The Azosulfamide (Neoprontosil) Test in Clinical Evaluation of Liver Function

Abstract

In 1951, Siede and Strohm ¹ suggested a liver-function test with a sulfonamide preparation, the red dye azosulfamide (Prontosil Soluble, Bayer, or Neoprontosil, Winthrop). Azosulfamide is a sodium salt of an azo compound between sulfanilamide and a hydroxynaphthaline sulfonic acid with the formula shown in Figure 1. About one-half of the administered dose is taken up by the liver cells. Part of this is then excreted unchanged in the bile,² whereas the rest is broken down, probably by reductive enzymes.³ One of the metabolites seems to be sulfanilamide.⁴ The remainder of the azosulfamide, i. e., the part not removed by the liver, is excreted unchanged in the urine. The elimination occurs chiefly during the first 5 to 6 hours after the injection and is completed within 24 hours. The total amount of azosulfamide eliminated in the urine gives an indirect measure of the liver function with regard