Biopharmaceutical characterisation of herbal medicinal products: are in vivo studies necessary?

Herbal medicinal products have to meet comparable standards concerning the assessment of efficacy, safety and (bio)pharmaceutical quality as chemicall y defined synthetic drugs. However, these requirements are not fulfilled fo r many herbal products so far, particularly regarding in vitro dissolution and in vivo bioavailability. The necessity of in vivo studies for a biopharmaceutical characterisation o f the products depends on the solubility/permeability properties of the act ive drug ingredient as well as dissolution behaviour of the dosage form. Al so, in the case of herbal medicinal products, a waiver of in vivo BA/BE stu dies is recommended as long as the active ingredient is highly soluble acco rding to the Biopharmaceutics Classification System and dissolution of the dosage form takes place rapidly (>85%/20 min) in physiological buffer syste ms (pH 1-8).