Integration of herbal medicine into modern medical practices: issues and prospects.

The integration of herbal medicine into modern medical practices including cancer treatments must take into account the interrelated issues of quality, safety, and efficacy. Quality is the paramount issue because it can affect the efficacy and/or safety of the herbal products being used. Current product quality ranges from very high to very low due to intrinsic, extrinsic, and regulatory factors. Intrinsically, species differences, organ specificity, diurnal and seasonal variations can affect the qualitative and quantitative accumulation of active chemical constituents in the source medicinal plants. Extrinsically, environmental factors; field collection methods such as cultivation, harvest, post-harvest transport and storage; manufacturing practices; inadvertent contamination and substitution; and intentional adulteration are contributing factors to the quality of herbal medicinal products. Source plant materials that are contaminated with microbes, microbial toxins, environmental pollutants, or heavy metals; or finished products that are adulterated with foreign toxic plants or synthetic pharmaceutical agents can lead to adverse events. Substandard source materials or finished products will yield therapeutically less effective agents. Herbal medicine quality can also be attributed to regulatory practices. In a number of countries, herbal medicines are unregulated, which has led to product quality differences. Product quality improvement may be achieved by implementing control measures from the point of medicinal plant procurement under good agricultural practices (GAPs) and the manufacture of the finished botanical products under good manufacturing practices (GMPs), plus post-marketing quality assurance surveillance. The lack of pharmacological and clinical data on the majority of herbal medicinal products is a major impediment to the integration of herbal medicines into conventional medical practices. For valid integration, pharmacological and especially, clinical studies, must be conducted on those plants lacking such data. Adverse events, including drug-herb interaction must also be monitored to promote a safe integration of efficacious herbal medicine into conventional medical practices.