RT Journal A1 MOLLERBERG HL, BĂ–TTIGER LE T1 THe azosulfamide (neoprontosil) test in clinical evaluation of liver function JF A.M.A. Archives of Internal Medicine JO A.M.A. Archives of Internal Medicine YR 1959 FD June 1 VO 103 IS 6 SP 949 OP 953 DO 10.1001/archinte.1959.00270060101012 UL http://dx.doi.org/10.1001/archinte.1959.00270060101012 AB 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.4The 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