Extract as a Modern Dosage Form for Natural Drugs
a Department of Pharmacognosy and Botany, University of Veterinary Medicine and Pharmacy, Košice, Slovakia, b Department of Pharmaceutics, Faculty of Pharmacy, Veterinary and Pharmaceutical University, Brno
Keywords: plant extracts, extraction techniques, natural products
Plant extracts still constitute a part of commonly used dosage forms, but they can also be understood as raw materials for pharmaceutical industry. The production of extracts is based on the periodic, continuous and semi-continuous methods, which can also be classified as conventional extraction methods (maceration, percolation, infusion, decoction, distillation, Soxhlet extraction, ultrasound assisted extraction and headspace extraction) or modern extraction methods (supercritical fluid extraction, pressurized liquid extraction, microwave assisted extraction, solid phase micro extraction, stir bar sorptive extraction, matrix solid phase dispersion, quick easy cheap rugged effective and safe extraction). The extraction-method efficiency depends on the characteristics of the extracted material (e.g. particle size, ballast materials, thickness of the cell wall), physical factors (e.g. temperature, pressure, microwave, ultrasound), the extraction time, mixing (it influences the concentration gradient), solvent type and the presence of cosolvent. For environmental reasons, it is suitable to produce the extracts by using certain gases in supercritical conditions as solvents (e.g. carbon dioxide, nitrogen) or other generally recognized as safe solvents (e.g. water, propylene glycol) that provide a high yield at a correct methodology.
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