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PubMed1993

Absence of an effect of high vitamin C dosage on the systemic availability of ethinyl estradiol in women using a combination oral contraceptive.

Previous studies in small numbers of women have suggested that the administration of gram quantities of ascorbic acid interferes with the conversion of ethinyl estradiol (EE2) to its sulfates, leading to higher blood levels of EE2. The possibility of such potentiation has been investigated in 37 women using a combination monophasic oral contraceptive (30 micrograms EE2 and 150 micrograms levonorgestrel) for two consecutive cycles. Concomitant daily administration of 1 g ascorbic acid taken 1/2 hour before OC intake, was randomly assigned to the first or second cycle of OC use. On the first and 15th day of OC intake, blood samples were drawn 11 times over a 12-hour interval and Cmax and AUC(0-12 h) calculated. On pill days 10 and 21, only 6-hour post-intake samples were obtained. Samples were analyzed for levels of ascorbic acid, free and sulfated ethinyl estradiol (and a number of other parameters). Cmax and AUC values for EE2 and EE2-sulfate in cycles with and without ascorbic acid were evaluated statistically by the Grizzle model for days 1 and 15 and the ratios of day 15/day 1 for each of the substances. No effect of ascorbic acid was observed (alpha = 0.05, 1-beta = 0.9). Only on day 15 was there a significantly lower AUC for EE2-sulfate in the presence of ascorbic acid intake. Thus, the competition between ascorbic acid and EE2 for sulfation does not lead to an increased systemic availability of EE2 and is, therefore, unlikely to be of any clinical importance. Ascorbic acid can, therefore, be removed from the list of drugs interfering with the pharmacokinetics of ethinyl estradiol.

Adolescent↗
PubMed1984

Absence of antibodies to ethinyl estradiol in users of oral contraceptive steroids.

Sera from current and past oral contraceptive users, never-users, and never-users with venous thrombosis were examined for immunoglobulin G (IgG) which was precipitable at 25% or 33% saturation with ammonium sulfate or which showed specific binding of ethinyl estradiol. No increase in "specific" IgG and no evidence of ethinyl estradiol binding was observed in oral contraceptive users. This provides no support for the claim that a significant percentage of oral contraceptive users develop a special IgG, precipitable at 25% ammonium sulfate saturation and showing high binding affinity to ethinyl estradiol, which may be causally linked to the development of thrombotic phenomena in oral contraceptive users.

Antibodies↗
PubMed1998

Effect of two oral contraceptives containing ethinyl estradiol and gestodene or norgestimate on different lipid and lipoprotein parameters.

The effect of a triphasic oral contraceptive containing ethinyl estradiol and gestodene (EE/GSD) on various lipid and lipoprotein parameters was compared with that of a monophasic formulation containing 35 micrograms ethinyl estradiol and 250 micrograms norgestimate (EE/NGM). Blood samples were collected from 46 women on days 2, 11, and 21 of the preceding control cycle and of the third, sixth, and twelfth treatment cycles. There was no significant difference between formulations with regard to the influence on any measured parameter. As compared with controls, a significant increase was observed in the plasma levels of total triglycerides (24-78%), total phospholipids (7-20%), very low density lipoprotein (VLDL) triglycerides (61-76%), VLDL-phospholipids (14-60%), low density lipoprotein (LDL) triglycerides (8-35%), LDL-phospholipids (28-30%), high density lipoprotein (HDL) cholesterol (8-16%), HDL 3-cholesterol (11-20%), HDL-triglycerides (17-66%), HDL-phospholipids, HDL 3-phospholipids (7-11%), apolipoprotein (apo) A-I (5-20%) and apo A-II (10-40%) during treatment with both formulations. In contrast, the LDL-cholesterol levels were significantly decreased. These changes in lipid metabolism appear to reflect a predominance of the effect of the estrogen component. The results indicate that both low dose oral contraceptives containing different progestins and different amounts of EE do not exert a deleterious effect on lipoprotein metabolism, as high HDL-cholesterol and low LDL-cholesterol levels are known as low risk factors of cardiovascular disease. In contrast to endogenous hypertriglyceridemia, an EE-induced rise in triglyceride levels does not appear to increase cardiovascular risk if LDL is not increased.

Adolescent↗
PubMed1978

Disposition of norgestimate in the presence and absence of ethinyl estradiol after oral administration to humans.

The disposition of radioactivity following oral administration of 14C-norgestimate was compared to that following administration of the drug in combination with 3H-ethinyl estradiol in humans. Seven normal, healthy female subjects were each administered one capsule orally containing 14C-norgestimate either alone (74.4 muCi, 0.50 mg) or in combination (73.5 muCi, 0.49 mg) with 3H-ethinyl estradiol (103 muCi, 0.14 mg) in polyethylene glycol 400. Peak levels of radioactivity due to carbon-14 and tritium in plasma occurred within 2 hr after drug administration, followed by distribution and elimination phases. The mean apparent elimination half-life and mean cumulative elimination of radioactivity in the urine and feces following 14C-norgestimate administration were not significantly different than those following administration of the combination dose. Approximately 50% of the administered radioactivity due to carbon-14 was excreted in the urine following administration of 14C-norgestimate both in the presence and absence of coadministered 3H-ethinyl estradiol.

Administration, Oral↗
PubMed1988

Coregulation of C3-hydroxyl versus C17-hydroxyl glucuronidation of beta-estradiol in pregnancy and after treatment with phenobarbital or ethinyl-estradiol.

The glucuronidation of [3H]estradiol-17 beta at the C3 vs. the C17 hydroxyl groups was determined in female Sprague-Dawley rat liver microsomes. A high-performance liquid chromatography method was developed to resolve the glucuronide conjugates which were then quantitated by liquid scintillation counting. The rates of formation of 17 beta-estradiol 3-(beta-D-glucuronide) (E(2)3G) and 17 beta-estradiol 17-(beta-D-glucuronide) (E(2)17G) were 0.49 +/- 0.03 and 0.40 +/- 0.02 nmol/min/mg of protein, respectively. The apparent Km and Vmax of estradiol glucuronidation were determined in control, pregnant (day 19 of gestation), phenobarbital-treated (80 mg/kg/day i.p. for 5 days) and ethinylestradiol-treated (5 mg/kg/day i.p. for 5 days) female rats. The least-squares estimates of Km and Vmax values as well as the confidence contours of the joint sums of squares for the parameter spaces were calculated. The Vmax (nanomoles per minute per milligram of protein) for E(2)3G was significantly decreased from 0.94 to 0.57 in pregnancy and to 0.47 as a result of ethinylestradiol treatment. The Vmax values for E(2)17G were significantly different in control (0.43), pregnant (0.31) and ethinylestradiol-treated (0.27) rats. Phenobarbital treatment slightly increased the Vmax to 0.51 for E(2)17G whereas the Vmax for E(2)3G was unchanged (0.90) compared to controls. The Km (micromolar) for E(2)3G was 144 in the controls, 112 in pregnancy and 86 and 92 as a result of treatment with ethinylestradiol and phenobarbital, respectively. The Km for E(2)17G was 60 in the controls, 40 in pregnancy, 43 and 68 as a result of ethinylestradiol and phenobarbital treatment, respectively. None of the changes in Km were statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Algorithms↗
PubMed1997

Modulation of ovarian function by an oral contraceptive containing 30 micrograms ethinyl estradiol in combination with 2.00 mg dienogest.

Twenty-two healthy female volunteers with normal ovulatory cycles, aged between 20 and 34 years (27.3 +/- 4.1), were included in a single-center, noncomparative study to investigate the modulation of ovarian function by an oral contraceptive containing 30 micrograms ethinyl estradiol in combination with 2.00 mg dienogest. At baseline, during three treatment cycles and post-treatment, serum levels of luteinizing hormone, follicle-stimulating hormone, 17 beta-estradiol, and progesterone were assayed and ultrasonography was used to measure follicular size and the thickness of the endometrium. The primary efficacy variable was inhibition of ovulation as measured by ovarian activity grading. All volunteers ovulated during the pretreatment cycle. During treatment, none of the subjects had ovulatory cycles, although there was still some ovarian activity in several subjects. During the first treatment cycle, only 4% (1 subject) of cycles showed active follicle-like structures. The frequency of follicle-like structures increased to 33% and 35% during treatment cycles 2 and 3. The frequency of presumptive luteinized unruptured follicle-like structures was 5% (1 subject) and 15% (3 subjects) in treatment cycles 2 and 3. The serum hormone concentrations were effectively suppressed in comparison to baseline. The ovarian activity returned to baseline during the post-treatment period. One subject was excluded from further study because of a medical problem believed unrelated to use of the oral contraceptive. No serious adverse events were recorded during the course of the study. The results of the present investigation indicate that the modulatory effects on ovarian function of the monophasic oral-contraceptive containing 30 micrograms ethinyl estradiol combined with 2.00 mg dienogest lead to adequate suppression of ovarian activity and effective inhibition of ovulation.

Adult↗
PubMed1994

Modification of the U.S.P. dissolution method for the analysis of norethindrone and ethinyl estradiol tablets.

A modification of the U.S.P. dissolution method for the quantitation of norethindrone and ethinyl estradiol tablets is proposed. This modification consists of the use of distilled water as the dissolution medium instead of 0.1 N hydrochloric acid (HCl) and/or neutralization of 0.1 N HCl with sodium carbonate prior to analysis. Statistical analysis of the results indicate that there are no significant differences between the dissolution in 0.1 N HCl and the dissolution in distilled water (p < 0.05) for norethindrone and ethinyl estradiol.

Chromatography, High Pressure Liquid↗
PubMed2001

Effect of two oral contraceptives with different ethinyl estradiol and levonorgestrel concentrations on the urinary excretion of biochemical vasoactive markers.

In the present study the effect on the urinary excretion of vasoactive markers of two oral contraceptives (OCs), i.e., Leios, containing 0.02 mg ethinyl estradiol and 0.1 mg levonorgestrel, and Stediril 30, containing 0.03 mg ethinyl estradiol and 0.15 mg levonorgestrel, was investigated. cGMP, prostacyclin and its antagonist thromboxane, serotonin, and urodilatin, a natriuretic and diuretic peptide formed in the kidney, were measured as markers. In a comparative, double-blind, randomized, parallel group study, 34 women received Leios and 33 women Stediril 30. Nocturnal urine was collected before treatment and during cyclic treatment after 3 and 12 cycles. Both contraceptives significantly enhanced cGMP excretion after 12 cycles. The prostacyclin metabolite remained unchanged for both formulations, but the excretion of the thromboxane metabolite was significantly decreased after 12 cycles. Thus, the ratio of prostacyclin to thromboxane, crucial for the resulting effect on vascular tone, increased significantly. For the serotonin metabolite, no changes were observed for both contraceptives. The excretion of urodilatin significantly increased for both preparations after 12 cycles compared to the pretreatment values. These results indicate that the low-dose OCs Leios and Stediril 30 may stimulate the production of some vasoactive markers, at least after 12 cycles of treatment. The positive influence of these contraceptives on the various markers investigated may improve vascular tone, impede development of atherosclerosis and arterial thrombosis, and improve water and electrolyte homeostasis. These effects most likely can be attributed to the estrogenic component. Levonorgestrel may elicit no impact on these estrogen-induced changes that, however, seem only to be manifested after a longer treatment period.

Adult↗
PubMed2005

Simultaneous determination of norethindrone and ethinyl estradiol in human plasma by high performance liquid chromatography with tandem mass spectrometry--experiences on developing a highly selective method using derivatization reagent for enhancing sensitivity.

In the present work, for the first time, a liquid chromatographic method with tandem mass spectrometric detection (LC-MS/MS) for the simultaneous analysis of norethindrone, and ethinyl estradiol, was developed and validated over the concentration range of 50-10000pg/ml and 2.5-500pg/ml, respectively, using 0.5 ml of plasma sample. Norethindrone, ethinyl estradiol, and their internal standards norethindrone-(13)C2, and ethinyl estradiol-d4, were extracted from human plasma matrix with n-butyl chloride. After evaporation of the organic solvent, the extract was derivatized with dansyl chloride and the mixture was injected onto the LC-MS/MS system. The gradient chromatographic elution was achieved on a Genesis RP-18 (50 mm x 4.6 mm, 3 microm) column with mobile phase consisted of acetonitrile, water and formic acid. The flow rate was 1.0 ml/min and the total run time was 5.0 min. Important parameters such as sensitivity, linearity, matrix effect, reproducibility, stability, carry-over and recovery were investigated during the validation. The inter-day precision and accuracy of the quality control samples at low, medium and high concentration levels were <6.8% relative standard deviation (RSD) and 4.4% relative error (RE) for norethindrone, and 4.2% RSD and 5.9% RE for ethinyl estradiol, respectively. Chromatographic conditions were optimized to separate analytes of interest from the potential interference peaks, arising from the derivatization. This method could be used for pharmacokinetic and drug-drug interaction studies in human subjects.

Chromatography, High Pressure Liquid↗
PubMed1997

Effect of topiramate on the pharmacokinetics of an oral contraceptive containing norethindrone and ethinyl estradiol in patients with epilepsy.

PURPOSE: Because enzyme-inducing antiepileptic drugs (AEDs) can affect pharmacokinetics of oral contraceptives and thereby cause contraceptive failure, the potential effect of topiramate, a new AED, on the pharmacokinetics of the combination oral contraceptive norethindrone/ethinyl estradiol was evaluated. METHODS: Twelve women receiving stable valproic acid (VPA) monotherapy for epilepsy received a combination norethindrone 1.0 mg/ethinyl estradiol 35-microg tablet daily for 21 days followed by seven daily doses of inert tablets for four 28-day cycles. After a baseline cycle (cycle 1), topiramate 100, 200, and 400 mg every 12 h was administered in cycles 2 through 4, respectively. Serial blood samples were obtained on day 20 of each cycle and were analyzed for norethindrone, ethinyl estradiol, and progesterone by using validated radioimmunoassay methods. RESULTS: Compared with cycle 1, none of the norethindrone pharmacokinetic parameters changed significantly in the presence of topiramate, 100-400 mg every 12 h. Individual patient serum progesterone concentrations measured during each cycle were at or close to the limit of quantification with no apparent differences among cycles. However, mean area under the concentration-versus-time curve over the 24-h period (AUC(0-24)) values for ethinyl estradiol were 18-30% lower in cycles 2 through 4 compared with cycle 1 (p < or = 0.05 for all pairs), whereas mean oral serum clearance (CL/F) values were 14.7-33.0% higher (p < or = 0.05 for cycles 2 and 4 vs. cycle 1). Mean time of peak concentration (T(max)) values determined during topiramate therapy were not significantly different from those at baseline. CONCLUSIONS: When prescribing an oral contraceptive for patients receiving topiramate, clinicians should consider initial therapy with an agent containing > or = 35 microg of ethinyl estradiol.

Adult↗
PubMed2005

Interaction of St. John's Wort with oral contraceptives: effects on the pharmacokinetics of norethindrone and ethinyl estradiol, ovarian activity and breakthrough bleeding.

OBJECTIVES: This study evaluated the effect of the herbal remedy St. John's Wort on oral contraceptive (OC) therapy with respect to the pharmacokinetics of norethindrone and ethinyl estradiol, ovarian activity and breakthrough bleeding. METHODS: Sixteen healthy women were treated with a low-dose OC (Loestrin 1/20) and a placebo for two consecutive 28-day cycles in a single-blind sequential trial. Treatment with St John's Wort 300 mg three times daily was then added for two additional 28-day cycles. Outcomes compared between control and treatment cycles included the pharmacokinetics of norethindrone and ethinyl estradiol, daily bleeding diaries, follicle growth, changes in cervical mucus and progesterone levels drawn at 7- to 10-day intervals. RESULTS: Treatment with St. John's Wort was associated with a significant 13-15% reduction in the dose exposure from the contraceptive. Breakthrough bleeding increased in the treatment cycles, as did evidence of follicle growth and probable ovulation. CONCLUSION: St. John's Wort is associated with increased metabolism of norethindrone and ethinyl estradiol, breakthrough bleeding, follicle growth and ovulation. Women using OCs should be cautioned that St. John's Wort might interfere with contraceptive effectiveness.

Adult↗
PubMed1975

Mutual modification of glucose-stimulated serum insulin responses in female rhesus monkeys by ethinyl estradiol and nortestosterone derivatives.

Changes in iv glucose tolerance (IVGTT) and serum insulin responses to glucose infusion have been measured in intact female rhesus monkeys treated per os with norethindrone or medroxyprogesterone acetate (500 mug/day) both alone and in combination with mestranol or ethinyl estradiol (10 mug/day) orally for 3 weeks. When administered as the sole contraceptive steroid, neither norethindrone, medroxyprogesterone acetate, mestranol, or ethinyl estradiol produced consistent changes in fasting serum insulin or glucose concentration, mean intravenous serum glucose disappearance rates (K) or mean integrated serum insulin response to glucose (sigmal40). By contrast, concurrent administration of norethindrone with mestranol or ethinyl estradiol resulted in a significant increase in the fasting serum insulin concentration and the mean sigmal40. An increase in the mean K was also observed after norethindrone + mestranol. These results show that synthetic estrogens have the ability to potentiate the metabolic effects of norethindrone. However, the improvement in glucose tolerance produced in rhesus monkeys by concurrent mestranol + norethindrone treatment was marginal because of wide variation in glucose assimilation rates uncer control conditions. Thus, the IVGTT in the rhesus monkey appears to have limited use as a model for studying glucose homeostasis in man.

Administration, Oral↗
PubMed1987

Automated stability-indicating high-performance liquid chromatographic assay for ethinyl estradiol and (levo)norgestrel tablets.

An automated high-performance liquid chromatography (HPLC) assay for ethinyl estradiol and norgestrel or levonorgestrel in oral contraceptive tablets was developed. Tablets were prepared for on-line injection using a solid sampler and segmented continuous flow techniques. The active components were separated from tablet excipients, impurities, and degradation products on reversed-phase C8 and C18 columns by elution with water-acetonitrile-methanol (45:35:15). A UV detector connected in series with a fluorometric detector measured the UV absorbance of levonorgestrel and norgestrel at 240 nm and the fluorescence of ethinyl estradiol at 310 nm (excitation at 210 nm). The method employed computer control of the injection system and solid sampler for synchronization of the chromatographic and segmented flow streams. The method is applicable for content uniformity and stability testing at a rate of eight samples per hour.

Automation↗
PubMed1978

Double-blind crossover clinical pharmacology study comparing moxestrol (R 2858) and ethinyl estradiol in postmenopausal women.

The potency of 5 migrogram moxestrol (R 2858). 11beta-methoxy-17alpha-ethinyl-estra-1,3,5-[10]-triene-3,17-diol, administered orally, was compared to that of 25 microgram ethinyl estradiol in a double-blind crossover clinical pharmacology study of six postmenopausal women. At these doses, both compounds increased the eosinophilic index and decreased serum LH and FSH levels. A marked effect on circulating prolactin was observed only during ethinyl estradiol treatment.

Aged↗
PubMed1983

Pharmacodynamic effects of ethinyl estradiol in women using vaginal devices releasing small doses of levonorgestrel at a constant rate.

Eight normally menstruating women were provided with vaginal devices releasing levonorgestrel (NOG)4) at a constant rate of 20 micrograms/24 h. On day 71 or 72 following the insertion of the device, oral doses of 50 micrograms of ethinyl estradiol (EE) were administered daily for one week. Peripheral blood samples were drawn three times weekly during a pretreatment (control) cycle and from day 29 of the treatment period. The levels of progesterone (P), estradiol (E2) and NOG were measured by radioimmunoassay, sex hormone binding globulin (SHBG) by a steady state polyacrylamide gel electrophoresis and the percentage of binding of NOG, testosterone (T) and E2 by equilibrium dialysis of diluted plasma. An endometrial smear and a biopsy were taken from each subject on 3 occasions, viz. during the control cycle (cycle day 20-22), during the period with the NOG-releasing device in situ (44-50 days after the insertion of the device), and on the 7th day of concomitant EE administration.

Adult↗
PubMed1987

Determination of norgestimate and ethinyl estradiol in tablets by high-performance liquid chromatography.

A rapid, simple, stability-indicating assay procedure for norgestimate [(+)-13-ethyl-17-hydroxy-18,19-dinor-17 alpha-pregn-4-en-20-yn-3-one oxime acetate], a new progestational agent, and ethinyl estradiol (19-nor-17 alpha-pregna-1,3,5(10)-trien-20-yne-3,17-diol) in single- and composite-tablet analyses was developed using high-performance liquid chromatography. Norgestimate and ethinyl estradiol were extracted from the tablet matrix with methanol containing an internal standard. An aliquot was chromatographed on a 5-microns, reversed-phase column using water:tetrahydrofuran:methanol solution (65:25:10 v/v/v) as the mobile phase. The selectivity of the chromatographic system for intact norgestimate and ethinyl estradiol was demonstrated by resolving both compounds from various potential degradation products of each compound. An essential property of the chromatographic system was its ability to separate norgestimate as its syn and anti isomers. The method is linear, quantitative, and reproducible.

Drug Stability↗
PubMed1987

Modulation of Na+-H+ exchange by ethinyl estradiol in rat colonic brush-border membrane vesicles.

Prior studies by our laboratory have suggested that a relationship may exist between rat colonic brush-border membrane vesicular fluidity and Na+-H+ exchange. To further explore this possible relationship, in the present studies the effects of ethinyl estradiol (17 alpha-ethinyl-1,3,5-estratriene-3,17-beta-diol) administration subcutaneously (5 mg/kg body wt. per day) for 5 days, on rat colonic brush-border membrane fluidity and Na+-H+ exchange were examined. This treatment regimen has previously been shown to decrease the lipid fluidity of rat hepatic and rabbit small intestinal plasma membranes. In agreement with these prior studies, the present results demonstrate that this agent decreases the lipid fluidity of treated-rat colonic brush-border membranes compared to control membranes, as assessed by steady-state fluorescence polarization techniques using three different fluorophores. An increase in the cholesterol content and cholesterol/phospholipid molar ratio of treated-membranes appear to, at least partially, be responsible for the fluidity differences. Furthermore, examination of the kinetic parameters for amiloride-sensitive sodium-stimulated proton efflux in treated and control membrane vesicles, utilizing the pH-sensitive fluorescent dye, Acridine orange, revealed that ethinyl estradiol administration decreased the Vmax for this exchange mechanism, expressed in arbitrary fluorescence units, by approx. 25% but did not influence its Km for sodium. These data, therefore, lend further support to the contention that alterations in fluidity may modulate Na+-H+ exchange in rat colonic brush-border membrane vesicles.

Animals↗