Classification of Crude Drugs in Pharmacognosy
Introduction:
In Pharmacognosy, crude drugs are obtained from natural sources such as plants, animals, and minerals. To study and understand these drugs systematically, they are classified using different methods. Classification helps pharmacy students and professionals to identify drugs easily, understand their properties, relate them to their sources, and apply them correctly in medicine.
Crude drugs can be classified based on their names, biological origin, external structure, chemical composition, and therapeutic action. The major systems of classification include alphabetical, taxonomical, morphological, pharmacological, chemical, and chemo-taxonomical classification.
1. Alphabetical Classification:
In alphabetical classification, crude drugs are arranged in alphabetical order according to their English, Latin, or scientific names. This method is commonly used in pharmacopoeias, dictionaries, and reference books.
This system is simple and allows quick location of drugs without prior scientific knowledge.
Examples include Acacia, Belladonna, Cinchona, and Digitalis.
2. Taxonomical Classification:
Taxonomical classification arranges crude drugs according to the biological classification of their source organisms. It follows the scientific system of classification based on kingdom, family, genus, and species.
This method helps in understanding the botanical relationships and evolutionary similarities between drug-producing plants.
Examples include Digitalis purpurea from the family Scrophulariaceae, Atropa belladonna from the family Solanaceae, and Cinchona officinalis from the family Rubiaceae.
3. Morphological Classification:
In morphological classification, crude drugs are grouped according to the plant part used or their external appearance. This system is widely used in pharmacognosy laboratories for identification of crude drugs.
Leaves include Senna and Digitalis. Roots and rhizomes include Rauwolfia and Ginger. Barks include Cinchona and Cinnamon. Fruits and seeds include Coriander and Nux vomica. Flowers include Clove and Saffron. Gums and resins include Gum acacia and Asafoetida.
This classification is helpful for practical identification based on size, shape, colour, and surface characteristics.
4. Pharmacological Classification:
Pharmacological classification groups crude drugs based on their therapeutic action or effect on the human body. This method is clinically important as it directly relates drugs to their medicinal use.
Examples include Opium and Clove oil as analgesics, Quinine as an antimalarial, Senna and Castor oil as purgatives, Digitalis as a cardiotonic agent, Liquorice as an expectorant, and Belladonna as an antispasmodic.
This system is useful for doctors and pharmacists in selecting drugs for treatment.
5. Chemical Classification:
Chemical classification groups crude drugs based on their major chemical constituents. This method is important in phytochemistry, drug analysis, and standardization.
Alkaloid-containing drugs include Morphine, Quinine, and Atropine. Glycoside-containing drugs include Digitalis and Senna. Tannin-containing drugs include Catechu and Clove. Terpenoid-containing drugs include Camphor and Menthol. Saponin-containing drugs include Liquorice and Dioscorea. Volatile oil-containing drugs include Cinnamon oil and Eucalyptus oil.
This classification helps in understanding chemical tests, extraction, and mechanisms of action.
6. Chemo-taxonomical Classification:
Chemo-taxonomical classification combines chemical and taxonomical approaches. Drugs are classified based on the chemical constituents produced by specific plant families.
Plants belonging to the Solanaceae family produce tropane alkaloids such as Atropine and Hyoscyamine. Papaveraceae family plants contain isoquinoline alkaloids such as Morphine and Codeine. Rubiaceae family plants produce indole alkaloids such as Quinine.
This method helps in predicting chemical constituents in related species and aids in the discovery of new drugs.
Summary:
Different classification systems of crude drugs serve different purposes in Pharmacognosy. While alphabetical classification is simple and convenient, taxonomical and chemical classifications provide scientific depth. Morphological and pharmacological classifications are practical and clinically useful, whereas chemo-taxonomical classification helps in advanced research and drug discovery.
Frequently Asked Questions (FAQs)
1. Why is classification of crude drugs important?
Classification helps in systematic study, identification, understanding, and proper use of crude drugs in pharmacy.
2. Which classification is most useful for laboratory identification?
Morphological classification is most useful for identifying crude drugs in practical laboratory work.
3. Which classification is important for clinical use?
Pharmacological classification is important because it groups drugs based on their therapeutic action.
4. What is chemo-taxonomical classification?
It is a classification method that combines plant taxonomy with chemical constituents to study relationships between plants and their active compounds.
5. Which classification is commonly used in pharmacopoeias?
Alphabetical classification is commonly used in pharmacopoeias and reference books.
