Bioavailability of dodeca-2E, 4E, 8E, 10E/Z-tetraenoic acid isobutylamides after oral administration in rats and distribution in various tissues

Background Preparations from Echinacea are among the best-selling phytopharmaceuticals worldwide and have been widely used for the treatment of common cold and various upper respiratory infections. The most relevant active principles of Echinacea extracts are alkamides, caffeic acid derivatives (CADs) and glycoproteins/polysaccharides [1]. The main alkamides in Echinacea preparations are the isomeric dodeca-2E,4E,8E,10E/Z-tetraenoic acid isobutylamides (''tetraenes''). Until now, a limited number of pharmacokinetic studies with alkamides have been reported, but no data exist about their distribution in tissues and transport through the blood-brain barrier (BBB). Therefore, we evaluated the pharmacokinetics of dodeca-2E,4E,8E,10E/Ztetraenoic acid isobutylamides after a single oral dose administration of 2.5 mg/kg in plasma as well as in liver and four different brain regions (hippocampus, cerebral cortex, striatum and cerebellum).