Storage of Crude Drugs
Storage of crude drugs needs sound knowledge of their physical and chemical properties. The good quality of the drugs can be maintained if they are preserved properly. All the drugs should be preserved in well-closed and, possibly in the filled containers. They should be stored in the premises which are water-proof, fireproof and rodentproof. Several drugs absorb moisture during their storage and become susceptible to microbial growth. Some drugs absorb moisture to the extent of 25% of their weight. The moisture, not only increases the bulk of the drug but also causes impairment in the quality of the crude drug. The excessive moisture facilitates enzymatic reactions resulting in the decomposition of active constituents e.g. digitalis leaves and wild cherry bark. Gentian and ergot receive mold infestation due to excessive moisture. Radiation due to direct sun-light also destroys active chemical constituents, e.g. ergot, cod liver oil, and digitalis. The form or shape of the drug also plays a very important role in preserving the crude drugs. Colophony in the entire form (big masses) is preserved nicely, but if stored in powdered form, it gets oxidized or loses solubility in petroleum ether. Squill, when stored in powdered form becomes hygroscopic and forms rubbery mass on prolonged exposure to air. The fixed oil in the powdered ergot becomes rancid on storage. To maintain a good quality of ergot, it is required that the drug should be defatted with lipid solvent before storage. Lard, the purified internal fat of the abdomen of the hog, is to be preserved against rancidity by adding siam benzoin. Atmospheric oxygen is also destructive to several drugs and hence, they are filled in well-closed containers, or the air in the container is replaced by an inert gas like nitrogen; e.g. shark liver oil, papain, etc.
Apart from protection against adverse physical and chemical changes, preservation against insect or mold attacks is also important. Different types of insects, nematodes, worms, molds, and mites infest the crude drugs during storage. Some of the more important pests found in drugs are Coleoptera (Stegobium panicum and Calandrum granarium), Lepidoptera (Ephestia kuehniella and Tinea pellionella), and Arachnida or mites (Tyroglyphus farinae and Glyophagus domesticus). They can be prevented by drying the drug thoroughly before storage and also by giving treatment of fumigants. The common fumigants used for the storage of crude drugs are methyl bromide, carbon disulfide, and hydrocyanic acid. At times, drugs are given special treatment, such as liming of the ginger and coating of the nutmeg. Temperature is also a very important factor in the preservation of the drugs, as it accelerates several chemical reactions leading to the decomposition of the constituents. Hence, most of the drugs need to be preserved at a very low temperature. The costly phytopharmaceuticals are required to be preserved at a refrigerated temperature in well-closed containers. Small quantities of crude drugs could be readily stored in airtight, moisture-proof, and lightproof containers such as tin, cans, covered metal tins, or amber glass containers. Wooden boxes and paper bags should not be used for the storage of crude drugs.
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