CLASSIFICATION OF CRUDE DRUGS | B. PHARM SECOND YEAR SEM IV NOTES | CLASSIFICATION OF DRUGS |

 

CLASSIFICATION OF CRUDE DRUGS

PHARMACOGNOSY & PHYTOCHEMISTRY - I

S.Y B. PHARM (SEM - IV)

classification of drugs in pharmacognosy

The most important natural sources of drugs are higher plant, microbes and animals and marine organisms. Some useful products are obtained from minerals that are both organic and inorganic in nature. In order to pursue (or to follow) the study of the individual drugs, one must adopt some particular sequence of arrangement, and this is referred to a system of classification of drugs. A method of classification should be:

a) Simple,

b) Easy to use, and

c) Free from confusion and ambiguities.

Because of their wide distribution the arrangement of classification in a definite sequence is necessary to understand easily. Although each system of classification has its own merits and demerits, but for the purpose of study the drugs are classified in the following different ways.

  §  Alphabetical classification

  §  Morphological classification

  §  Taxonomical classification

  §  Pharmacological classification

  §  Chemical classification

  §  Chemo-taxonomical classification

  §  Serotaxonomical classification 

ALPHABETICAL CLASSIFICATION:  Alphabetical classification is the simplest way of classification of any disconnected items. The crude drugs are arranged according to the alphabetical order/form of their Latin and English names.

Some of the Pharmacopoeias and reference books which classify crude drugs according to this system are as follows.

1. Indian Pharmacopoeia. (IP) 1955 (Latin), (IP) 1966 (English)

2. British Pharmacopoeia. (BP) (English), (BPC) (English)

3. United States Pharmacopoeia & National Formulary, (USP) (English)

4. British Herbal Pharmacopoeia.

5. British Pharmaceutical Codex.

6. European Pharmacopoeia (Latin Titles).

7. Encyclopedia of common Natural ingredients used in Drugs and cosmetics.

E.g.: Acacia, Benzoin, Cinchona, Dill, Ergot, Fennel, Gentian, Hyoscyamus, Ipecacuanha, Jalap, Kurchi, Liquorice, Myrrh, Nux-vomica, Opium, Podophyllum, Quassia, Rauwolfia, Senna, Uncaria gambier, Vasaka, Wool fat, Yellow bees wax, Zedoary.

ADVANTAGES:

     ·        It is simple method.

     ·        There is no repetition of entries and is devoid of confusion.

     ·        In this system location, tracing and addition of the drug is easy

     ·        No technical person is required for handling the system.

DISADVANTAGES:

     ·        Scientific nature of the drug cannot be identified by this method whether they are organised or unorganised drug.

     ·        This system does not help in distinguishing the drugs of plant, animal and mineral source. (Original source is not clear)

     ·        There is no relationship between previous and successive drug entries.

MORPHOLOGICAL CLASSIFICATION:  In this system, the crude drugs are arranged (Grouped) according to the part of the plant or animal represented into organised (Cellular) drugs and unorganised ( Acellular ) drugs.

Organised (Cellular): The drugs obtained from the direct parts of the plants and containing cellular tissues are called as organized drugs e. g. leaves, barks wood, root, rhizome, seed, fruit, flower, stem, hair and fibers.

Unorganised ( Acellular): The drugs which are prepared from plants by some intermediate physical processes such as incision, drying or extraction with a solvent and not containing any cellular plant tissues are called as unorganized drugs. e.g. dried latex, dried juice, dried extracts, gums, resins, fixed oils and fats, waxes, volatile oil, animal products, minerals (Solids, liquids, semi solids etc).

Difference between organized and unorganized drugs

ORGANIZED DRUGS	UNORGANIZED DRUGS
Cellular structure is present	Cellular structure is absent
Organized drugs are parts of plant & animal like leaf, fruits, seed etc.	Unorganized drugs are obtained from plant & animal by extraction, distillation, incision, expression etc.
Generally identified by morphological character.	Generally identified by organoleptic properties & chemical tests.
They are solid in nature.	They are solid, semi-solid & liquid.
Examples: Digitalis leaf, cinchona bark and ephedra stem	Examples: Agar, gelatin, honey, catechu

EXAMPLES OF ORGANIZED DRUGS:

PLANTS PARTS	DRUGS
Leaves	Tulsi, Datura, Senna, Vasaka, Digitalis
Barks	Arjuna, Cinnamon, Cinchona, Kurchi, Wood Ashoka,
Roots	Rauwolfia, Liquorice, Ipecac
Rhizomes	Ginger, Podophyllum, Turmeric
Flowers	Clove, Saffron, Pyrethrum
Seeds	Black Mustard, Cardamom, Nux vomica, Isapgol
Fruits	Fennel, Coriander, Dill, Amla, Anise, Bael,
Stems	Ephedra
Hair and Fibres	Cotton, Hemp, Jute

 

EXAMPLES OF UNORGANIZED DRUGS:

PLANTS,  ANIMAL, MINERAL	DRUGS
Dried latex	Opium, Papain
Dried Juice	Aloe Vera
Dried extracts	Agar, Catechu, Pectin
Gums	Acacia, Tragacanth, Stericulia
Resins	Benzoin, Colophony, Asafoetida
Fixed oils and fats	Castor , Chaulmoogra, Cotton seed
Waxes	Beeswax, Spermaceti
Volatile oils	Coriander, Cinnamon, Clove
Animal products	Bees wax, Shark liver oil, Gelatin
Minerals	Bentonite, Kaolin, Talc

ADVANTAGES:

     ·        This system of classification is more convenient for practical study especially when the chemical nature of the drug is not clearly understood.

     ·        Morphological classification is more helpful to identify and detect adulteration.

DISADVANTAGES:

     ·        The main drawback of morphological classification is that there is no co-relation of chemical constituents with the therapeutic actions.

     ·        It does not give an idea about biological source, chemical constituents and uses.

     ·        Repetition of drugs or plants occurs.

TAXONOMICAL CLASSIFICATION:  In this system the drug are arranged according to taxonomical studies. The drugs are arranged according to their phylum, order, family, genus and species. It is purely a type of botanical classification or biological classification and restricted mainly to crude drugs from plant source.

CLASS	Angiospermae (Angiosperms)	Plants which produce flowers
	Gymnospermae (Gymnosperms)	Plants which don't produce flowers
SUBCLASS	Dicotyledonae (Dicotyledons, Dicots)	Plants with two seed leaves
	Monocotyledonae (Monocotyledons, Monocots)	Plants with one seed leaf
SUPERORDER	A group of related Plant Families, classified in the order in which they are thought to have developed their differences from a common ancestor.There are six Superorders in the Dicotyledonae (Magnoliidae, Hamamelidae, Caryophyllidae, Dilleniidae, Rosidae, Asteridae), and four Superorders in the Monocotyledonae (Alismatidae, Commelinidae, Arecidae, Liliidae)The names of the Superorders end in –idea
ORDER	Each Superorder is further divided into several Orders.The names of the Orders end in –ales
FAMILY	Each Order is divided into Families. These are plants with many botanical features in common, and is the highest classification normally used. At this level, the similarity between plants is often easily recognisable by the layman. .The names of the Families end in -aceae
SUBFAMILY	The Family may be further divided into a number of sub-families, which group together plants within the Family that have some significant botanical differences.The names of the Subfamilies end in -oideae

 

Example Linnaeus (1707-1778), Swedish biologist

Division - Angiospermae
Class - Dicotyledoneae

Subclass - Sympetalae

Order - Tubiflorae

Suborder - Verbenineae

Family - Labiatae (Lamiaceae)

Subfamily - StachydoideaeTribe Satureieae

Genus - MenthaSpecies Mentha piperita Linnaeus (peppermint)

Varieties - Mentha piperita var. officinalis Sole (White Peppermint); Mentha piperita var. vulgaris Sole (Black Peppermint)

ADVANTAGES:

     ·        Easy for the classification of crude drugs.

 DISADVANTAGES:

     ·        The system is criticized for its failure to recognize the organised / unorganised nature of crude drugs in their morphological studies.

     ·        The system fails to face into an account chemical nature of active constituent and therapeutic significance of crude drugs.

     ·        The drugs obtained from plants having alternate leaves, flowers, seeds, capsules (Hyocyamus, Datura, Bellodonna, Stromonium) are considered with other members of solanaceae.

PHARMACOLOGICAL CLASSIFICATION: This system of classification involves the grouping of crude drugs according to the pharmacological action of their active constituents or their therapeutic uses, regardless of their morphology, taxonomical status, or chemical relationships. • The drugs differing in mechanism of action but having same pharmacological effects are also grouped together, e.g. bulk purgatives, irritant purgatives and emollient purgatives

DRUGS ACTING ON GASTRO-INTESTINAL TRACT

Bitters - Gentian, Quassia, Cinchona

Carminatives - Dill, Mentha, Cardamom

Emetics - Ipecacuanha

Anti-amoebics - Kurchi, Ipecauanha

Bulk laxatives - Agar, Isapghula, Banana

Purgatives - Senna, Castor oil

Peptic ulcer - Derivatives of Glycyrrhitinic acid

DRUGS ACTING ON RESPIRATORY SYSTEM

Expectorant - Liqourice, Ipecacuanha, Vasaka

Antiexpectorant - Stramonium leaves (Atropine)

Antitussives - Opium (Codeine, Noscapine)

Brochodilators - Ephedra, Tea (Theophylline)

DRUGS ACTING ON CARDIO-VASCULAR SYSTEMS

Cardiotonics - Digitalis, Squill, Strophanthus

Cardiac depressants - Cinchona (quinidine), Veratrum

Vaso-constrictors - Ergot (ergotamine), Ephedra

Antihypertensives - Rauwolfia

DRUGS ACTING ON AUTONOMIC NERVOUS SYSTEMS

Adrenergics - Ephedra

Cholinergics - Physostima, Pilocarpus

Anticholinergics - Belladona, Datura

DRUGS ACTING ON CNS

Central analgesics - Opium (morphine)

CNS Stimulants - Coffee ( caffeine)

Analeptics - Nux-vomica, Lobelia, Camphor

CNS depressants - Hyoscyamus, Belladonna, opium,

Hellucinogenics - Cannabis, Poppy Latex

ANTISPASMODICS

Smooth Muscle Relaxants - Opium, Datura, Hyoscyamus

Skeletal Muscle Relaxants - Curare

ANTICANCER: Vinca, Podophyllum, Taxus, Camptotheca

ANTIRHEUMATICS: Aconite, Colchicum, Guggul

ASTRINGENTS: Myrobalan, Black Catechu

ADVANTAGES:

     ·        The special advantage is that if even chemical constituents of the crude drugs are not known they can be classified properly on the basis of therapeutic or pharmacological uses.

DISADVANTAGES:

     ·        Regardless of morphology, taxonomical status or chemical nature, the drugs are grouped together, provided they exhibit similar pharmacological uses.

 Eg: Senna, Castor oil, Jalap, Colocynth are grouped together as purgatives/laxatives because of their common pharmacological action.

CHEMICAL CLASSIFICATION:  Here, the crude drugs are divided into different groups according to the chemical nature of their most important constituent present in the drug to which the pharmacological/therapeutic activity of drug is attributed.

CHEMICAL CONSTITUENTS	DRUGS
Alkaloids	Datura, Vasaka, Vinca, Lobelia
Glycosides	Cascara, Senna, Digitalis
Tannins	Catechu, Myrobalan, Ashoka
Volatile oil	Clove, Eucalyptus, Cinnamon
Lipids	Castor oil, Beeswax, Arachis oil
Carbohydrates and derived products	Acacia, Agar, Honey, Linseed Tragacanth, Starch
Resins	Colophony, Benjoin
Vitamins & hormones	Yeast, Shark liver oil, Insulin
Proteins & enzymes	Gelatin, Papain,

 

ADVANTAGES:

     ·        Chemical constituents are known.

     ·        Medicinal uses are known

DISADVANTAGES:

     ·        Drugs of different origin are grouped under similar chemical titles.

     ·        This type of classification makes no proper placement of drugs containing two different types of chemicals.

Eg: Certain drugs are found to contain alkaloids and glycosides (Cinchona), Fixed oil and volatile oil (Nutmeg) of equal importance together and hence it is difficult to categorize them properly

 

CHEMO-TAXONOMICAL CLASSIFICATION:

This system of classification relies on the chemical similarity of a taxon i.e. it is based on the existence of relationship between constituents in various plants. There are certain types of chemical constituents that characterize certain classes of plants.

The character most often studied in chemotaxonomy are secondary metabolites of pharmaceutical significance such as alkaloids, glycosides, flavonoids, etc.

It is the latest system of classification and gives more scope for understanding the relationship between chemical constituents, their biosynthesis and their possible action

E.g. Tropane alkaloids generally occur in most of the members of Solanaceae

E.g. Volatile oils occur in the members of Umbelliferae and Rutaceae.

E.g. The berberine alkaloid in Berberis and Argemone; Rutin in Rutaceae members, ranunculaceous alkaloids among its members etc.

SEROTAXONOMICAL CLASSIFICATION: Serology is defined as that portion of biology, which is concerned with the nature and interactions of antigenic material and antibodies. Smith (1976) defined it as “the study of the origins and properties of antisera.” When foreign cells or particles (antigens) are introduced into an organism, antibodies are produced in the blood (antiserum). The substance capable of stimulating the formation of an antibody is called antigen and the highly specific protein molecule produced by plasma cells in the immune system in response to the antigen is called antibody.

Serotaxonomy The classification of very similar plants by means of differences in the proteins they contain. The technique is based on the highly specific relationship between antigens and the antibodies produced in response to them. Protein extracted from a plant is injected into the blood of an animal, where it behaves as an antigen. After an interval for the production of antibodies, a blood sample is taken. This can be used to compare the first plant protein (antigen) with extracts taken from other plants.

The study of antigen-antibody reaction is called serology. The substance capable of stimulating the formation of an antibody is antigen. A specific protein molecule produced by plasma cell in the immune system is antibody. The antibodies combine chemically with specific antigen and this combination elevates an immune response. The application of serology in solving taxonomic problems is called serotaxonomy.

THE END