GESTODENE AND DESOGESTREL DO NOT HAVE A DIFFERENT INFLUENCE ON CONCENTRATION PROFILES OF ETHINYLESTRADIOL IN WOMEN TAKING ORAL-CONTRACEPTIVES - RESULTS OF ISOTOPE-DILUTION MASS-SPECTROMETRY MEASUREMENTS
L. Siekmann et al., GESTODENE AND DESOGESTREL DO NOT HAVE A DIFFERENT INFLUENCE ON CONCENTRATION PROFILES OF ETHINYLESTRADIOL IN WOMEN TAKING ORAL-CONTRACEPTIVES - RESULTS OF ISOTOPE-DILUTION MASS-SPECTROMETRY MEASUREMENTS, European journal of endocrinology, 139(2), 1998, pp. 167-177
Objectives: A new method for the quantitative determination of 17 alph
a-ethinylestradiol-17 beta (EE2) in serum is presented here based on t
he principle of isotope dilution mass spectrometry (IDMS) with [C-13]E
E2 as internal standard, The technique was used to determine the conce
ntration profiles of EE2 in the serum of female subjects who had tal;e
n oral contraceptives with different progestin components. The method
has proved to be very reliable with respect to trueness, specificity p
recision and detection sensitivity and offers considerable advantages
compared with the immunological methods of measurement used to date. S
tudy design: Forty-seven female volunteers took two different oral con
traceptives containing EE2 combined with different progestins in accor
dance with a cross-over design, After the administration of 30 mu g EE
2 combined with 75 mu g gestodene (EE2/GSD) or 150 mu g desogestrel (E
E2/DES), blood samples were taken from the subjects on certain days an
d in certain previously specified cycles in the course of 12 h after m
edication. Results and conclusions: The biometric analysis of the resu
lts showed that the concentration profiles of EE2 were, in their stati
stics, significantly equivalent after the administration of either of
the two oral contraceptives. The sometimes contradictory results found
in former studies after the administration of the different contracep
tives were presumably due to the methodological shortcomings of the ra
dioimmunological measurement technique. With the use of the highly acc
urate and specific technique of IDMS it can now be unequivocally estab
lished that the different progestins in the tested oral contraceptives
have no influence on the bioavailability of EEL (area under EE2 serum
concentration curves, as usually defined in pharmacokinetics).