The Secretion of Sulfonamide Drugs in Gastric Juice *

Although the sulfonamide drugs are ubiquitously distributed throughout the entire body water, a property important for their wide chemotherapeutic value, quantitative differences do exist with regard to the concentrations attained in certain compartments of the extracellular fluid after equilibrium is established. Perhaps most striking is the failure of sulfathiazole to reach a concentration in the spinal fluid of more than one-third of that in the blood (Sadusk, Blake, and Seymour,"5 Strauss, Lowell, Taylor, and Finland,17 and others). The fact that cerebrospinal fluid may not be formed wholly by a process of diffusion presents the possibility that the concentrations of sulfonamides in secretory fluids may depend upon factors other than those operative in simple diffusion and may vary with each particular drug and with each particular secretory membrane. Some indirect evidence for this hypothesis is afforded by the fact that the epithelial cells of the renal tubules selectively reabsorb sulfonamides from the tubular urine in such a manner that the renal excretion of sulfanilamide, sulfathiazole, and sulfaguanidine is more rapid than that for sulfapyridine and sulfadiazine, and that the renal clearances of acetylated sulfonamides are uniformly higher than those for the corresponding free forms. More direct evidence that secretory activity may influence the concentration of sulfonamide drugs can be obtained from the gastric juice. Thus, Carryer and Ivy3 found in Pavlov-pouch dogs that the concentration of sulfanilamide was higher in the gastric juice than in the other digestive secretions examined, and peak concentrations approaching 50 mgm% were obtained. However, simultaneously