Studies on the role of intestinal bacteria in metabolism of synthetic and natural steroid hormones

Administration of antimicrobial agents to subjects taking oral contraceptives has been reported to lead to contraceptive failure and subsequent pregnancy. In women taking oral contraceptives antimicrobial agents could have an effect on both endogenous hormone levels and on the metabolism of the exogenously administered steroids. To investigate these possibilities, antimicrobial agents were administered for short periods to normal women taking various steroid drugs: Megestrol acetate (MA), medroxyprogesterone acetate (MPA), norethisterone (NET), a combination of NET and ethinylestradiol (EE) or a combination of lynestrenol and EE. During ampicillin administration the 24-h morning plasma concentrations of MA, MPA and NET were increased compared to the control values. In the MA and MPA experiments the afternoon values were determined and also found to be increased. In the subjects taking oral contraceptives plasma EE concentration showed a tendency to decrease during ampicillin administration on the third, fourth or fifth morning of ampicillin administration, but was never lower than the pretreatment values. In other experiments plasma estrone (E1) and estradiol (E2), urinary total E1, E2 and estriol (E3) and fecal unconjugated and conjugated E1, E2 or E3 were determined by RIA before, during and after administration of oxytetracycline (2 X 500 mg/day for 5 days) to 5 young male subjects. Furthermore urinary and fecal estrogens were determined in 1 male subject after administration of erythromycin for 6 days and in 2 normally menstruating women after tetracycline and trimethoprim administration, respectively. During treatment with antimicrobial drugs an increase in the excretion of fecal conjugated and, with the exception of the oxytetracycline experiments, also of unconjugated estrogens paralleled a decrease in urinary estrogen excretion, especially for E2 and E3. In both urine and feces the E1/E2 and E1 + E2/E3 ratios increased due to diminished reductive metabolism of estrogens in the gut. No significant effects on plasma unconjugated estrogen concentrations were observed. The results suggest that the intestinal bacterial flora plays a significant role in estrogen metabolism. However, further studies are necessary, because our results do not explain why administration of antibiotics may cause contraceptive failure.

Inhibition of 3-beta-hydroxy steroid dehydrogenase activity in first trimester human pregnancy with trilostane and WIN 32729

The effects of equivalent doses of two inhibitors of the 3-beta-hydroxy steroid dehydrogenase enzyme system--WIN 24540 (trilostane) and WIN 32729--on the secretion of progesterone in early human pregnancy are described. Patients and controls less than 12 weeks pregnant were given a single dose of either drug and the resultant hormonal changes monitored for 7 1/2 h. A consistent fall in plasma progesterone concentrations occurred at all doses and, at the highest dose, they fell to less than 50% of pre-treatment levels. However, whilst with trilostane the associated increase in plasma concentrations of pregnenolone was always accompanied by a rise in plasma DHA concentrations, with WIN 32729 there appeared to be no adrenal effect at the lower dosage levels. These data demonstrate inhibition of progesterone secretion in human pregnancy using non-hormonally active steroids. The pattern of steroid precursors indicates that while both drugs inhibit 3-beta-hydroxy steroid dehydrogenase activity, WIN 32729 is more selective and only interferes with adrenal steroid biosynthesis at high doses.

Metabolic effects of two triphasic formulations containing ethinyl estradiol and dl-norgestrel

The metabolic effects of two triphasic oral contraceptive (OC) preparations containing dl-norgestrel (dlN) and ethinyl estradiol (EE) were studied in young women. The marked difference in the two preparations was in the progestogen content, allowing the study of the metabolic effects of high and low progestogen in oral contraception. The results suggest that high progestogen increases serum sodium, potassium, blood urea nitrogen, creatinine, total protein, albumen, and lactic dehydrogenase. An increase in aspartate transaminase and a decrease in alkaline phosphatase were probably estrogen-related. High progestogen significantly reduced the fasting blood glucose levels (p less than .001). Both preparations significantly increased the levels of cholesterol and triglycerides in women who had not taken OCs for 3 or more months, and with the low progestogen preparation these increases are dissimilar to the effects reported in the triphasic preparations containing levonorgestrel.

Effects of oral contraceptive steroids on acetaminophen metabolism and elimination

Plasma acetaminophen elimination was examined in women taking low-dose estrogen oral contraceptive (OC) steroids and in age-matched control women. Fractional rates of elimination and fractional clearances were calculated for each of the metabolic pathways, including oxidation, sulfation, and glucuronidation. The cysteine adduct and mercapturic acid derivative of acetaminophen were used as an index of oxidative biotransformation, a potentially toxic route of metabolism for acetaminophen. Plasma acetaminophen clearance rose from 287 +/- 13 ml/min to 470 +/- 51 ml/min in women taking OC steroids, whereas elimination t1/2 decreased from 2.40 +/- 0.14 hr to 1.67 +/- 0.16 hr. The fractional clearance and rate of elimination of acetaminophen by glucuronidation increased in women taking OC steroids, whereas the clearance and elimination by sulfation did not differ significantly from values in control subjects. Fractional clearance of the cysteine adduct also increased significantly, but clearance of acetaminophen mercapturic acid did not change. These data suggest that the increased clearance of acetaminophen from plasma in women taking OC steroids results from increased glucuronidation of the drug, although the mechanism is not known.

Variability of pharmacokinetic parameters for contraceptive steroids

Studies of the pharmacokinetics of three contraceptive steroids, ethynyloestradiol, norethisterone and norethisterone oenanthate, in large groups of women are reviewed. Extremely wide variations were observed between women in the various calculated pharmacokinetic parameters. Studies carried out in small groups of subjects may give misleading results. It is difficult to ascribe any meaning and interpretation to most of the derived values but they do provide a means of comparing aspects of the metabolism of the various steroids. It is difficult to relate the pharmacokinetic values to the various biological actions of the steroids. However, the wide variations between subjects in the pharmacokinetic parameters must indicate equally wide variations in the biological activity of the steroids. Subjects in whom the bio-availability is low or where the rate of metabolism is rapid might be expected to respond differently, both in terms of efficacy and side-effects, from subjects with high values for bio-availability and a slow metabolism.

Prednisolone disposition and protein binding in oral contraceptive users

Combined estrogen-progestogen oral contraceptives (OC) have been shown to alter the metabolism of certain drugs, including corticosteroids, as well as affect circulating protein concentrations. To assess these effects with regard to prednisolone, the pharmacokinetics and protein binding of this steroid were evaluated in eight female OC users and compared with results from eight male and five female non-OC users. All volunteers received 40 mg prednisolone, iv, and steroid concentrations were measured by high pressure liquid chromatography. Plasma clearance of total prednisolone in females on OC was 96 +/- 9 (SD) ml/min X 1.73 m2, significantly (P less than 0.001) lower than those in both male and female controls (205 +/- 46 and 187 +/- 22 ml/min X 1.73 m2). The prednisolone half-life and mean residence time were longer, while the steady state volume of distribution was smaller for OC users. Unbound prednisolone was measured by equilibrium dialysis, and pharmacokinetic and protein binding parameters were calculated from free prednisolone concentrations. A significantly higher (2-fold) concentration of transcortin was found in OC users. Evaluation of free prednisolone parameters showed a significantly lower clearance and decreased volume of distribution, without alteration of the mean residence time for the OC users. Dual OC effects on binding and elimination of prednisolone occur with the net result of a 2-fold increase in the area under the free concentration-time curve, indicative of a marked reduction in the biotransformation rate of the steroid.

Differential effects of oral contraceptive steroids on the metabolism of benzodiazepines

The effects of oral contraceptive steroids (OCS) on the disposition and elimination of lorazepam, oxazepam, and chlordiazepoxide were examined. Lorazepam and oxazepam are metabolized via glucuronidation while chlordiazepoxide is metabolized by oxidation in the liver. The disposition and elimination of lorazepam, oxazepam, and chlordiazepoxide was studied in females not taking OCS and females taking OCS (norethindrone acetate, 1 mg; ethinyl estradiol, 50 micrograms) for 6 months or more. The t1/2 (beta) for lorazepam was significantly reduced in women taking OCS (6.0 +/- 3.1 vs. 14.0 +/- 6.2 hr) (p less than 0.005) as compared to controls, and the t1/2 (beta) for oxazepam was reduced in women taking OCS (7.71 +/- 3.23 vs. 12.09 +/- 5.08 hr) as compared to controls, but did not reach statistical significance. The plasma clearance of both lorazepam and oxazepam was significantly increased in women taking OCS [(288.9 +/- 165.9 vs. 77.5 +/- 3.29 ml per min) (p less than 0.01) and (251.2 +/- 106.9 vs. 97.86 +/- 69.4 ml per min) (p less than 0.01), respectively] as compared to controls. The volumes of distribution of lorazepam and oxazepam were significantly increased in women taking OCS (p less than 0.05) while plasma binding of these drugs was similar in both groups. In contrast, the t1/2 (beta) of chlordiazepoxide was significantly prolonged (20.58 +/- 8.08 vs. 11.63 +/- 5.91 hr) (p less than 0.05), and the plasma clearance was significantly reduced (13.41 +/- 4.69 vs. 33.22 +/- 12.37 ml per min) (p less than 0.05) in the OCS group as compared to controls. The volumes of distribution of chlordiazepoxide were similar in both groups, and the plasma binding of chlordiazepoxide tended to be lower in the OCS group but did not reach statistical significance. We conclude that OCS exert a differential effect on the elimination of benzodiazepines, whereby oxidation of chlordiazepoxide is impaired while the glucuronidation of lorazepam and oxazepam is enhanced by OCS.

Clinical chemistry in women treated with levonorgestrel implants (Norplant) or a TCu 200 IUD

Two groups of implant users and two groups of IUD users participated in the study at different times. In the first groups, fractionation of lipoproteins was performed on serum samples from 28 subjects who had used the implants for 37 months and from 26 subjects who had used the Copper TCu 200 for 30 months. Users of the implants had significantly lower levels of total cholesterol, triglycerides and LDL-cholesterol than users of the IUDs. HDL-cholesterol levels were not different between the groups. In the other groups of women, general chemistries and selected hormone assays were carried out on samples from 30 subjects who had used implants for 51 months and from 24 subjects who had used the TCu 200 IUDs for 43 months. The parameters studied were the SM-12 chemistry group profile, estradiol, cortisol, testosterone, triiodothyronine, thyroxine and thyroid stimulating hormone. In the implant group, mean serum glucose levels were statistically significantly elevated and inorganic phosphorus levels were significantly reduced as compared to the IUD group. In both cases all individual measurements were within the normal range for the population. Testosterone and triiodothyronine levels in the implant group were significantly lower than in the IUD group, but no individual values were outside the normal range for the population. Mean values for all other parameters were not significantly different between the groups.

A randomized prospective study of the metabolic effects of four low-estrogen oral contraceptives

Healthy, nonsmoking, normotensive, well-motivated young women were assigned at random to one of four different commercial, low-estrogen oral contraceptives. Measurements of biochemical parameters were made on two blood specimens collected from fasting subjects late in the pretreatment cycle, then again late in each treatment cycle for 12 months. All the women assigned to one product (0.5 mg norethindrone + 35 micrograms ethinyl estradiol) dropped out of the study before the end of the fifth cycle, but discontinuations with the other three products were few. Though the numbers of subjects were small, the groups were closely matched, and most of the metabolic differences were statistically significant. Products containing ethynodiol diacetate and norethindrone were associated with increases in serum total cholesterol and triglycerides but decreases in high-density-lipoprotein-cholesterol. In contrast, the levonorgestrel-containing preparation produced significantly less of an effect on these tests. A similar pattern was seen with a range of blood coagulation and fibrinolytic factors. Minimal alterations were seen with the levonorgestrel preparation, whereas those containing norethindrone or ethynodiol diacetate showed marked increases in factors I, VII, VIII and X and plasminogen, associated with a decrease in antithrombin III. Differences in the metabolic impact of the various commercially available low-estrogen preparations, combined with their effects on intermenstrual bleeding, allow a choice of the progestogen component most suitable for general use.

Plasma lipid changes and medroxyprogesterone acetate

Progestogens may have profound effects on lipid metabolism. Effects are generally dose-related and are more pronounced with 19-nor testosterone derivatives. Progestogens suppress circulating levels of high-density lipoprotein cholesterol (HDL-C) and increase circulating low-density lipoprotein cholesterol. Therefore, over a long period of time, the risk of atherosclerosis may increase. Although contraceptive use of depot medroxyprogesterone acetate (DMPA) reduced HDL-C levels by 15-20%, the levels generally remain within the normal range. Progestogens such as DMPA usually do not have any influence on fasting triglyceride levels. Some progestogens produce changes in the composition of phospholipids, but not DMPA. Progestogen effects on lipid metabolism are different from estrogen effects alone or estrogen-progestogen combinations. Increased risk of cardiovascular disease in longterm DMPA users is probably very small, but may become more significant when coupled with high risk factors. 10 years ago, most of the undesirable metabolic changes associated with the use of oral contraceptives were attributed to the estrogen component. 2 recent findings illustrate that certain progestogens can create metabolic havoc. 1) There is a strong association between depressed circulating levels of HDL-C and risk of serious cardiovascular disesase. 2) Certain progestogens are capable of substantially depressing the circulating levels of HDL-C, whereas estrogen actually elevates HDL-C. This does not prove that progestogens cause cardiovascular disease, but this possibility should be considered.

Drug control of steroid metabolism by the hepatic endoplasmic reticulum

In this review evidence is provided for the interaction between various drugs and steroid hormones in man and between drugs and progestogens in experimental animals. The mechanism by which these drug interactions occur are of fundamental biochemical and pharmacological interest. The importance of practical clinical considerations of drug-steroid interactions has also been discussed. In particular, considering the present tendency to lower the dose of progestogen and estrogen in most contraceptive preparations, any factor that reduces the bioavailability of the steroid hormones becomes very important. Other drugs and environmental chemicals may interact with these steroids and thereby diminish their efficacy. Clinical studies have reported that the most important interfering drugs are some anticonvulsants and antibiotics, and the antituberculosis compound rifampicin. Anticonvulsants and antituberculotics affect microsomal enzyme induction in the liver or interfere with enzyme systems in the gut wall. The action of antibiotics is connected with the pharmacokinetics of contraceptive steroids by an interaction with their enterohepatic circulation. Some environmental factors such as smoking, alcohol, and other dietary variations, and concurrent hepatic disease may modify the disposition of circulating endogenous steroids and exogenous contraceptive steroids. These effects may alter their response accordingly. In our studies drug treatments of rats reduced serum progesterone level irrespective of whether a potent inducer (phenobarbital, 4-methylcoumarin) or a hepatotoxin (carbon tetrachloride, coumarin, alpha-naphthylisothiocyanate) was administered. These treatments affected hepatic progesterone content. Phenobarbital and carbon tetrachloride reduced serum level, but the hepatic incorporation was enhanced by phenobarbital and reduced by carbon tetrachloride. The opposite actions were selective; phenobarbital raised the oxidative pathway of progesterone metabolism but did not modify the reductive pathway. This drug also enhanced progesterone 16 alpha-, 6 beta-, and 20 alpha-hydroxylase, but did not alter delta 4 - 5 alpha-reductase. In contrast, carbon tetrachloride inhibited hydroxylase and enhanced reductase activities. The effects of these test compounds on progesterone-metabolizing enzymes in isolated microsomes in vitro were similar to the in vivo results. It is concluded that the action of various drugs on serum and liver progesterone levels and metabolism is probably related to changes manifest in the function of the hepatic endoplasmic reticulum.

Metabolic effects of the triphasic oral contraceptive Trigynon

Effects of Trigynon, a triphase low-dose oral contraceptive, containing ethinylestradiol and l-norgestrel in various proportions, on testosterone binding globulin, transcortin, thyroxine, free testosterone, free cortisol and free thyroxine as well as on plasma lipids and glucose tolerance were studied in 12 normal women treated for 3-6 months. Trigynon appears to have dominant estrogenic effects as evidenced from the increase in transport proteins and the decrease in free testosterone concentration. Plasma lipids were not significantly influenced; glucose tolerance was slightly, but not significantly decreased.

The influence of oral contraceptives on the metabolism of methaqualone in man

1 Oral contraceptives were shown to suppress the mid-cycle increase in methaqualone metabolism observed in premenopausal women not receiving oral contraceptive therapy. No women were identified in whom this suppression was not observed. 2 Combined oestrogen-progestogen contraceptives produced the effect in all nine women studied. The effect was also observed in one woman who was receiving progestogen-only contraceptives. 3 The effect of the combined contraceptives was observed within one month of the commencement of the contraceptive therapy. 4 The results emphasise the need to monitor the effect of the menstrual cycle in women not receiving oral contraceptive therapy when the effects of such therapy is studied. 5 These effects are more likely to be the consequence of an inhibition of hormonal control of hepatic metabolic activity by the synthetic steroids than they are to simple inhibition of hepatic metabolism.

The gut wall metabolism of ethinyloestradiol and its contribution to the pre-systemic metabolism of ethinyloestradiol in humans

1 Five patients have been studied to determine the contribution of the gut wall to the pre-systemic metabolism of ethinyloestradiol. All patients had a catheter inserted into their hepatic portal vein as part of their surgical management. 2 After an oral dose of 50 micrograms (65 microCi) ethinyloestradiol, blood samples were taken from the hepatic portal vein and from a peripheral vein at intervals for 1 h. 3 In each patient the concentration of conjugated ethinyloestradiol in the portal vein was considerably higher than in the peripheral vein. 4 Although a number of assumptions have been made, calculations showed that the gut wall appeared to be twice as effective as the liver in conjugating ethinyloestradiol on the first pass. 5 In two patients there was no evidence of major uptake or metabolism of ethinyloestradiol in the lung.

Long acting injectable hormonal contraceptives

Injectable hormonal preparations can be highly effective and satisfactory contraceptives. The two main preparations available today are depot medroxy progesterone acetate (DMPA) and norethisterone oenanthate (NET-OEN), but several other approaches are currently under clinical trial. Injectable contraceptives have some unique advantages which give them justifiably wide appeal amongst many groups of women. However, they do have a number of disadvantages including invariable menstrual disturbance and a delay in the return of fertility. One formulation of DMPA, Depo-Provera, is probably the most extensively investigated single hormonal contraceptive ever made. These studies indicate that it is remarkably safe and does not face any more unresolved issues than the combined pill, intrauterine device or tubal sterilization. However, for a number of disparate emotional and political reasons it has attracted the attention of several consumer and feminist groups, who have waged a prolonged and quite unjustified campaign against it. It is to be hoped that future debate will be conducted on a more informed, rational and less emotional basis. Injectable contraceptives should have an important place in the family planning armamentarium of all countries, and current developments should lead to a decrease in concerns about presently available agents. This should further increase the widespread acceptability of this approach to contraception.

A new progestagen for oral contraception

Desogestrel (13-ethyl-11-methylene-18, 19-dinor-17alpha-pregn-4-en-20-yn-17-ol) is a new potent progestagen suitable for incorporation into combined oral contraceptives (OC)s. 2 products have thus far been developed, 1 containing 150 mcg desogestrel plus 30 mcg ethinyl estradiol (EE)/tablet (Marvelon) and the other a normophasic product containing 50 mcg EE (7 tablets) followed by 125 mcg desogestrel plus 50 mcg EE (15 tablets). No tablet failures were reported in large-scale multicenter trials. Clinical studies, confirmed by receptor studies, showed that desogestrel lacks androgenicity in the dosages used. Also, studies on lipid metabolism revealed that desogestrel does not abolish EE-induced rises in HDL cholesterol. Since low levels of HDL cholesterol have been associated with an increased risk of ischemic heart disease, this can be regarded as a favorable aspect of desogestrel. In view of increasing demands for safer OCs, it can be concluded that preference should be given to OCs containing this progestogen.

Neurotransmitter modulation of steroid action in target cells that mediate reproduction and reproductive behavior

Two major functional interactions between steroid hormones and neurotransmitters are generally recognized. First, steroids affect neurotransmission, and second, through effects on hypothalamic peptides that regulate anterior pituitary function neurotransmitters affect steroid secretion. In recent years, evidence has accumulated which indicates that neurotransmitters can also affect steroid action within postsynaptic steroid target cells. We review evidence for this relationship in pineal, uterus and hypothalamus and propose that the modulation of target cell responsiveness to steroids is an important mechanism by which neurotransmitters affect steroid-dependent processes. The operation of such a mechanism provides a means for environmental, behavioral and emotional events to rapidly and selectively alter steroid effects on behavior and physiology.

[Hypophyseal reaction state during oral contraceptiva (author's transl)]

In 5 normocyclic women, firstly taking a conventional oral contraceptive, Neogynon (50 mcg EE + 250 mcg levo-norgestrel) for 6 months, the levels of LH, 17 beta-E2 and progesterone did not rise after changeover to a dose-reduced pill, Microgynon 30 (30 mcg EE + 150 mcg levo-norgestrel). This fact indicates maintained central suppression. Examination of the hypothalamic-hypophyseal axis by the Gn-RH test (50 mcg) with Microgynon 30 showed negative results during the first treatment cycle in 13 out of 18 women. In the 6th treatment cycle only 7 Gn-RH non-reactive women were observed and after stimulation with 100 mcg Gn-RH only 5 women remained with negative Gn-RH tests. Of the 20 women who took conventional oral contraceptives over a period of 6 months to 6 years (7 took Eugynon: 50 mcg EE + 500 mcg D,L-norgestrel, 5 Lyndiol: 75 mcg mestranol + 2.5 mg lynoestrenol, 8 Neogynon, only one from the Neogynon group showed a positive result. On the other hand there was a positive reaction in 4 out of 7 women using the two step dose-reduced preparation Sequilar (11 tablets of 50 mcg EE + 50 mct levo-norgestrel and 10 tablets of 50 mcg EE + 125 mcg levo-norgestrel).