What is Adulteration?
Adulteration is defined as the admixture of a genuine article with spurious or harmful substances, resulting in a poorer quality product. It is one of the most serious concerns in the quality control of crude drugs.
Common examples:
- Papaya seeds mixed with black pepper
- Brick powder mixed into red chilli powder
Methods of Drug Adulteration
Adulteration may be accidental or deliberate. It is especially common with drugs that are sold illegally or imported from other countries. The main methods include:
A. Substitution with Manufactured Materials Artificially manufactured materials that resemble genuine drugs in form and appearance are used as substitutes. Example: Paraffin wax coloured yellow to substitute beeswax.
B. Substitution with Inferior Material Drugs are replaced with substandard commercial material of the same type. Example: Cloves adulterated with mother cloves; Saffron adulterated with dried flowers of Carthamus tinctorius (Safflower).
C. Substitution with Exhausted Material Exhausted materials are vegetable residues left after the active components have already been extracted for drug preparation. Example: Alexandrian Senna substituted with Arabian Senna; exhausted Clove and Ginger used as adulterants.
D. Substitution with Cheap Natural Substances Cheaper natural substances with no relation to the genuine article are used. Example: Japan wax substituted for beeswax; Sterculia gum substituted for Tragacanth.
E. Adulteration with Non-Plant Material Plant materials are sometimes mixed with worthless non-plant substances to increase bulk or weight.
F. Excessive Adventitious Matter Inclusion of unwanted foreign matter beyond acceptable limits.
Evaluation of Crude Drugs
Evaluation of crude drugs means identifying their quality and purity, and detecting the nature and extent of any adulteration present. Depending on the form of the drug — whole, powdered, or liquid — different techniques are applied.
Crude drugs are identified on the basis of their morphological, histological, and chemical characteristics. The standardization techniques used are:
1. Physical Evaluation
Physical standards are determined wherever possible. Parameters include:
- Specific gravity and density
- Optical rotation
- Refractive index
- Melting point
- Viscosity
- Solubility in different solvents
These physical constants help detect adulteration, especially in liquid drugs.
2. Chemical Evaluation
Chemical evaluation involves different chemical tests and assays to identify and quantify the active constituents of crude drugs. Methods include:
- Isolation, purification, and identification of active constituents
- Quantitative tests such as Acid value and Saponification value
Chemical evaluation helps in proper identification of various crude drugs and confirms their composition.
3. Biological Evaluation (Bioassay)
The potency of certain crude drugs cannot be measured by physical or chemical methods alone — it must be assessed by its effect on a living organism. This is called bioassay.
Bioassay measures whether a test sample can produce the same biological effect as a standard preparation. It may be tested on bacteria, fungi, animal tissue, or whole animals.
4. Morphological Evaluation (Organoleptic)
This method evaluates drugs using the five senses — colour, odour, taste, size, shape, texture, touch, and sound. The study of the form of a crude drug is called morphology, while its written description is called morphography.
Morphological evaluation is useful in identifying adulteration in:
- Seeds of Strychnos nux-vomica vs Strychnos nux-blanda or Strychnos potatorum
- Caraway vs Indian dill
- Alexandrian Senna vs Dog Senna
5. Microscopic Evaluation
Microscopic evaluation allows detailed examination of a drug’s histological (tissue-level) structure. It is particularly useful for:
- Identifying organised drugs by their known histological characters
- Studying powdered drugs using micro-chemistry (applying chemical tests to small quantities under the microscope)
- Examining very thin histological sections of the drug
The microscope magnifies minute structural details that cannot be seen with the naked eye, making it possible to confirm the identity and purity of plant-origin drugs.
D.Pharma 1st Year — All Subjects Notes
D.Pharma 2nd Year — All Subjects Notes