Steroid contraceptives in non-human primates (II) Metabolic fate of synthetic estrogens in the baboon exposure to oral contraceptives
1977; Elsevier BV; Volume: 15; Issue: 3 Linguagem: Inglês
10.1016/0010-7824(77)90116-0
ISSN1879-0518
AutoresB.D. Kulkarni, T.D. Avila, James A. O’Leary,
Tópico(s)Estrogen and related hormone effects
ResumoThe metabolic fate of isotopically labelled ethynylestradiol (EE) and its 3-methyl ether, mestranol (MEE), was investigated in three baboons who were receiving a norethindrone-mestranol combination oral contraceptive (C.O.C.) and the results compared to those previously obtained from the same baboons before receiving the C.O.C. The mean urinary excretion of radioactivity within 6 days following the administration of 3H-EE and 14C-MEE ranged from 38.3 to 40.8% and 17.8 to 19.8% of the dose, respectively. The plasma levels of 3H-EE at various time intervals during the first-half of the cycle, corresponding to the follicular phase, did not appear to differ significantly from those during the second-half of the cycle, corresponding to the luteal phase. The plasma 3H-EE levels at the end of 24 hours remained more than 7% of the dose, a value several times higher than that observed during the same time interval before the baboons received the C.O.C. The 14C-MEE levels, however, circulating at the end of 24 hours appears to be almost the same whether or not the baboons received the C.O.C. These observations suggest that orally administered MEE is demethylated to EE in primates.
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