Radioreceptor assay for determination of the anti-progestogen, RU-486 and its active metabolites in the blood
Földesi, I.; Falkay, G.; Kovács, L.
Acta Pharmaceutica Hungarica 62(6): 271-277
1992
ISSN/ISBN: 0001-6659 PMID: 1488912 Document Number: 393830
RU-486 is an antiprogesterone 19-norsteroid with high binding affinity for the progesterone receptor. It can be used with success for termination of early human pregnancy. Since the metabolites of RU-486 are often biologically active, their concentrations in blood can also have clinical significance. We have developed a rapid sensitive radio receptor assay for determination of RU-486 and its active metabolites. Human myometrium progesterone receptor was used as binding protein. The assay is based on the competitive replacement of 3H-ORG-2058 by the active molecular fraction of RU-486 present in the serum. The analytical parameters of this assay are the followings: intraassay percent of coefficient of variation (CV%) is ranged between 7.6 and 10.4%. The interassay CV% was from 7.1 to 16.3. The sensitivity of the receptor assay was 8.7 pmol/tube and the acceptable range was between 10 and 120 pmol/tube. The recovery ranged between 95 and 122% (r = 0.983). These parameters are suitable for the requirement of radioligand binding techniques based on the immunoassays.