Practical considerations when designing and conducting clinical pharmacokinetic herb–drug interaction studies

Abstract

Pharmacokinetic herb–drug interaction (HDI) research has been ongoing for almost two decades and a significant body of information has been published on the subject, yet much of it is contradictory. Some of this disparity stems from the botanical dosage form itself, as product quality and dosage form performance can vary significantly among brands. Unless products are adequately characterized, HDI study results can be misleading. The purpose of this report is to identify several common weaknesses inherent in many prospective clinical HDI studies and to provide guidance in addressing these shortcomings. Topics such as study design, pharmacokinetic end points, product quality, dosage form performance, gauging clinical relevance, and efforts to minimize dietary influences while improving compliance are discussed.