Effect of the antihistaminic drug Bromadryl on ex vivo platelet functions during gestation in rats.

The effect of the antihistaminic drug Bromadryl on stimulated platelet aggregation was studied in pregnant rats. Bromadryl was administered orally in doses 1, 5 and 10 mg/kg from day 2 to day 19 of gestation. On day 20 of gestation blood samples were taken and the aggregation of platelets was measured after stimulation with 9 different concentrations of ADP in the concentration range 0.2 to 100 mumol/l. During gestation, platelet aggregation was significantly increased in comparison to non-pregnant controls. This was indicated in pregnant rats by the increased maximum amplitude of the aggregation curve as well as by the decreased mean effective concentration of ADP. The treatment of dams with Bromadryl during pregnancy resulted in decreased platelet aggregation. The dose-dependent inhibitory effect of the drug was more pronounced at higher stimulus concentrations. The presented results confirmed the antiplatelet activity of Bromadryl observed previously in vitro.