[Radiocompetitive assay of sulfamido-3-chloro-4-benzoic acid with carbonic anhydrase as binding reagent (author's transl)]. / Dosage d'un sulfamide diurétique, l'Acide sulfamido-3-chloro-4-benzoique, par radiocompetition avec l'anhydrase carbonique.

The control of patients treated by diuretic sulfonamides can be carried out by a radiocompetitive assay using their binding properties to carbonic anhydrase (CA). In this paper we have studied the assay of sulfamido-3-chloro-4-benzoic acid (SD3) using dialysis equilibrium as separation procedure. With (CA) 2 X 10(-6) M and 14C-SD3 0.5 X 10(-6) M (specific activity: 2 muCi/mg), can be detected 0.5 X 10(-6) M of (SD3) in the assay medium. 6.5 mg protein present in serum lower the assay sensitivity twenty times, owing to an elevated value of the affinity constant, Ka, of albumin-(SD3) complex (10(3) mol-1). On the other hand, the molecules with sulfamidobenzoic group cannot be differentiated in this procedure.

Pharmacokinetics and metabolism of 14C-glipentide, a new antidiabetic, after oral and intravenous administration.

The pharmacokinetic study of 14C-glipentide in male Wistar rats shows, at 0.2 mg/kg doses, that blood radioactivity drops quickly. The metabolization is effected in the liver and leads to four labelled metabolites which are eliminated mainly by the bile. The physiological disposition of unchanged glipentide can be described by a two-compartment open model. Autoradiography and quantitative studies have shown that the liver presents the highest concentration of radioactivity, that diminishes to a very low value 96 h after the administration. In the other tissues the radioactivity is never large, even following repeated administrations. The plasma protein binding does not change with the time, and it can be presumed that binding forces of glipentide and its metabolites to plasma proteins are similar. Glipentide is very well absorbed. The urinary and fecal elimination of radioactivity is similar after oral and i.v. administration.