Drug Evaluation Process

Evaluation of Crude Drugs

• Evaluation of drugs means confirmation and compliance of drug quality and purity.
• The aim of drug evaluation is to identify and determine the quality and purity of the crude drug and detect nature of adulteration.

Importance of Evaluation

• Biochemical variations in the drug may occur.
• Deterioration may happen due to storage.
• Substitution and adulteration may be present due to carelessness, ignorance, etc.

Methods of Evaluation

• Estimation of active constituents present in the crude drug.
• Morphological and microscopic analysis.
• Physical evaluation of crude drug.
• Biological behavior of crude drug extracts.
• Determination of pharmacological action.

Morphological / Organoleptic Evaluation

• Shape and size.
• Color.
• External markings (fractures, etc.).
• Internal color, odor, and taste.
• All organized drugs can be evaluated using this method (barks, underground structures, leaves, flowers, fruits, seeds, herbs).
• Sensory characters: color, texture, odor, and taste.

Physical Evaluation

• Moisture content (determined by heating at 105°C in an oven to constant weight).
• Viscosity of liquid (constant at a given temperature and an index of composition).
• Melting point (one of the parameters to judge purity of crude drugs).
• Solubility (the presence of adulterant in a drug could be indicated by solubility).
• Optical rotation (determined at 25°C using a sodium lamp as the source of light).
• Refractive index (ratio of the velocity of light in vacuum to its velocity in the substance).
• Ash values (ash represents inorganic salts, naturally occurring in a drug or adhering to it as a form of adulteration).
• Extractives (various solvents are used for determination of extractives).

Chemical Evaluation

• It consists of different chemical tests and chemical assays.
• The isolation, purification, and identification of active constituents are chemical methods of evaluation.
• Quantitative chemical tests like acid value, saponification value, sulphated ash, ester value, and acetyl value are useful in evaluation of resins, etc.