Recently a new sulfonamide compound, sulfamethoxypyridazine, has been introduced into clinical usage which differs in several respects from currently available preparations of this group of drugs.1 The new agent is promptly absorbed after oral administration, and the free form of the drug is very slowly excreted in the urine. This results in long-sustained high plasma concentrations of free drug with doses much lower than those required to attain similar concentrations with several other sulfonamide agents.
An important area of usage of sulfonamides is in the treatment of urinary tract infections. When they are employed for this purpose, some observers have stressed the value of high urinary concentrations of biologically active material, and this is a prominent characteristic of several sulfonamide derivatives currently available. With sulfamethoxypyridazine, however, urinary concentrations of free drug are low, often not exceeding the plasma concentration. to establish its clinical effectiveness, partic- Thus, while there are apparent