To the Editor:
—Since the article in the March number entitled "Effect of Inflammation on the Concentration of Sulfanilamide in Pleural and Joint Fluids" by Raymond Gregory (Arch. Int. Med.69:429, 1942) leads to some rather startling conclusions, I should like to make a few comments on it.It is difficult to understand how a freely diffusible substance like sulfanilamide would concentrate in a purulent effusion. Dr. Perrin Long several years ago made the same—and to him startling—discovery that the level of the drug in the body fluid was extremely high in relation to its level in the blood stream. However, a little further investigation soon revealed that the apparently high level in the body fluid was due to the procaine hydrochloride used for local anesthesia during withdrawal of the fluid. Many persons erroneously assume that because a method is described for the determination of sulfanilamide it is necessarily specific.