DETERMINATION OF A NEW HYPOGLYCEMIC DRUG, GLICLAZIDE, IN HUMAN SERUM BY RADIOIMMUNOASSAY

Radioimmunoassays have been developed which enable accurate and sensitive determination of gliclazide in human serum. Antisera A and B against gliclazide were obtained from guinea pigs immunized with conjugates A and B prepared by coupling gliclazide homologues, 1-(p-toluenesulfonyl)-3-(4'-carboxypiperidino) urea and 1-(4-methyl-3-carboxybenzenesulfonyl)-3-(3-azabicyclo [3, 3, 0] oct-3-yl) urea, to bovine serum albumin. 3H-Gliclazide was used as a tracer. Dextran-coated charcoal was used to separate bound and free 3H-gliclazide in the reaction mixture. The assays of gliclazide in serum were possible over a concentration range from 0.25 to 20 μg/ml with the antiserum A and from 0.1 to 10 μg/ml with the antiserum B, respectively, using 0.01ml of human serum without the need for an extraction procedure. The antisera used for the assays were specific for gliclazide. Data obtained by the radioimmunoassay with the antiserum A are in good agreement with those by the radioimmunoassay with the antiserum B and gas-liquid chromatography. Serum levels of gliclazide in healthy volunteers receiving single oral dosing (40 mg/subject) have also been determined.