoin (n = 6) and carbamazepine (n = 4). The area under the plasma concentration-time curve (AUC) was measured over a 24 h period for each steroid and significant reductions were seen with both anticonvulsants. Phenytoin reduced the AUC for EE2 from 806 +/- 50 (mean +/- s.d.) to 411 +/- 132 pg ml-1 h (P less than 0.05) and for Ng from 33.6 +/- 7.8 to 19.5 +/- 3.8 ng ml-1 h (P less than 0.05). Carbamazepine reduced the AUC for EE2 from 1163 +/- 466 to 672 +/- 211 pg ml-1 h (P less than 0.05) and for Ng from 22.9 +/- 9.4 to 13.8 +/- 5.8 ng ml-1 h (P less than 0.05). These changes are compatible with the known enzyme inducing effects of phenytoin and carbamazepine. Patients taking these anticonvulsants will need to be given increased doses of OCS (equivalent to 50-100 micrograms EE2 daily) to achieve adequate contraceptive effects.

Mechanisms of action of intrauterine devices: update and estimation of postfertilization effects

There are many potential mechanisms of action for the intrauterine device (IUD), which vary by type of IUD (inert, copper, or hormonal). This paper reviews the evidence for each potential mechanism of action. On the basis of available data for fertilization rates and clinical pregnancy rates, the relative contribution of mechanisms acting before or after fertilization were quantitatively estimated. These estimates indicate that, although prefertilization effects are more prominent for the copper IUD, both prefertilization and postfertilization mechanisms of action contribute significantly to the effectiveness of all types of intrauterine devices.

Effective contraception with the levonorgestrel-releasing intrauterine device: 12-month report of a European multicenter study

The use-effectiveness of an intrauterine contraceptive device releasing 20 mcg of levonorgestrel daily (Lng-IUD), and of a Nova T copper-releasing IUD, were studied in a randomized, comparative multicenter trial. The Lng-IUD was inserted in 1821, and the Nova T in 937 women. The 12-month net pregnancy rate with the Lng-IUD (0.1 per hundred women) was significantly lower than that with the Nova T (0.9 per hundred). Removal rates for menstrual problems and/or pain were similar for the two methods (net rates 7.5 and 8.7, respectively). The 12-month continuation rates were 82.2 for the Nova T and 79.7 for the Lng-IUD. The reduction of the bleeding led to oligomenorrhea and amenorrhea in users of the Lng-IUD; the removal rate for these reasons was 1.4. The removal rate for hormonal side effects with the Lng-IUD was 2.4. Blood hemoglobin concentrations increased among users of the Lng-IUD and decreased among users of the Nova T. The results show that the Lng-IUD was a highly effective contraceptive method which reduced menstrual bleeding. It is a promising alternative for women desiring a highly effective method for long-term use.

Serum steroid binding protein concentrations, distribution of progestogens, and bioavailability of testosterone during treatment with contraceptives containing desogestrel or levonorgestrel

The oral administration of 150 micrograms desogestrel and 30 micrograms ethinyl estradiol (EE2) increases (P less than 0.001) serum concentrations of sex-hormone-binding globulin (SHBG) and corticosteroid-binding globulin (CBG), whereas treatment with 150 micrograms levonorgestrel and 30 micrograms EE2 only increases serum CBG concentrations. No changes in serum albumin concentrations occurred during or after treatment with either preparation, and increases in SHBG and CBG returned to the pretreatment values 1 month after treatment ceased. The serum distribution of levonorgestrel was unchanged during treatment, whereas the increase in serum SHBG concentrations after treatment with the preparation containing desogestrel decreased (P less than 0.001) the percentage of non-protein-bound 3-keto- desogestrel and the percentage of albumin-bound 3-keto- desogestrel but increased (P less than 0.001) the SHBG-bound fraction. Oral contraceptives containing either progestogen decrease the mean serum non-protein-bound testosterone concentrations, especially during treatment with desogestrel (P less than 0.001), and desogestrel may therefore by the more appropriate progestogen for the treatment of women prone to androgenic side effects.

Five years' experience with levonorgestrel-releasing IUDs

Two levonorgestrel-releasing IUDs and a copper-releasing IUD of the same shape were studied in a randomized comparative study over five years. The levonorgestrel-releasing IUDs released 20 micrograms or 30 micrograms per day. The Pearl index during the 10,600 woman-months of LNG-IUD use was 0.11. The control device releasing copper had a Pearl index of 1.6. The amount and duration of menstrual bleeding was greatly reduced, leading to a high incidence of oligo- or amenorrhea. The continuation rate in this pioneer trial was 53 per 100 users for the levonorgestrel-releasing IUD (LNG-IUDs) and 50 per 100 users for the copper-releasing IUD (Nova T). The removal rates for reasons other than amenorrhea were not significantly different. Discontinuation because of amenorrhea occurred during the first two years, the cumulative termination rate for this reason was 11.6 per 100 users at five years. The LNG-IUDs removed for investigation after five years of use revealed that the devices contained about 40 percent of the original load. The effective lifespan of the device has been demonstrated by this study to be five years; the residual steroid gives an additional safety period of two more years. The LNG-IUD is a highly effective reversible contraceptive method, which strongly reduced the amount and duration of bleeding. During the first two months there is scanty but frequent spotting which, like the high incidence of oligo- and/or amenorrhea, requires counselling of health personnel and women using LNG-IUDs.

Complex mixtures of dissolved pesticides show potential aquatic toxicity in a synoptic study of Midwestern U.S. streams

Aquatic organisms in streams are exposed to pesticide mixtures that vary in composition over time in response to changes in flow conditions, pesticide inputs to the stream, and pesticide fate and degradation within the stream. To characterize mixtures of dissolved-phase pesticides and degradates in Midwestern streams, a synoptic study was conducted at 100 streams during May-August 2013. In weekly water samples, 94 pesticides and 89 degradates were detected, with a median of 25 compounds detected per sample and 54 detected per site. In a screening-level assessment using aquatic-life benchmarks and the Pesticide Toxicity Index (PTI), potential effects on fish were unlikely in most streams. For invertebrates, potential chronic toxicity was predicted in 53% of streams, punctuated in 12% of streams by acutely toxic exposures. For aquatic plants, acute but likely reversible effects on biomass were predicted in 75% of streams, with potential longer-term effects on plant communities in 9% of streams. Relatively few pesticides in water-atrazine, acetochlor, metolachlor, imidacloprid, fipronil, organophosphate insecticides, and carbendazim-were predicted to be major contributors to potential toxicity. Agricultural streams had the highest potential for effects on plants, especially in May-June, corresponding to high spring-flush herbicide concentrations. Urban streams had higher detection frequencies and concentrations of insecticides and most fungicides than in agricultural streams, and higher potential for invertebrate toxicity, which peaked during July-August. Toxicity-screening predictions for invertebrates were supported by quantile regressions showing significant associations for the Benthic Invertebrate-PTI and imidacloprid concentrations with invertebrate community metrics for MSQA streams, and by mesocosm toxicity testing with imidacloprid showing effects on invertebrate communities at environmentally relevant concentrations. This study documents the most complex pesticide mixtures yet reported in discrete water samples in the U.S. and, using multiple lines of evidence, predicts that pesticides were potentially toxic to nontarget aquatic life in about half of the sampled streams.

Contraceptive steroids and coronary artery atherosclerosis in cynomolgus macaques

The influence of two types of steroidal contraception on the extent of coronary, aortic, carotid, and iliaco-femoral atherosclerosis was assessed in 57 cynomolgus macaques with moderate diet-induced hyperlipoproteinemia. Thirteen animals were treated with an intravaginal ring that released 17 beta-estradiol and levonorgestrel. Fifteen females were treated with an oral contraceptive (OC) composed of ethinyl estradiol and norgestrel. Fifteen females received placebo vaginal rings, and 14 males were untreated. The contraceptive treatments resulted in similar large reductions in plasma high-density lipoprotein (HDL) cholesterol concentrations. Neither treatment influenced the prevalence of coronary artery atherosclerosis. However, treatment with the contraceptive vaginal ring was associated with increased extent of coronary artery atherosclerosis (plaque size) relative to untreated females, whereas treatment with the OC was not. The contrasting effects of the two treatments could not be explained by differences in total plasma cholesterol, HDL cholesterol, or blood pressure. The results suggest that the greater estrogenic influence associated with the ethinyl estradiol-containing OC resulted in inhibition of coronary artery atherosclerosis despite a pronounced progestin-induced lowering of plasma HDL cholesterol concentration and, further, that hormonal balance may have a marked influence on the relationship between plasma lipids and atherogenesis.

Selectivity in progesterone and androgen receptor binding of progestagens used in oral contraceptives

The relative binding affinities (RBAs) of four progestational compounds (norethisterone, levonorgestrel, 3-keto-desogestrel and gestodene) for the human progesterone and androgen receptors were measured in MCF-7 cytosol and intact MCF-7 cells. For the binding to the progesterone receptor, both Org 2058 and Org 3236 (or 3-keto-desogestrel) were used as labelled ligands. The following ranking (low to high) for the RBA of the nuclear (intact cells) progesterone receptor irrespective of the ligand used is found: norethisterone much less than levonorgestrel less than 3-keto-destogestrel less than gestodene. The difference between the various progestagens is significant with the exception of that between 3-keto-desogestrel and gestodene, when Org 2058 is used as ligand. For the cytosolic progesterone receptor, the same order is found with the exception that similar RBAs are found for gestodene and 3-keto-desogestrel. The four progestagens clearly differ with respect to binding to the androgen receptor using dihydrotestosterone as labelled ligand in intact cells; the ranking (low to high) is: norethisterone less than 3 keto-desogestrel less than levonorgestrel and gestodene. The difference between 3-keto-desogestrel and levonorgestrel or gestodene is significant. The selectivity indices (ratio of the mean RBA for the progesterone receptor to that of androgen receptor) in intact cells are significantly higher for 3-keto-desogestrel and gestodene than for levonorgestrel and norethisterone. From these results we conclude that the introduction of the 18-methyl in norethisterone (levonorgestel) increases both the binding to the progesterone and androgen receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Ovarian function during use of a levonorgestrel-releasing IUD

Ovarian function was studied for two complete menstrual cycles in 9 regularly menstruating women and for 8 weeks in three amenorrhoeic women who had used levonorgestrel-releasing IUDs (LNG-IUD) for more than four years. Nine patients using copper IUDs (Nova-T) were studied for two complete menstrual cycles as controls. According to progesterone levels, 15/17 cycles in women using LNG-IUDs were ovulatory, whereas only 8/17 cycles showed normal follicular growth and rupture as judged by ultrasound. In ovulatory cycles, the peak progesterone levels were lower than in the controls. The preovulatory estradiol and LH peak levels were also lower than in control subjects. SHBG levels were lower in LNG-IUD users than in copper IUD users. It is concluded that, although the dose of levonorgestrel released from the IUD is very low, it probably exerts an effect on the gonadotrophin secretion, which disturbs follicular development in many of the women studied, which in addition to the local effect on the endometrium, contributes to its high contraceptive efficacy.

Metabolism of levonorgestrel, norethindrone, and structurally related contraceptive steroids

There is limited information on the metabolism of levonorgestrel, norethindrone and structurally related contraceptive steroids. Both levonorgestrel and norethindrone undergo extensive reduction of the alpha, beta-unsaturated ketone in ring A. Levonorgestrel also undergoes hydroxylation at carbons 2 and 16. The metabolites of both compounds circulate predominantly as sulfates. In urine, levonorgestrel metabolites are found primarily in the glucuronide form, whereas norethindrone metabolites are present in approximately equal amounts as sulfates and glucuronides. Of the progestogens structurally related to norethindrone, norethindrone acetate, ethynodiol diacetate, norethindrone enanthate, and perhaps lynestrenol, undergo rapid hydrolysis and are converted to the parent compound and its metabolites. There is no convincing evidence that norethynodrel is converted to norethindrone. Of the progestogens structurally related to levonorgestrel, it appears that neither desogestrel nor gestodene are transformed to the parent compound. However, there is evidence that norgestimate can be, at least partly, converted to levonorgestrel. Further studies on the metabolism of these progestogens are required before we can understand their mechanism of action.