Radioimmunoassay of norethindrone (17 alpha-ethynyl-17 beta-hydroxy-4-estren-3-one) and ethynyl-estradiol (17 alpha-ethynyl-1,3,5, (10)-estratien-3, 17 beta-diol). Application to human plasma determination of norethindrone after oral administration of this steroid.

ABSTRACT

The experiment conditions for the evaluation of Norethindrone (17 alpha-Ethynyl-17 beta-hydroxy-4-estren-3-one, NET) and Ethynyl-estradiol (17 alpha-ethynyl-1, 3, 5 (10) estratrien-3, 17 beta-diol, EE) by radioimmunoassay are described. A minimal quantity of 25 pg of these two steroids could be evaluated using different reduced metabolites of NET, very little cross reaction is observed with 200 pg of these metabolites. No effect was observed with estradiol for the EE-antiserum. The NET-antiserum was used to evaluate this steroid and ethynodiol diacetate after oral administration to female volunteers. Maximal values in the plasma (2-3% of the administered dose) was found between 1-3 h after administration and at 24 h a concentration of 0.1-0.3% still remained in the plasma.

ABSTRACT

PIP The experimental conditions for the measurement of norethindrone (NET) and ethinyl estradiol (EE) in human plasma by radioimmunoassay are described. 25 pg of NET or EE could be detected by utilizing reduced me tabolites of NET. Minimal cross reaction occurred with 200 pg of the reduced metabolites. There was no apparent effect of estradiol for the EE antiserum. NET and ethynodiol diacetate were evaluated by the NET antiserum. Maximum plasma values (2-3% of the dose) of the compounds were observed 1-3 hours after administration. At 24 hours, the concentrations of the steroids in plasma was .1-.3% of the administered dose.