A MICROTITER PLATE ASSAY FOR SULFONAMIDES

Sulfamethoxazole, sulfisoxazole, and sulfadiazine are sulfonamides use d in the treatment of several infectious diseases. Several studies hav e demonstrated that the amino substituent plays an important role in b oth the toxicity and the therapeutic effect of these drugs. In view of these findings, a rapid and convenient method of analysis would be us eful for monitoring selected patients receiving these drugs. With the increasing use of microtiter plate methodology in the clinical laborat ory, an assay based upon the Bratton-Marshall reaction with the amino substituent was adapted to the microtiter plate format. The results in dicate that the microtiter plate assay for sulfonamides retains the se nsitivity and linearity necessary for analysis of sulfonamides in biol ogical fluids at clinically relevant concentrations. The assay is simp le, rapid, convenient, and suitable for monitoring procedures where on ly the measurement of the active drug concentration is required.