THE OCCURRENCE OF METHEMOGLOBINEMIA DURING SULFANILAMIDE THERAPY

Abstract

The Hardy recording photoelectric spectrophotometer was used to provide objective, accurate measurements of the colored components of the blood of patients receiving sulfanilamide. Curves drawn by this instrument are reproduced with the absorption coefficients of Hb, methemoglobin (MHb), and the colored oxidized forms of sulfanilamide. Curves of patients'' blood are shown with a prominent deviation at 630 [mu] characteristic of MHb. Another curve represents the result of the in vitro formation of over 90% MHb from a soln. of Hb by sulfanilamide that previously had been oxidized with ultraviolet light to the blue derivative. This curve shows the presence of a 3d colored component which is identified by computations based on Beer''s and Bouguer''s laws as the reduced form of the blue oxidant used. Similar calculations with the data of the curves of patients'' blood indicate in addition to Hb and MHb, the presence of a 3d colored component with similar spectral characteristics best noted from 660 [mu] to 700 [mu]. The methemoglobinemia of sulfanilamide therapy is interpreted as resulting from the in vivo oxidation of sulfanilamide to the blue derivative which in turn oxidizes Hb to MHb and is itself reversibly reduced.