Pharmacokinetic and pharmacodynamic interactions of Echinacea and policosanol with warfarin in healthy subjects - Mohammed Abdul, M I; Jiang, X; Williams, K M; Day, R; Roufogalis, B D; Liauw, W S; Xu, H; Matthias, A; Lehmann, R P; McLachlan, A J (Br J Clin Pharmacol, 2010)