Insulin sensitivity is decreased in normal women by doses of ethinyl estradiol used in oral contraceptives

OBJECTIVE

We determined the independent effects of various doses of ethinyl estradiol used in oral contraceptives or norethindrone acetate, as well as their combination, on insulin sensitivity in normal women.

STUDY DESIGN

Thirty-three normal ovulatory female volunteers were recruited for this study. Insulin tolerance tests were performed after carbohydrate loading to determine the kinetic disappearance of glucose and insulin. After initial testing the women were randomized into four groups: ethinyl estradiol 20 micrograms, 35 micrograms, and 50 micrograms and norethindrone 1 mg. Insulin tolerance tests were repeated after 1 month of treatment and again after a second month, when all ethinyl estradiol groups received the addition of norethindrone 1 mg to their doses of ethinyl estradiol. Plasma glucose and insulin were measured, and insulin sensitivity (K(itt) glucose) and the disappearance of insulin (K(itt) insulin) were calculated.

RESULTS

All groups were comparable at baseline, and no significant changes in fasting glucose and insulin were evident with treatment. After ingestion of 50 micrograms ethinyl estradiol the K(itt) glucose value decreased significantly (p < 0.03) and ingestion of 20 micrograms and 35 micrograms showed individual changes, but as groups the changes were not statistically significant. All ethinyl estradiol groups combined had a significant decrease in K(itt) glucose (p < 0.01). Norethindrone 1 mg alone did not change K(itt) glucose values, and after the addition of norethindrone to ethinyl estradiol, K(itt) glucose values normalized. K(itt) insulin values were also lower with treatment but were lower with ethinyl estradiol plus norethindrone compared with ethinyl estradiol alone (p < 0.04), suggesting an attenuation of insulin clearance with the progestin.

CONCLUSION

Ethinyl estradiol alone decreases insulin sensitivity, and this may occur at lower doses, but norethindrone 1 mg does not appear to do so. However, progestins may alter insulin clearance.

The varying effects of progestins on lipid levels and cardiovascular disease

A recent study at George Washington University Lipid Research Clinic compared three oral contraceptives containing different progestins and found that increases in total cholesterol, triglycerides, and apoprotein. All were not progestin related. Other effects, however, were apparently dependent on the type of progestin, with the androgenically potent agent dl-norgestrel causing dramatic increases in low-density lipoprotein (LDL)-cholesterol and the ratio of low-density to high-density lipoprotein (HDL) and decreases in HDL, particularly HDL2, and apoprotein Al. Reductions in HDL2 and increases in the LDL/HDL ratio are strongly associated with the development of atherosclerosis. In a study of postmenopausal women receiving hormone replacement therapy, estrogen alone was compared with estrogen plus dl-norgestrel. In contrast to the findings of the previous study, norgestrel lowered LDL and produced less substantial decreases in HDL and HDL2. Thus, although an antiestrogenic effect was evident, it cannot be assumed that the changes associated with progestin-containing oral contraceptives will automatically occur when lower doses of progestin are used in hormone replacement therapy.

[A clinical report of norethisterone-3-oxime-acetate vacation pill]

This paper reported the clinical application of Norethisterone-Oxime-Acetate used as a "vacation" pill. The result indicated that pregnancy could be prevented in women who received this drug orally when they themselves or their husband came home on leave. A dose of 2 mg was administered for women on the 1st day when the couples live together, then followed by 1 mg daily successively and an additional pill was given on the morning next to the end of the leave. A high efficacy of 99.75% in terms of cycles proved in 604 women with 825 treated cycles of 604 women. The changes in menstrual cycles, the duration of menstrual bleeding and the amount of flow after treatment were very slight. The incidence of the intermenstrual bleeding and withdrawal bleeding were 2.16%. The author's observation showed that Norethisterone-oxime-Acetate is an active contraceptive pill and possesses the advantages of not only high efficacy, low side effect, but also convenience in use.

Norethisterone acetate and ethinylestradiol in early human pregnancy

In a double-blind randomized trial, 25 women (8-9 weeks pregnant) received 20 mg norethisterone acetate (NET-AC) and 0.04 mg ethinylestradiol (EE2), 25 women receiving placebo. The patients were followed by ultrasound and the products at curettage studied macroscopically and microscopically. In an open trial, ten patients (5-9 weeks pregnant) received NET-AC + EE2, 11 serving as controls. The concentrations of plasma progesterone, estradiol-17 beta, 17 alpha-hydroxyprogesterone, norethisterone, and FSH were followed. The frequency of intrauterine hemorrhage in early pregnancy was not affected by NET-AC + EE2. Ultrasound was not reliable when studying the occurrence of decidual hemorrhages during early pregnancy. The pharmacokinetics and bioavailability of NET remain unchanged during early pregnancy. The treatment with NET-AC + EE2 had no effect on the heights and the time courses of the mean plasma values of progesterone, estradiol-17 beta, 17 alpha-hydroxyprogesterone, and FSH. No differences were found between treated and nontreated patients in the pathology of the placenta or decidua as determined by both macroscopic and microscopic examinations. The hypothesis of Papp and Gardo, that decidual hemorrhages may be induced in early pregnancy as a consequence of a "withdrawal effect" of hormonal pregnancy tests, is not supported by the results of this investigation.

Lipid metabolic studies in oophorectomised women: effects on serum lipids and lipoproteins of three synthetic progestogens

Norethisterone acetate, medroxyprogesterone acetate and levonorgestrel were administered to oophorectomised women to evaluate the effects they have on lipid metabolism. Blood samples were drawn after a 3 wk period without hormone therapy and after 3 wk on each progestogen. Serum and lipoprotein lipids were followed and an oral glucose tolerance test with blood glucose and plasma insulin determinations were performed. The nortestosterone derivatives, norethisterone acetate and levonorgestrel, decreased high density lipoprotein cholesterol as well as alpha-lipoproteincholesterol, while the 17-hydroxyprogesterone derivative medroxyprogesterone acetate did not. Norethisterone acetate and medroxyprogesterone acetate impaired glucose tolerance. A difference between nortestosterone derivatives and 17-hydroxyprogesterone derivatives having an effect on high density lipoproteins is suggested.

Plasma protein binding of norethisterone

Norethisterone (NET) is transported in the blood stream bound to plasma proteins. It is generally believed that only the part of the hormone that is not bound to plasma proteins can exert biological activity. NET binds to albumin and, like other 19-nortestosterone derived progestins, it also binds to sex hormone binding globulin (SHBG). The binding of NET to SHBG was studied in five women during a 21-day treatment cycle with an oral contraceptive containing 3 mg NET-acetate and 50 microgram ethinylestradiol. The total and SHBG-bound concentrations of NET increased in parallel with SHBG during treatment. The fraction not bound to SHBG and the free fraction of NET increased proportionately less, indicating that the total concentrations of NET measured by radioimmunoassay only in part reflect the biologically active fraction of the steroid.

The influence of oral contraceptives on the composition of bile

The increased risk of cholelithiasis during intake of oral contraceptives may be due to estrogen-induced saturation of the bile with cholesterol. In a randomized, prospective, crossed-over double-blind study 20 healthy women after roentgenological exclusion of gall-stones received either 1.0 mg of norethindrone acetate and 50 microgram ethinyl estradiol daily - as usual in oral contraception - for 21 days with 7 days of placebo treatment in each cycle or one fifth of this hormone dose in form of a continuous daily medication. After a 4 month's treatment the medication form was crossed-over. At the beginning of the study, before the cross-over and after the study bile was collected by duodenal intubation after a 12-h fast and the lithogenic index as a measure for cholesterol saturation of the bile was determined. No correlation between the dose and the lithogenic index was demonstrated, neither in 15 women, who had used oral contraceptives before the study nor in five women without any previous hormonal contraceptives.

Pharmacokinetics of norethindrone acetate in women after the insertion of a single subdermal implant releasing norethindrone acetate

The metabolic clearance rate (MCR) of norethindrone acetate (NETA) and norethindrone (NET) levels in plasma were studied after an iv injection of [3H]NETA in three women before and at 1 week, 1, 2 and 6 months following the insertion of a single silastic subdermal implant releasing microquantities of NETA. No significant change in the MCR of NETA was observed at 1 week (459 +/- 72 1/day), 1 month (489 +/- 113 1/day) and 2 months (522 +/- 144 1/day) compared with that of control (525 +/- 108 1/day). However, MCR of NETA showed significant increase in women exposed to continuous presence of NETA for a period of 6 months (608 +/- 121 1/day; P less than 0.025). NETA was rapidly and extensively metabolized into NET. At 1 week, 1, 2 and 6 months of study, NET was observed to be present in higher amounts compared with NETA. The production rate (PR) of progesterone decreased significantly at 2 and 6 months of NETA implant insertion compared with the PR before the insertion of implant.

In vivo production of nucleolar channel system in human endocervical secretory cells

Human endocervical mucosa taken from the proliferative, ovulatory and secretory phases of the menstrual cycle in normal fertile women and those after administration of norethiosterone acetate for contraception was studied by electron microscopy. The fine structure of secretory cells, with special reference to the secretory granules and nucleolar differentiation, has been described and discussed. The 'nucleolar channel system' has been observed for the first time in the endocervical nucleolus in the proliferative phase of the menstrual cycle. On the basis of results of antifertilization effects of norethiosterone acetate, it has been suggested that the 'nucleolar channel system' may be a cell organelle prerequisite for the secretion of endocervical mucosa in fertility.

[The effect of norethisterone acetate and 17 alpha-cyanomethyl-estradiol-3-methyl ether on the serum lipid levels]

Noraethisterone acetate in a dosage of 5 mg/day led to a decrease of the triglyceride and beta-lipoprotein level in the blood serum in postclimacteric patients. In females with hypercholesterolamias by 17 alpha-cyanomethyl-oestra-diol-3-methylether a decrease of cholesterol by 12.9% was achieved. The sexualspecific properties of these connections forbid, however, a long-term therapy of hyperlipoproteinaemias.

Studies on ethanol and oral contraceptives: feasibility of a hepatic-gonadal link

Adult male and female rats were subjected to gonadectomy by means of surgical removal of the gonads. In the male, castration resulted in a significant decrease in both body and liver weights compared to intact controls, which persisted for at least 3 weeks. Conversely, ovariectomy was associated with a significant enhancement in both growth rate and liver weight from intact controls. Castration of male rats resulted in induction of hepatic L-ADH (cytosolic alcohol dehydrogenase) and L-ALDH (cytosolic aldehyde dehydrogenase) as contrasted with inhibition of mitochondrial ALDH which was evident in the enzyme with the apparent high Km. Kinetic studies indicate that there was an increase in apparent Km of L-ADH, and hence reduced affinity to hepatic metabolism of ethanol as a consequence of castration in the male rat. This is compared with few changes occurring in the apparent Km value of L-ALDH. Ovariectomy did not alter endogenous L-ADH or L-ALDH. Short-term administration of a synthetic estrogenic steroid ethinyl estradiol, inhibited liver mitochondrial ALDH in the intact female rat but not in the ovariectomized female. Short-term administration of the same dose of an androgen, testosterone, did not alter specific activities of the liver enzymes measured in the intact or in the castrated male rat. Administration of both components of OCs (oral contraceptives) combined or the estrogen alone in behavioral experiments profoundly reduced ethanol drinking by voluntary intake of diluted ethanol solution by the intact female rat. These results suggest a hepatic-gonadal link may exist and that a toxic interaction between the OCs and alcohol drinking is definitely possible.

Comparative studies of the ethynyl estrogens used in oral contraceptives. VII. Effects with and without progestational agents on ultracentrifugally fractionated plasma lipoproteins in humans, baboons, and beagles

Ethynyestradiol and mestranol, in doses ranging from 50 to 100 microgram/day, were given to women in 21-day cycles; baboons and beagle dogs received 1 and 4 microgram/kg/day in a similar regimen. After a number of such cycles, megestrol acetate, norethindrone acetate, or dl-norgestrel was given concomitantly. Protein, cholesterol, triglyceride, and phospholipid levels were determined in total plasma and in ultracentrifugally separated lipoprotein fractions. Over the dosage range studied, the effects of the two kinds of estrogen were indistinguishable. Except for human total plasma triglyceride, no dose-related differences were observed. The lowering of serum protein and the increase in cholesterol induced by estrogen were more pronounced in baboons and beagles than in human subjects. The cholesterol-depressing effect of progestational compounds observed in humans was very pronounced in baboons but absent in beagles. In all three species, estrogen increased the lipoprotein fraction cholesterol, except for human low-density lipoprotein cholesterol, which was decreased. Human plasma triglyceride and phospholipid increased on estrogen administration and were decreased by the progestins; in the two animal species, triglyceride is normally very low and the estrogen-induced changes were negligible; the phospholipid rose with estrogen but was unaffected by progestins. In sum, the two animal species show many similarities to, as well as important differences from, the human response of plasma lipids to various contraceptive steroids.

Comparative studies of the ethynyl estrogens used in oral contraceptives. VI. Effects with and without progestational agents on carbohydrate metabolism in humans, baboons, and beagles

Human subjects, baboons, and beagles were given cyclic regimens of ethynylestradiol or mestranol; after a number of such cycles, concurrent administration of norethindrone acetate, dl-norgestrel, or megestrol acetate was introduced for a similar number of cycles. Carbohydrate tolerance was evaluated by oral glucose tolerance testing in the human subjects and by intravenous glucose tolerance testing in the baboons and beagles. In the human subjects, neither mestranol nor ethynylestradiol at daily doses of 50 to 100 microgram/day produced any effect on fasting glucose levels or on glucose tolerance even after six cycles of treatment. The addition of the progestational compounds also had no effect on these two variables. In baboons, ethynylestradiol and mestranol were bioequivalent and produced a dose-related decrease in the glucose disposal rate. All three progestational agents counteracted this effect in a comparable manner. In beagles, on the other hand, estrogens produced an increase in the glucose disposal rate, and the addition of progestational agents produced an initial fall and a subsequent return to pretreatment levels.

Serum lipids and lipoproteins during treatment with oral contraceptives containing natural and synthetic oestrogens. A controlled double-blind investigation

Increases in serum triglycerides, cholesterol and pre-β- and β-lipoproteins have been considered as significant pathogenic factors regarding the possible thrombotic side-effect of treatment with oral contraceptives of the combined type containing synthetic oestrogen. With the purpose of investigating the influence of natural oestrogen (oestradiol-17β + oestriol/norethisterone acetate) versus synthetic oestrogen (ethinyloestradiol/norethisterone acetate) on serum lipids and lipoproteins in young women compared to independent and individual controls, as controlled double-blind investigation was performed in 33 women in a total material and 18 women in a selected group. The significant changes were as follows: quantitative increases in serum triglycerides (P < 0.001) and β-lipoproteins (P < 0.01) during treatment with synthetic oestrogen, while in contrast no such change was observed in subjects on natural oestrogen, which was found to decrease serum cholesterol (P < 0.05), phospholipids (P < 0.05) and α-lipoprotein (P < 0.05). Quantitative estimation of serum lipoproteins was found to be more valuable than the relative estimation by electrophoresis. It is concluded that oral contraceptives containing natural oestrogens induce less significant and, qualitatively, more benign changes in serum lipids and lipoproteins than preparations containing synthetic oestrogen do.