Pharmacokinetics of the fetal estrogen estetrol in a multiple-rising-dose study in postmenopausal women.

OBJECTIVES: Estetrol (E4) is a natural fetal estrogen. In this open-label, multiple-rising-dose study, the pharmacokinetic effects of E4 in postmenopausal women were investigated as a secondary objective. METHODS: In total, 49 postmenopausal women were randomized to receive either 2 mg E4 or 2 mg estradiol valerate (E2V) for 28 days, or were (non-randomized) assigned to 10, 20, or 40 mg E4. The main outcome measures were: E4 plasma concentrations at trough, and on days 1 and 28; and E4 pharmacokinetic parameters AUC, Cmax and tmax on days 1 and 28. RESULTS: After oral administration, E4 showed a very fast absorption, followed by a multiphasic elimination with an initial rapid decline, gradually continuing with a slower elimination, suggesting a long terminal half-life. Steady state was reached within 2 weeks of dosing and pharmacokinetic results were generally proportional to the dose. Estetrol concentrations on day 28 were slightly higher compared to day 1, indicating some accumulation. CONCLUSION: The pharmacokinetic profile of estetrol is characterized by a very fast absorption phase, followed by an initial rapid decline, and a slow terminal elimination phase. Based on its kinetic properties, estetrol seems suitable for use as a once-daily oral drug.

Automated direct high-performance liquid chromatographic assay for estetrol, estriol, cortisone and cortisol in serum and amniotic fluid.

An automated direct assay for the simultaneous determination of unconjugated estetrol, estriol, cortisone and cortisol in serum and amniotic fluid, using high-performance liquid chromatography with electrochemical detection and ultraviolet detection, has been developed. The analysis time is ca. 1 h. This system offers good reproducibility with low coefficients of variation (estetrol, 2.3%; estriol, 2.3%; cortisone, 2.6%; cortisol, 1.9%). Detection limits are low enough for routine determinations (estetrol and estriol, 150 pg; cortisone and cortisol, 5 ng). Comparison of the values measured by the present method and by radioimmunoassay revealed significant correlations for estetrol (r = 0.787, p less than 0.01), estriol (r = 0.957, p less than 0.01), cortisone (r = 0.956, p less than 0.01) and cortisol (r = 0.865, p less than 0.01). This system proved to be valuable in monitoring feto-placental function.

[Study on the clinical evaluation of DHAS loading as a fetoplacental function test--effect of DHAS on estrogen metabolism at a fetoplacental unit].

To evaluate estrogen metabolism in the fetoplacental unit after dehydroepiandrosterone-sulfate (DHAS) injection to the mother, unconjugated estrone, estradiol, estriol and estetrol in maternal vein (MV), umbilical vein (UV), umbilical artery (UA) and amniotic fluid (AF) were measured after DHAS injection. Eighteen normal obstetric patients (37-39W) on whom was performed elective repeat cesarean section were injected with 100 mg of DHAS 30-60 minutes (7 cases), 120 minutes (6 cases), 180-240 minutes (5 cases) before delivery. The injection of DHAS to the mother resulted in a rapid marked rise in estradiol levels in MV (400% of control) and estrone levels in UV (1480% of control). The rise in estrone levels in MV was slower than that of estradiol. The increase in estradiol in UV and UA was significant, but the values were lower than that in MV. No significant changes in estriol levels in each compartment were demonstrated. However, a significant increase in estetrol was observed in each compartment by 4 hours. A significant correlation was found between individual MV and UV plasma estetrol concentrations. These results indicate that placenta secretes estrone and estradiol asymmetrically to maternal and fetal circulation after DHAS injection. Determination of the maternal estradiol and estetrol rise after DHAS injection may reflect placental and fetoplacental function, but estriol may not.

Daily variation of serum unconjugated estriol and estetrol in normal pregnancy.

Serum unconjugated estriol and estetrol were assayed daily in seven nondiabetic, uncomplicated third-trimester pregnancies to define the daily variation of these compounds. When compared to the mean of the three preceding days' values, or to the highest mean of three consecutive daily values previously obtained in a pregnancy, daily estriol and estetrol values fell greater than or equal to 40% on 1.2 and 0% of occasions, respectively. Isolated estriol values represented falls of greater than or equal to 40% from previously obtained single estriol values on 2% of occasions, and no isolated estetrol values fell greater than or equal to 40% from any other isolated values obtained in a given pregnancy. These results define the stability of daily serum estriol and estetrol in late-gestation normal pregnancy, although they emphasize the large variability encountered when comparing isolated estriol values.

Dehydroepiandrosterone sulphate loading test and determination of plasma oestetrol concentration in late pregnancy.

Intravenous application of dehydroepiandrosterone sulphate (DHEA-S) was performed in 6 women with normal progress of pregnancy, 3 pregnant women with multiple pregnancy and 4 pregnants with intrauterine death of the foetus (32nd to 38th week). The oestetrol concentrations in blood serum were estimated during 5 h after the injection. In most cases an increase could be observed, but this was inhomogenous. The oestetrol concentration even rises in cases of intrauterine death of the foetus. In 7 cases of uncomplicated pregnancies the DHEA-S loading test was done within 2 to 6 h before delivery. The oestetrol concentration in the cord serum of the newborns was not higher than in controls without DHEA-S application, whereas oestradiol in maternal serum showed the expected rise. We conclude that the determination of oestetrol after DHEA-S loading can not be used for the judgement of the foetal situation.

Rapid and simultaneous measurement of estrone, estradiol, estriol and estetrol in serum by high performance liquid chromatography with electrochemical detection.

A high performance liquid chromatographic (HPLC) method with electrochemical detection (ECD) was developed for the simultaneous measurement of estrone, estradiol, estriol and estetrol in serum. These hormones were extracted with diethylether, chromatographed on an silica-octadecyl silane (ODS) column with an eluent of phosphate buffer solution-acetonitrile-methanol (volume ratio 152:85:40), and detected by ECD at +1.0V vs. Ag/AgCl. In comparisons between the values measured by this method and radioimmunoassay, significant correlations were noted for estrone (r = 0.759, p less than 0.01), estradiol (r = 0.816, p less than 0.001) and estriol (r = 0.830, p less than 0.001). In clinical applications of this method, differences between cases of the normal and the anencephalic pregnancy in the thirty-eighth week of gestation were distinct not only in the individual estrogen, but also in the profile analysis of estrogens. With this method, all 4 serum estrogens above approximately 500 pg/ml could be measured within 2 h, and the method seemed to be clinically applicable.

Diagnosis of growth retardation by biochemical methods.

The substances in the blood or urine of a pregnant woman which may give an indication of the state of fetal growth are examined. The drawback of measuring such substances is that the values are variable, making it difficult to distinguish between normal and abnormal. Variability arises from technical factors in measurements, from short-term changes of no significance and from the large spread of normal values from one individual to the next. Biochemical parameters of fetal growth can be applied in one of two ways: as screening tests or as control measures by serial assays to guide management. The criteria by which any test should be evaluated--sensitivity, specificity and relative risk--are examined. Particular substances whose measurement may be helpful are considered in terms of the steroids or proteins produced by the fetoplacental unit. The oestrogens, notably oestriol, hold pride of place among the steroids. Dynamic tests of steroid synthesis are also considered. The chief placental proteins of interest are chorionic gonadotrophin, placental lactogen and Schwangerschaftsprotein 1. It is concluded that the method to be recommended is to screen a whole obstetric population with assays of placental lactogen and to follow those with values below the normal limit with serial oestriol assays.

Individualized cosinor assessment of circadian hormonal variation in third trimester human pregnancy.

Two clinically healthy pregnant women were studied in a single 24-h span during the third trimester. Blood drawn every 20 min was assayed for cortisol (F), dehydroepiandrosterone sulfate (DHEA-S), estriol (E3), and prolactin (PRL). Blood drawn hourly was assayed for progesterone (P), human placental lactogen (HPL) and 15alpha-hydroxyestriol (E4). Breast temperature (BT) was continuously monitored. Single cosinor analysis demonstrated statistically significant circadian rhythms for plasma concentrations of F, DHEA-S, and BT for both subjects, and of E3 for one subject. Statistically significant circadian rhythms in plasma concentrations of P, HPL, E4 or PRL could not be demonstrated in our third trimester subjects. However, analysis of data from subjects sampled at earlier gestational ages revealed highly significant PRL circadian rhythms. These results suggest that plasma concentrations of PRL show a progressive decrease in circadian amplitude despite a progressive increase in mesor with advancing gestational age. Frequent sampling and cosinor data analysis permit identification of circadian rhythms in BT. The use of BT as a potential marker for rhythms in plasma concentration of certain hormones awaits further scrutiny. The demonstration of several circadian endocrine rhythms in individual subjects in the third trimester of human pregnancy facilitates the usefulness of such marker rhythms.

[Determination of serum unconjugated estetrol by selected ion monitoring with application of deuterated estetrol as an internal standard].

A rapid and highly specific method for determination of serum estetrol during pregnancy and at delivery is developed using a gas chromatography-mass spectrometry with application of newly synthesized deuterated estetrol as an internal standard. Evaluation of the method assessed by recovery experiments was 102.4 and 103.0 percent when 2 and 4ng of estetrol was added to 0.5ml of male serum. The coefficient of variation were 2.54 and 2.84 percent, respectively. The results obtained by the present method are correlated well with those obtained by conventional RIA. Serum unconjugated estetrol levels during pregnancy increased with progressing gestation. The levels from the 36th to the 40th week were 749.8 +/- 281.5pg/ml (mean +/- S.D.) The levels in umbilical cord blood at delivery were also measured: Umbilical vein were 8,064.0 +/- 6,595.4pg/ml which were statistically higher than in umbilical artery (3,515.9 +/- 1,553.8pg/ml) and in maternal peripheral vein (1,209.0 +/- 530.3pg/ml).

[Effect of bromocriptine on the endocrine profile during pregnancy].

In this paper, we revealed the changes in maternal plasma concentration of PRL, HCG, HPL, progesterone (P), estradiol-17 beta (E2), estriol (E3), estetrol (E4) and dehydroepiandrosterone-sulfate (DHEA-S) after the administration of bromocriptine during pregnancy. Blood samples were collected from 23 women with gestation ranging from 7 to 28 weeks. Sixteen patients had therapeutic abortion and other 7 patients had inevitable abortion. PRL, HCG, HPL, P, E2, E3, E4 and DHEA-S were measured by radioimmunoassay. The PRL decreased significantly at 120 and 180 minutes after the administration of bromocriptine in any case. In 4 cases out of 10 cases in early normal pregnancy, plasma E2 level decreased to 50% lower than the basal level, but no significant change of E2 occurred after bromocriptine in early and mid pregnancy. Bromocriptine made no change in HCG, HPL, P, E3, E4 and DHEA-S for any group. Our data suggested that bromocriptine had effect on only plasma PRL level, and this drug or the change of PRL level had no effect on P, estrogen, DHEA-S, HPL and HCG concentration during pregnancy.

Estetrol and utero-placental flow after progesterone load.

On the basis of recent demonstration in animals of the effect of some hormones on uteroplacental flow, the Authors examined the response of plasmatic Estetrol (15 alpha-hydroxy-estriol) after the administration of progesterone to pregnant women with low Estrogen values. The increase of this compound was related to an improvement of placental function, probably dependent on an increase of available O2, and therefore on uterine blood flow. This can justify a progesterone treatment in such pregnancies.

Unconjugated estetrol in normal pregnancy.

The Authors studied the levels of Estetrol (15 alpha-hydroxyestriol) in the amniotic fluid, in maternal and foetal plasma, by the RIA method, in near-term pregnancies. Higher concentrations of this steroid were found in the foetal plasma and in amniotic fluid than in the maternal plasma. These data, even though of little clinical importance, confirm the foetal origin of this compound and suggest further studies, especially in the amniotic compartment.

What are the most suitable fetoplacental tests in the monitoring of the third trimester of pregnancy?

The case-series of the Institute of Obstetrics and Gynaecology were examined to evaluate the suitability of urinary estriol, total plasma estriol, unconjugated plasma estriol, unconjugated plasma estetrol, plasma placental lactogen, plasma S.P.-1 glycoprotein, plasma alphafetoprotein and biparietal diameter in correctly forecasting the perinatal risk, when performed after the 25th week of pregnancy. In high-risk pregnancies, according to our results, S.P.-1 glycoprotein and urinary estriol are the most sensitive tests, while S.P.-1 glycoprotein, placental lactogen and biparietal diameter are found to have the highest predictive value. The repetition of the considered tests increases their sensitivity, but not their predictive value. In pregnancy mass screening the most suitable tests, on the basis of the "relative risk" are S.P.-1 glycoprotein (or even placental lactogen), estriol and biparietal diameter. For the last one a single measurement seems to be enough during the third trimester.