In Vitro Effect of Dexmedetomidine on Platelet Aggregation

Background and objectives: Dexmedetomidine is a selective alpha(2)-agonist. There are 250-300 alpha(2)-agonist-adrenoceptor on the surface of each human platelet and ephedrine induces platelet aggregation by binding these receptors. This study was designed to study platelet function after incubation with therapeutic concentrations of dexmedetomidine. Methods: The study was carried out on 18 healthy, non-smoking males, ages ranging 25 to 35 years old. Because of the recommended therapeutic concentration range of dexmedetomidine obtained by intravenous infusion is 0.4-1.2 ng.mL(-1), dexmedetomidine solutions were prepared in three different concentrations. The calculated value of dexmedetomidine solution and diluent without dexmedetomidine as control were added to the blood sample. Thus, we obtained 0, 0.4, 0.8 and 1.2 ng.mL(-1) dexmedetomidine concentrations of plasma. Each concentration of dexmedetomidine was incubated with whole blood at 37 degrees C during 15 minutes. Then blood samples were centrifugated to prepare platelet-rich plasma and platelet-poor plasma. The platelet-rich plasma was diluted with the platelet-poor plasma to yield test platelet-rich plasma with a final platelet count of 250 +/- 50 X 10(9).L-1. Results: The platelet aggregation amplitudes and slopes were statistically similar among all groups by the aggregation test, which were performed with ADP, collagen or epinephrine. Conclusion: Therapeutic concentrations of dexmedetomidine had no effect on the platelet functions in healthy individuals in vitro. (C) 2013 Sociedade Brasileira de Anestesiologia. Published by Elsevier Editora Ltda. All rights reserved.