Interaction study between antiplatelet agents, anticoagulants, diabetic therapy and a novel delivery form of quercetin

BACKGROUND: In this pilot non-interference clinical study we evaluated possible interactions between Quercetin Phytosome® (Quercefit™), an innovative delivery form of quercetin, and antiplatelet agents, anticoagulants, and anti-diabetic therapy in otherwise healthy subjects. METHODS: Interaction with antiplatelet therapy was assessed through the bleeding time (BT) test in 30 patients treated with acetylsalicylic acid, ticlopidine or clopidogrel before and after 10 days of supplementation with Quercetin Phytosome®. Interaction with anticoagulants was evaluated by measuring the International Normalized Ratio (INR) in 20 patients using warfarin or dabigatran before and after 20 days of supplementation with Quercetin Phytosome®. Lastly, glycaemia and glycated hemoglobin were measured in 12 diabetic patients treated with metformin and restricted diet before and after 20 days of supplementation with Quercetin Phytosome®. RESULTS: After 10 days of supplementation no significant difference was observed in mean BT in patients treated with acetylsalicylic acid, ticlopidine or clopidogrel at standard dosages. Similarly, after 20 days of supplementation, the INRlevel among patients assuming warfarin or dabigatran was not statistically different from baseline. Lastly, no statistically significant difference in mean levels of glycaemia and glycated hemoglobin was reported before and after 20 days of complementary administration of Quercetin Phytosome® in diabetic patients treated with metformin and restricted diet. CONCLUSIONS: Quercetin Phytosome® does not alter the antiplatelet activity of the most common antiplatelet agents, has no impact on the INR values in stable patients treated with warfarin or dabigatran, and does not influence the metabolic control of diabetic patient treated with metformin.