Effects of Penicillin G on Platelet Aggregation, Release, and Adherence to Collagen

Penicillin G (1000–8000 units/ml) inhibits ADP, collagen or thrombin-induced platelet aggregation and the release reaction in human PRP and in suspensions of washed platelets from rabbits or pigs. Adherence of washed platelets from all three species to a collagen-coated surface is also inhibited by penicillin G in this concentration range. Penicillin G may coat platelets, as it does red cells, block the sites where the aggregating agents interact with the platelets, and thus inhibit the response of platelets to them. Since these concentrations are achieved in vivo when massive penicillin therapy is used or penicillin is applied locally, these observations may be relevant to alterations of platelet function during such treatment.