gestodene and 6-beta-hydroxycortisol

The measurement of the urinary excretion ratio of 6 beta-hydroxycortisol (6 beta-OHC)/cortisol was used as a non-invasive method to investigate possible changes in the activity of drug-metabolizing enzymes in women receiving different oral contraceptive formulations for 1 up to 3 treatment cycles. The contraceptive preparations were either levonorgestrel, gestodene or cyproterone acetate, each in combination with ethinyl estradiol, or only the progestogens levonorgestrel or gestodene. There was either no or only a small decrease in the 6 beta-OHC/cortisol ratio. Thus, only a minor inhibitory effect, if any, can be ascribed to the investigated contraceptive steroids in vivo. Previously observed differences between selected contraceptive steroids in vitro were not observed in the same way in vivo. This may be due either to the absence of a marked inhibitory activity in vivo or to the insufficient sensitivity of the marker 6 beta-OHC/cortisol to detect these changes. Another possible reason may be the considerably higher drug concentrations used in the in vitro studies as compared to those present in the serum of women under oral contraceptive therapy.

Topics: Contraceptives, Oral; Contraceptives, Oral, Combined; Cyproterone Acetate; Estradiol Congeners; Ethinyl Estradiol; Female; Humans; Hydrocortisone; Levonorgestrel; Norpregnenes

A randomized controlled clinical trial was undertaken over a 6-month treatment period with two low-dose combined oral contraceptives (OC) to investigate whether the metabolism and elimination of ethinyl estradiol (EE2) is differently influenced by the two progestational components gestodene (G) and desogestrel (D), an issue which has been very controversial recently. The two formulations contained 30 micrograms EE2 each, together with either 75 micrograms G or 150 micrograms D. Of the 40 young women recruited for each formulation, 31 of each group were available for statistical evaluation. The pharmacokinetics of serum EE2 were studied on day 1, 10 and 21 of cycle 1, 3 and 6. There were no significant differences between the two groups in any cycle with respect to parameters measured. This was true for the distinct intracyclical rise in the mean EE2 serum levels from day 1 to day 10 and the smaller further increase between day 10 and day 21, with no change in this respect between the cycles studied. Respective changes were seen with regard to the area under the EE2 serum concentration curve up to 4 and 24 hours (AUC0-4 and AUC0-24), cmax and tmax of serum EE2. The estrogen-dependent corticoid-binding globulin (CBG) increased similarly in the two groups intracyclically and slightly also intercyclically at all times tested. Except for the first treatment cycle, urinary excretion of cortisol and 6 beta-hydroxycortisol displayed a tendency to lower values intracyclically as well as intercyclically, again with no differences between the two groups. Also, the 6 beta-hydroxycortisol-to-cortisol ratio was not different between the groups, showing a slight tendency to rise from about 4 at the beginning of the medication to around 5.5 at the end of the 6th treatment cycle in both groups. It is concluded that G and D as components of low-dose OCs exert comparable effects on the metabolism and elimination of EE2.. The question of whether the pharmacokinetics of ethinyl estradiol (EE2) is affected differently by the progestins in low-dose combined oral contraceptives containing gestodene or desogestrel was revisited. 80 randomly allocated women took 30 mcg EE2 and either 75 mcg gestodene or 150 mcg desogestrel for the first 21 days of each cycle for 6 months. Blood samples taken on days 1, 10, and 21 of the 1st, 3rd and 6th cycle, at frequent times for 24 hours after pill intake, were analyzed for EE2, corticosteroid binding globulin, cortisol and 6beta-hydroxycortisol. 31 women in each group completed the study. Minor side effects such as headache, breast tension, acne, and nausea occurred in each group; 1 subject dropped out because of headache, nausea, and hypermenorrhea and 1 because of a hematoma. No significant differences were seen in serum EE2 levels including the rise in mean EE2 on days 1-10, or the smaller rise between days 10-21, or the pharmacokinetic parameters Cmax, tmax, area under the curve (AUC) at 0-4 hours, or AUC at 0-24 hours. There was a maximal variation of 11% in intracyclical increases in serum EE2, but no change in intercyclical variations. There were also no significant differences between groups in the expected estrogen-induced increase in corticosteroid binding globulin. Urinary hydroxycortisol increased slightly over each cycle, somewhat more in the 1st cycle, and a bit more in the desogestrel cycles than in gestodene cycles, but not significantly. This study was contrasted in detail with the reports that prompted the controversy over pharmacokinetics of estradiol during intake of the involved combined pills. The import of the assays for cortisol metabolites is the fact that estradiol and cortisol are metabolized by the same liver cytochrome P450 isoenzyme.

Topics: Adult; Contraceptives, Oral, Combined; Desogestrel; Drug Interactions; Ethinyl Estradiol; Female; Humans; Hydrocortisone; Immunoenzyme Techniques; Longitudinal Studies; Norpregnenes; Radioimmunoassay; Time Factors; Transcortin

Single doses of ethynylestradiol (30 micrograms) were given alone and in combination with either gestodene (75 micrograms) or desogestrel (150 micrograms) to 10 healthy female volunteers. The doses of steroids were given both orally and by i.v. infusion over 5-7 minutes. Blood samples were taken at regular intervals over 24 hours. The area under the plasma concentration versus time curve (AUC) for oral EE2 alone was 867 +/- 338 pg/ml x h, for oral EE2 in the presence of gestodene it was 795 +/- 206 pg/ml x h and for oral EE2 in the presence of desogestrel it was 614 +/- 132 pg/ml x h. With either gestodene or desogestrel present, the AUC of EE2 was not significantly different from that found when EE2 was given alone. In addition, there was no significant difference between EE2 + gestodene and EE2 + desogestrel. Comparing the relative oral and iv doses, the bioavailability of EE2 (alone) was 59.0 +/- 13% (n = 6), for EE2 plus gestodene it was 62.1 +/- 10% and for EE2 in the presence of desogestrel it was 62.1 +/- 4.4%. The clearance of EE2 (alone) was 19.9 +/- 5.5 l/h and in the presence of gestodene it was 19.4 +/- 9.6 l/h. The clearance of EE2 in the presence of desogestrel appeared slightly greater at 27.7 +/- 8.9 l/h but none of these clearance values were significantly different from each other. The urinary excretion of 6-beta-hydroxy cortisol was similar after all 6 doses of EE2. These data strongly suggest that following single dose administration, neither gestodene nor desogestrel have any inhibitory effect on the metabolism of EE2 or alter its kinetics to any clinically significant extent.

Topics: Administration, Oral; Adult; Analysis of Variance; Biological Availability; Desogestrel; Drug Combinations; Drug Interactions; Ethinyl Estradiol; Female; Humans; Hydrocortisone; Infusions, Intravenous; Metabolic Clearance Rate; Norpregnenes; Progesterone Congeners; Radioimmunoassay

Predisposition to idiosyncratic toxicity with carbamazepine is thought to be due to a deficiency of the detoxication enzyme, microsomal epoxide hydrolase, although in some cases, concurrent administration of enzyme inducers might be a contributory risk factor, by altering the critical balance between bioactivation and detoxication. In this study, a mouse model has been used to determine the factors affecting carbamazepine bioactivation, using covalent binding and cytotoxicity as markers of bioactivation in vitro. Microsomes prepared from mice pre-treated with phenobarbitone increased (relative to the control microsomes) the formation of cytotoxic (12.3% vs 3.2%), protein-reactive (3.0% vs 2.0%) and stable (33.8% vs 18.1%) metabolites of carbamazepine. Similarly, pre-treatment with dexamethasone also increased the formation of the cytotoxic (24.8% vs 6.7%), protein-reactive (2.8% vs 1.5%) and stable (38% vs 19.8%) metabolites of carbamazepine, while beta-naphthoflavone pretreatment did not increase the formation of either the toxic or stable metabolites of carbamazepine when compared with its control microsomes. Co-incubation with gestodene (10-250 microM) resulted in a dose-dependent inhibition of both the bioactivation of carbamazepine and the formation of its stable 10,11-epoxide. SDS-PAGE and immunoblotting of the microsomes with anti-CYP3A antibody revealed the presence of a 52 kDa protein band in each preparation of microsomes, but the relative intensities of the bands, as measured by laser densitometry, were highest with the phenobarbitone and dexamethasone microsomes. The microsomal oxidation of cortisol to 6 beta-hydroxycortisol was also enhanced by pretreatment of mice with phenobarbitone (6.5% vs 2.7%) and dexamethasone (8.2% vs 4.3%), but not beta-naphthoflavone (2.2% vs 1.6%), when compared with their respective control microsomes, and was inhibited (range 25-68% inhibition), with all the microsomes by gestodene (50 microM). Taken collectively, the data in this study demonstrate that in the mouse, induction of the CYP3A subfamily significantly increases carbamazepine bioactivation. It is likely that in humans inducers of the orthologous form of this enzyme, most notably anticonvulsants, may increase the bioactivation of carbamazepine.

Topics: Animals; Benzoflavones; beta-Naphthoflavone; Biotransformation; Carbamazepine; Cytochrome P-450 Enzyme Inhibitors; Cytochrome P-450 Enzyme System; Dexamethasone; Enzyme Induction; Hydrocortisone; Immunoblotting; Male; Mice; Mice, Inbred CBA; Microsomes, Liver; Norpregnenes; Phenobarbital