Sources of Drugs

Sources of Drugs

Natural Sources

Plants

  • Oldest source of drugs, used empirically.

  • Derived from leaves, seeds, flowers, roots, bark, etc.

  • Problems:

    • Identification of plant species.

    • Influence of climatic and social conditions of the area.

    • Impact of the season of collection.

    • Conditions of storage.

    • Standardization of active principle.

    • Purity of active ingredient.

    • Maintenance of supply line.

    • Active principle is synthesized after detection.

Leaves

  • Digitalis Purpurea: Source of Digitoxin and Digoxin, which are cardiac glycosides.

  • Eucalyptus: Leaves are an important component of cough syrup.

  • Tobacco: Leaves give nicotine.

  • Atropa belladonna: Gives atropine.

Flowers

  • Poppy (Papaver somniferum): Gives morphine (opioid).

  • Vinca rosea: Gives vincristine and vinblastine (anti-neoplastic drugs).

  • Rose: Gives rose water used as a tonic.

Fruits

  • Senna pod: Gives anthracine, which is purgative (used in constipation).

  • Calabar beans: Give physostigmine, which is a cholinomimetic agent.

Seeds

  • Nux Vomica: Gives strychnine, a CNS stimulant.

  • Castor oil seed: Gives castor oil.

Roots

  • Ipecacuanha: Gives Emetine, used to induce vomiting in accidental poisoning; also has amoebicidal properties.

  • Rauwolfia serpentina: Gives reserpine, a hypotensive agent. Reserpine was historically used for hypertension treatment.

Bark

  • Cinchona: Gives quinine and quinidine, which are antimalarial drugs. Quinidine also has antiarrhythmic properties.

  • Atropa belladonna: Gives atropine, which is anticholinergic.

  • Hyoscyamus Niger: Gives Hyoscine, which is an anticholinergic.

Various Forms of Plant Drugs

  • Extract, infusions, decoction, powders, etc.

  • Chemicals (alkaloids, glycosides, oil, resins, tannins, gums etc.) isolated from different forms are used for humans and animals

Animals

  • Modern drugs source.

  • Active principles include proteins, oils and fats, enzymes, and hormones.

  • Examples: gonadotropins, heparin, insulin, thyroid extract, and enzymes.

Microorganisms

  • Antibiotics derived from fungi and bacteria after the discovery of penicillin in 1928 and its use in 1940.

  • Used for infective diseases.

  • Examples: penicillin, streptomycin, tetracycline, chloramphenicol, and erythromycin.

Minerals

  • Metals, metalloids, non-metal substances, and their compounds.

  • Examples: iron, calcium, magnesium, aluminum, sodium, potassium, Sulphur, lithium, etc.

  • Iron: Used in the treatment of iron deficiency anemia.

  • Mercurial salts: Used for syphilis.

  • Zinc: Used as a zinc supplement needed for body’s defensive (immune) system to properly work. Zinc oxide paste is used in wounds and eczema.

  • Iodine: Antiseptic and may be used as a supplement.

  • Gold salts: Used in the treatment of rheumatoid arthritis.

  • Fluorine: Has antiseptic properties.

  • Selenium: Selenium sulphide is used in anti-dandruff shampoo.

Semi-Synthetic

  • The nucleus of the drug is obtained from a natural source, but the chemical structure is altered.

  • Often involves complex molecules.

  • May be more expensive and used for impure natural compounds.

  • Examples: 6-aminopencillanic acid (from fungus), semi-synthetic human insulin (from pork insulin).

Synthetic

  • Drugs are synthesized in a pharmaceutical laboratory.

  • May involve organic, inorganic, or a combination of both compounds.

  • Examples: chloroform, ether, nitrous oxide, chloral hydrate.

  • Includes antipyretics, sulphonamides, antihistamines, anticonvulsants, anti-anxiety drugs, etc.

Recombinant DNA Technology

  • Process of “gene cloning”.

  • Involves cleavage of DNA by enzyme restriction endonucleases.

  • The desired gene is coupled to rapidly replicating DNA (viral, bacterial, or plasmid).

  • The new genetic combination is inserted into bacterial cultures, which allow production of the genetic material.

  • Human insulin, human proinsulin gene to form insulin

  • Growth hormone, tissue plasminogen activator, vaccines, interferon, erythropoietin, interleukins granulocyte-colony stimulating factor.

  • Advantages:

    • Huge amounts of drugs can be produced.

    • Drug can be obtained in pure form.

    • Less antigenic.

  • Disadvantages:

    • Well-equipped laboratory is needed.

    • Highly trained staff is required.

    • Complex and complicated technique.