Binding of quinine- and sulfamethoxazole-specific DDABs to platelets is enhanced by using drug at supratherapeutic concentrations. Reactions of quinine-specific (A) and sulfamethoxazole-specific (B) DDAbs used at dilutions of 1:5 and higher to normal platelets were enhanced by using the drugs at supratherapeutic concentrations. Binding of patient Ig to platelets was measured by flow cytometry. MFI indicates median platelet fluorescence; values on the abscissa indicate final concentration of drug in the reaction mixture. Vertical lines denote expected mean peak levels achieved after administration of a conventional dose of quinine (10μM) and sulfamethoxazole (80μM).^12,13