Crude drugs are the raw form of natural drugs derived from natural sources like plants, animals, or microbes.
As the name indicates crude mean in real form mean without modification so we can define crude drugs as follow,
The pure form of the drug collected from natural sources without human changes is known as a crude drug.
The only change in the crude drug may be the process of drying means after collection these are dried to protect from the microbial growth.
History
In the early days when no dosage form was developed the human being used to eat natural plants, herbs, or some parts of animals for treatment.Later on with evaluation of technology these crude drugs were used for manufacturing of different extracts of drugs and later on synthetic method was used to produce molecules similar to the crude drugs.
So the Study of crude drugs or pharmacognosy played an important role in development of modern drug dosage forms.
Identification Of Crude Drugs
Identification of crude drugs can be done by the following method,
Organoleptic Properties
Identification or evaluation of the crude drugs by organoleptic properties means to recognize the natural drugs by using natural senses like taste, touch, smell, sight etc.
As we know that crude drugs are natural drugs and most of them are from plants so these drugs are identified by using natural senses and help in the identification of a specific drug from a combination of different drugs.
It is also helpful for the collection of drugs because most drugs are easily identified by natural senses.
During the study, a pharmacognosist is provided with crude drugs to identify. Usually, a box containing crude drugs is present in the pharmacognosy lab and students are trained to identify different drugs based on size, shape, colour, smell etc.
Standard appearance and morphology of each drug are given in standard books and sometimes the colour or shape of a drug may vary from standard due to some variations in actual conditions.
For example, the colour of a drug may vary if it is exposed to sunlight.
Some crude drugs can easily be identified by the shape like clove and some have a sweet taste like glycyrrhiza and are identified by taste easily.
Evaluation Of Crude Drug
Evaluation is a broader term that is used to identify the drug and to check the activity of active constituents and their activity in crude drugs.The process of evaluation is also used to identify adulterants in the drugs.
For evaluation following are used,
Organoleptic Properties
Microscopic Study
Biological Study
Chemical Analysis
Physical Analysis
Microscopic Study
Microscopic examination is used for the evaluation of many crude drugs. This technique is used to evaluate crude drugs under a microscope.In this technique the drug is first converted into powder form or small pieces or slices to check specific arrangements due to magnification.
Biological Evaluation
When a drug is identified we may convert it into powder form and we have to determine its pharmacological effect.
For this purpose usually, crude drugs are applied to living organisms like bacteria etc. The results are compared with standard drugs and this process is known as biological evaluation.
Chemical Evaluation
In chemical methods of evaluation different chemical techniques are used to evaluate drug activity. For chemical evaluation, different tests and instruments are used to evaluate the active components of the drug.
Physical Factors
Physical factors like moisture contents, density, viscosity, solubility, melting point and boiling etc have also an impact on drug activity and are studied to evaluate the drug.
Moisture content in crude drugs may result in contamination so moisture content is checked by dying the sample at 150 °C.
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