Quality Control of Crude Drugs
Introduction:
Quality control of crude drugs is an essential part of Pharmacognosy. Crude drugs obtained from natural sources must be pure, safe, and effective to produce the desired therapeutic effect. Due to high demand, limited availability of genuine materials, and commercial pressure, crude drugs are often adulterated either intentionally or unintentionally.
To ensure safety, quality, and medicinal value, different evaluation techniques are used. These methods help in identifying adulteration and confirming the authenticity and purity of crude drugs.
Methods of Adulteration of Crude Drugs:
Adulteration refers to the substitution, mixing, or contamination of a crude drug with inferior, fake, harmful, or worthless substances. Adulteration reduces the quality, purity, and therapeutic value of the drug.
1. Substitution with Inferior Drugs:
- A cheaper or less effective drug is substituted for the genuine crude drug.
- Example: Papaya seeds mixed with black pepper.
2. Substitution with Exhausted Drugs:
- Drugs that have already been used for extraction of active constituents are sold again as fresh crude drugs.
- Example: Exhausted clove or ginger after oil extraction.
3. Addition of Foreign Organic Matter:
- Unwanted plant parts, weeds, stems, sand, or stones are mixed to increase bulk.
- Example: Stems mixed with tea leaves or sand added to crude drugs.
4. Powder Adulteration:
- When crude drugs are in powdered form, they can be easily adulterated with cheaper powders.
- Example: Brick powder mixed with red chili powder.
5. Adulteration with Artificially Manufactured Substances:
- Artificial or synthetic substances are prepared to resemble genuine crude drugs.
- Example: Artificially colored wax used to imitate beeswax.
6. Adulteration by Spoilage or Poor Storage:
- Improper storage leads to spoilage by microorganisms, insects, moisture, or heat.
- Example: Mold growth in dried plant materials.
7. Substitution with Similar-Looking Drugs:
- Inferior drugs with similar shape, color, or odor are substituted for genuine drugs.
- Example: Dyed maize fibers used in place of saffron.
8. Deliberate Coloring or Bleaching:
- Dyes or chemicals are added to improve appearance and make the drug look fresh.
- Example: Turmeric colored with lead chromate.
9. Mixing with Heavy Materials:
- Heavy substances are mixed to increase weight.
- Example: Stones mixed with asafoetida or gums.
Evaluation of Crude Drugs:
Evaluation of crude drugs ensures that the drug is authentic, pure, potent, and of acceptable quality. Pharmacognostical evaluation includes several methods based on sensory, microscopic, physical, chemical, and biological characteristics.
1. Organoleptic Evaluation:
- This evaluation is carried out using sense organs such as sight, smell, taste, and touch.
- Parameters include color, shape, size, odor, taste, and texture.
- Example: Clove has a strong aromatic odor and pungent taste.
2. Microscopic Evaluation:
- Microscopy is used to identify powdered or unorganized crude drugs. It helps detect adulterants and confirm characteristic plant structures such as stomata, trichomes, fibers, vessels, and crystals.
- Example: Stomatal number in senna leaves.
3. Physical Evaluation:
- Physical constants help determine purity and quality of crude drugs.
- These include moisture content, ash values, extractive values, volatile oil content, and melting or boiling points.
4. Chemical Evaluation:
- Chemical tests are performed to detect and confirm the presence of active constituents.
- Examples include ferric chloride test for tannins and Dragendorff’s test for alkaloids.
5. Chromatographic Evaluation:
- Chromatographic techniques separate and identify chemical constituents of crude drugs.
- Methods include Thin Layer Chromatography, High Performance Liquid Chromatography, and Gas Chromatography.
6. Biological Evaluation:
- This method measures the biological activity of crude drugs using animals, tissues, or microorganisms.
- Example: Digitalis tested on frog heart for cardiotonic activity.
7. Pharmacological Evaluation:
- Pharmacological evaluation tests the therapeutic effect of crude drugs on specific organs or systems.
- Example: Antimicrobial testing of garlic extract.
8. DNA Fingerprinting / Molecular Evaluation:
Modern molecular techniques identify plant species at the genetic level and help prevent substitution and adulteration of herbal drugs.
Summary:
Quality control of crude drugs is essential to ensure safety, efficacy, and therapeutic reliability. Understanding methods of adulteration and evaluation techniques helps pharmacists maintain drug quality and protect public health.
Frequently Asked Questions (FAQs)
1. What is adulteration of crude drugs?
Adulteration is the mixing or substitution of crude drugs with inferior, fake, or harmful substances, reducing quality and effectiveness.
2. Why is quality control important in Pharmacognosy?
Quality control ensures that crude drugs are pure, safe, effective, and free from adulterants.
3. Which evaluation method uses sense organs?
Organoleptic evaluation uses sight, smell, taste, and touch.
4. Which evaluation method is useful for powdered drugs?
Microscopic evaluation is especially useful for identifying powdered crude drugs.
5. What is the role of chromatography in crude drug evaluation?
Chromatography helps separate, identify, and standardize chemical constituents and detect adulteration.
