Pharmacokinetic profile of the isoflavone puerarin after acute and repeated administration of a novel kudzu extract to human volunteers

Objectives: This study was undertaken to assess the pharmacokinetic profile of puerarin, the major isoflavone found in a kudzu (Pueraria lobata) extract after acute and repeated administration. Methods: Participants were given either single or repeated doses of kudzu extract, and blood samples were collected for either 8 or 72 hours for subsequent pharmacokinetic analyses of puerarin. Results: Using WinNonlin pharmacokinetic data analysis software, puerarin was found to be rapidly absorbed via the oral route, reach peak levels at 2 hours, and have a half-life of approximately 4.3 hours. The elimination half-life was not significantly altered after repeated administration. Conclusions: A formulation of kudzu extract delivers a large amount of the principal isoflavone in a rapid manner. The elimination rate constants and the mono-exponential decline in blood levels suggest that a one compartment model adequately explains how puerarin is handled by the body. Three times a day dosing is recommended as accumulation will not occur, and plasma levels remain at levels that are biologically active, even 8 hours after the last steady-state dose.