A new HPLC-method for the separation of medium polar and nonpolar compounds in preparations of Valeriana officinalis was established for stability control. Powdered valerian root and a commercial ethanolic valerian extract were investigated for apparent differences in stability behaviour. Storage conditions were chosen according to the ICH-guidelines. Changes in composition of valerenic acids and lignans were observed depending on storage conditions and packaging materials. Hydroxyvalerenic acid, pinoresinol and hydroxypinoresinol were identified as degradation products in Valerian root, especially during accelerated testing. Ethanolic extracts appeared not to be as sensitive for chemical degradation under climatic influences compared to the crude plant material, and showed no increase in the amounts of lignan-aglyka. In comparison, extracts showed high sensitivity on changes of physical properties like loss on drying and viscosity
