Effect of Salicis cortex extract on human platelet aggregation

The bark of Salix species contains several prodrugs of salicylate, mainly s alicin. The aim of this study was to investigate if during pain treatment w ith Salicis cortex extract platelet aggregation was affected. A total of 51 patients were enrolled in the study. Thirty-five patients suffering from a cute exacerbations of chronic low back pain received randomly and double-bl ind either Salicis cortex extract with 240 mg salicin/day (n = 19) or place bo (n = 16), Further sixteen patients with stable chronic ischemic heart di sease were given 100 mg acetylsalicylate per day, Platelet aggregation was studied using an aggregometer, As aggregating agents, arachidonic acid (500 mug/ml). adenosine di-phosphate (2 x 10(-5) M) and collagen (0.18 mug/ml) were used. The mean maximal arachidonic acid induced platelet aggregation w as 61%, 78% and 13% in the Salicis cortex extract, placebo and acetylsalicy late groups. Acetylsalicylate had a significant inhibitory effect on platel et aggregation compared to Salicis cortex extract (p = 0.001) and placebo ( p = 0.001). There was also a significant difference between the placebo and the willow bark-treated groups in the maximal platelet aggregation induced by arachidonic acid (p = 0.04) and ADP (p = 0.01), No statistical differen ce was found between the groups when collagen was applied to the human plat elets. Daily consumption of Salicis cortex extract with 240 mg salicin per day affects platelet aggregation to a far lesser extent than acetylsalicyla te. Further investigation needs to clarify if this finding is of clinical r elevance in patients with impaired thrombocyte function.