Current regulatory toxicology perspectives on the development of herbal medicines to prescription drug products in the United States

Toxicological studies constitute an essential part of the effort in developing an herbal medicine into a drug product. The US food and drug administration (FDA) published a guidance to assist academic and industry sponsors in the development of this unique group of drug products, and has recently approved an new drug application (NDA) based on green tea extract (Veregen) for topical treatment of genital and perianal warts. In this article, current regulatory views on issues related to requirements and recommendations on various types of nonclinical toxicity studies in support of clinical trials and filing an NDA for a herbal medicine, including pharm/tox aspects of green tea extract (Veregen) NDA, are discussed. Topics include nonclinical pharmacology/toxicology perspectives on herbal nomenclature and its identification, previous human experience and initial clinical trial proposal, regulatory aspects of acute toxicity studies, chronic toxicity studies, mutagenicity studies, reproductive toxicity studies, and carcinogenicity studies on botanicals. Certain regulatory review-related issues are also presented. It is anticipated that through a proactive two-way communication between the Agency and the sponsor, toxicological development of botanical drug product can be significantly facilitated.