Desmopressin effect on acetylsalicylic acid impaired platelet function.

The mechanism of DDAVP's shortening of acetylsalicylic acid (ASA) prolonged bleeding times was investigated. Sixteen healthy subjects received two dosages of ASA (100 mg) in 12 hours. Twenty four hours after the first ASA application and again after 32 hours DDAVP was administered intravenously (0.4 micrograms/kg). The trial was terminated after 48 hrs. In between, blood samples were drawn and analyzed for the in vivo bleeding time (Simplate time), in vitro bleeding test (IVBT, Thrombostat 4000), von Willebrand factor antigen (vWf:Ag), Ristocetin cofactor activity (vWf R:Co), plasma beta-thromboglobulin (beta-TG), platelet ATP/ADP, platelet aggregation (collagen, ADP, arachidonic acid), and plasma and platelet thromboxane levels. Simplate time (BT) and IVBT showed an excellent inverse correlation with vWf R:Co (r2 BT = 0.97 and r2 IVBT = 0.99, respectively) during the time when DDAVP was administered, suggesting the involvement of plasma vWF in DDAVP's shortening of the bleeding time. The involvement of plasma thromboxane in this mechanism could be excluded. In addition, DDAVP hampered platelet aggregation tests, possibly due to the inhibition of the release reaction (reduced beta-TG in plasma) by a direct interaction with platelets.