The formulation of plant extracts into dosage forms is a complex operation which cannot be regarded only as a problem of pharmaceutical technology. "Extracts are liquid or solid or of intermediate consistency preparations obtained from vegetable raw materials, as a rule dried. Extracts are prepared by exhaustion with appropriate solvents, through maceration or percolation, or other suitable procedures, from drugs reduced to appropriate particle size. Purified extracts have an identity and validity of their own because they are natural mixtures of chemically related substances, all endowed with the same or similar pharmacological activity. The isolation from these natural mixtures of a particular constituent in the pure state may be pharmacological and economie nonsense, justified only in certain cases by the need for a single more easily identifiable principle, especially in studies of pharmacokinetics. Fluid, soft, or dry extracts may be used for preparing liquid dosage forms.