Drug-dependent clearance of human platelets in NOD/scid mice is enhanced by supra-therapeutic concentrations of drug. Human platelets suspended in plasma containing DDAbs at the indicated dilutions were infused into NOD/scid mice followed by intraperitoneal injection of quinine (50 mg/kg; A) or sulfamethoxazole (250 mg/kg; B) at 0 and 5 hours. Platelet survival was markedly shortened in mice given DDAbs diluted 1:15 (squares) and 1:45 (triangles) followed by injection of the appropriate drug. Values shown are the average of triplicate experiments ± 1 SEM. **P < .01, ***P < .001 relative to controls.