Formation of 7&agr;-methyl-ethinyl estradiol during treatment with tibolone

@article{Wiegratz2002FormationO7,
  title={Formation of 7\&agr;-methyl-ethinyl estradiol during treatment with tibolone},
  author={I. Wiegratz and N. S{\"a}nger and H. Kuhl},
  journal={Menopause},
  year={2002},
  volume={9},
  pages={293-295}
}
ObjectiveTo investigate whether tibolone, which is orally used for hormone replacement therapy, is transformed to a derivative of ethinyl estradiol (EE). DesignIn 10 young women who received 2.5 mg orally administered tibolone daily between cycle day 19 and 25, blood was obtained before and 0.5, 1, 1.5, 2, 3, 4, 6, 8, and 24 h after the last tablet intake. The concentration of 7&agr;-methyl-EE was determined by the gas chromatography with mass spectrometry method. ResultsThe results demonstrate… Expand
7&agr;-Methyl-ethinyl estradiol is not a metabolite of tibolone but a chemical stress artifact
TLDR
7&agr;-MEE is not a metabolite of tibolone but is a chemical artifact generated during analytical procedures with derivatization, and cannot be demonstrated in plasma from postmenopausal women after single or multiple doses of tIBolone. Expand
Estrogenic effects of 7α-methyl-17α-ethynylestradiol: a newly discovered tibolone metabolite
Abstract Tibolone is a synthetic steroid that is prescribed to postmenopausal women for relief of climacteric symptoms and prevention of osteoporosis. It has been reported to be metabolized in aExpand
Conversion of tibolone to 7&agr;-methyl-ethinyl estradiol using gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry: interpretation and clinical implications
TLDR
The findings prove that conversion of tibolone to MEE is an artifact that is generated in a GC- MS system and is largely due to the intense heating step involved in GC-MS. Expand
Tibolone is not aromatized in postmenopausal women
  • H. Kloosterboer
  • Medicine
  • Climacteric : the journal of the International Menopause Society
  • 2008
TLDR
The conclusions of the study were that the THEBES results confirm previous findings that tibolone does not induce endometrial hyperplasia or carcinoma in postmenopausal women, and it is associated with a better vaginal bleeding profile than conjugated equine estrogens/medroxyprogesterone acetate. Expand
Lack of aromatisation of the 3-keto-4-ene metabolite of tibolone to an estrogenic derivative
TLDR
7alpha-methyl norethisterone does not undergo aromatisation to an estrogenic derivative, and radioactivity detected on the TLC plate or HPLC fractions revealed that similar levels were present when 7alpha- methyl norehisterone was incubated with culture medium alone or with JEG-3 cells in the absence or presence of letrozole. Expand
Can 19-nortestosterone derivatives be aromatized in the liver of adult humans? Are there clinical implications?
  • H. Kuhl, I. Wiegratz
  • Medicine
  • Climacteric : the journal of the International Menopause Society
  • 2007
TLDR
19-nortestosterone derivatives (norethisterone, norethynodrel, tibolone) can readily be aromatized in the adult human liver, which leads to the formation of the potent estrogens ethinylestradiol from norehisterone or nore fourthodrel and 7α-methyl-ethinylest radiol from tibiaolone. Expand
Tibolone is not converted by human aromatase to 7α-methyl-17α-ethynylestradiol (7α-MEE): Analyses with sensitive bioassays for estrogens and androgens and with LC-MSMS
To exclude that aromatization plays a role in the estrogenic activity of tibolone, we studied the effect tibolone and metabolites on the aromatization of androstenedione and the aromatization ofExpand
Tissue-selectivity: the mechanism of action of tibolone.
TLDR
Tibolone appears to regulate estrogenic activity in the various tissues by influencing the availability of estrogenic compounds for the estradiol receptor in a tissue-selective manner and has direct oestrogenic effects on the cardiovascular system. Expand
[Effect of tibolone on endometrium of castrated rats].
TLDR
High doses of tibolone, given for long periods of time to castrated female rats, have an estrogenic effect which can be dose-dependent, causing proliferation in the endometrium and causing changes in the cell differentiation (squamous metaplasia), but do not lead to hyperplasia. Expand
Regulation of activities of steroid hormone receptors by tibolone and its primary metabolites
TLDR
Tibolone by these actions on different receptors and by this capacity to transform in different metabolites, has more complex effects than initially supposed. Expand
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Estrogenic effects of 7α-methyl-17α-ethynylestradiol: a newly discovered tibolone metabolite
Abstract Tibolone is a synthetic steroid that is prescribed to postmenopausal women for relief of climacteric symptoms and prevention of osteoporosis. It has been reported to be metabolized in aExpand
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