Nafcillin-induced platelet dysfunction

Many drugs interfere with the normal hemostatic function of platelets. The largest number of reported cases of antibiotic-induced hemostatic defects is associated with carbenicillin and penicillin G. These hemostatic defects are identified primarily as platelet dysfunction with some cases resulting in clinical bleeding. Ampicillin, methicillin, oxacillin, cloxacillin, ticarcillin, cephalothin, and cefazolin show similar effects when these drugs are given to animals or humans prior to blood sampling for in vitro aggregation studies. This same dysfunction is thought to occur when normal platelet-rich plasma is spiked with these drugs prior to aggregation studies. The exact mechanism the effect on platelets is unknown. The objectives of this study were; 1.) To evaluate the effect of nafcillin on platelet aggregation and 2.) To investigate the effect of increasing concentrations of nafcillin on the aggregation response.