Time to peak effect of aspirin-induced platelet inhibition and ex vivo effects of desmopressin: An observational study

Objective: To investigate time to maximal platelet inhibition after an oral loading dose of ASA. The effect of ex vivo reversal platelet inhibition by desmopressin (DDAVP) was also studied. Methods: Ten healthy volunteers were given a 300 mg ASA-tablet. Blood was sampled at 0, 15, 30, 60, 120 and 180 minutes. DDAVP was added to the samples taken at 120 minutes. Samples were analysed with a Multiplate® platelet aggregometer (MEA) using arachidonic acid (AA), collagen and thrombin aggregation agonists. Results: Platelet inhibition was observed in the sample activated by AA at 15 minutes but not until 120 minutes in the samples activated by collagen. No platelet inhibition was seen in the samples activated by thrombin. The median time to maximal AA-induced platelet inhibition of <30 U was 30 (interquartile range 15-90) minutes. Ex vivo DDAVP did not reverse platelet inhibition. Subgroup analysis did not show any gender differences. Conclusions: ASA induces a strong platelet inhibition within 30 minutes of oral ingestion, with no gender differences. Ex vivo DDAVP did not reverse ASA’s platelet inhibition.