Concurrent administration of anticancer chemotherapy drug and herbal medicine on the perspective of pharmacokinetics

With an increasing number of cancer patients seeking an improved quality of life, complementary and alternative therapies are becoming more common ways to achieve such improvements. The potential risks of concurrent administration are serious and must be addressed. However, comprehensive evidence for the risks and benefits of combining anticancer drugs with traditional herbs is rare. Pharmacokinetic investigations are an efficient way to understand the influence of concomitant remedies. Therefore, this study aimed to collect the results of pharmacokinetic studies relating to the concurrent use of cancer chemotherapy and complementary and alternative therapies. According to the National Health Insurance (NHI) database in Taiwan and several publications, the three most commonly prescribed formulations for cancer patients are Xiang-Sha-Liu-Jun-Zi-Tang, Jia-Wei-Xiao-Yao-San and Bu-Zhong-Yi-Qi-Tang. The three most commonly prescribed single herbs for cancer patients are Hedyotis diffusa, Scutellaria barbata, and Astragalus membranaceus. Few studies have discussed herb–drug interactions involving these herbs from a pharmacokinetics perspective. Here, we reviewed Jia-Wei-Xiao-Yao-San, Long-Dan-Xie-Gan-Tang, Curcuma longa and milk thistle to provide information based on pharmacokinetic evidence for healthcare professionals to use in educating patients about the risks of the concomitant use of various remedies.