Prohemorrhagic potential of dipyrone, ibuprofen, ketorolac, and aspirin: Mechanisms associated with blood flow and erythrocyte deformability

Dipyrone, ibuprofen, ketorolac, and aspirin were tested in a well-defined p erfusion system (shear rates: 300/s, 800/s, and 1,800/s). Whole blood sampl es were treated with the drugs at analgesic doses and platelet interaction with damaged subendothelium was measured. All the drugs fully inhibited pla telet cyclooxygenase, as assessed by classic aggregometry. Perfusion studie s showed that there was a general tendency to reduce the percentage of larg e aggregates (thrombus; %T), to increase the percentage of adhered platelet s (adhesion; %A), and to reduce the height of thrombi with respect to contr ol. Aspirin significantly increased %A and reduced %T at all shear rates te sted, whereas dipyrone had the same effect at 800/s, and ketorolac and ibup rofen at 1,800/s. In addition, aspirin significantly reduced erythrocyte de formability with respect to the other drugs. In conclusion, under our exper imental conditions, aspirin showed the most remarkable effects on platelet function, closely followed by dipyrone. The effects of ketorolac were moder ate, whereas ibuprofen had a minor impact on platelet function.