SOURCES OF DRUG

TERMINOLOGY

  • Pharmacotherapeutics: it deals with the relative effects of drugs in human systems for various disorders
  • Pharmacokinetics: it is the study of genetically induced drug responses that are often responsible for some idiosyncratic (unexplainable) responses
  • Pharmacodynamics: it deals with experimental science pertaining to theories of drug action
  • Pharmacokinetics: it is the study of how drugs enter the body, reach their site of action, are metabolized and eliminated from the body
  • Absorption: it is the passage of drug molecules into the blood. To exert therapeutic effect the drugs must depend on the physical properties of the drug, route of administration, presence or absence of food in the stomach and interaction with the drugs
  • Distribution: after a drug is absorbed, it is distributed within the body, to tissues and organs and ultimately to its specific site of action
  • Metabolism: after a drug reaches its site of action, it is metabolized into an inactive form, detoxified and degraded chiefly by liver. Also the lungs, kidneys, blood and intestines metabolize drugs
  • Excretion/Elimination: when drugs are metabolized they exit the body through the kidneys, liver, bowels and exocrine glands
  • Drug: it is a substance used in the diagnosis, treatment, cure, relief or prevention of a disease. The terms “medication”, medicine, medicinal are used synonymously with the term “drug”. A drug cannot repair diseased tissues or organs. It can only facilitate normal cellular function. Drugs are given to produce a “therapeutic effect” but these may also cause secondary effects and lethal effects. A single medication may have many therapeutic effects. For example, aspirin is an analgesic, antipyretic and anti-inflammatory drug. It reduces platelet count
  • Side-effects: unintended but anticipated secondary effects, which may be harmless or injurious
  • Adverse reaction: it is the secondary effect which reflects the drug’s action on other areas of the body
  • Toxic effects: usually develop after a prolonged intake of high doses of medication due to accumulation of drug in the blood because of impaired metabolism or excretion
  • Lethal effects: excess amount of drugs within the body may have a lethal effect
  • Iatrogenic disease: disease caused unintentionally by drug therapy. Hepatic toxicity resulting in biliary obstruction
  • Idiosyncratic reaction: when the client over-reacts or under-reacts to a drug or has a reaction different from normal
  • Allergic reaction: it is an unpredictable immunological response after exposure to an initial dose of medication. A drug allergy may be mild or severe (anaphylactic reaction). Common allergy symptoms are utricaria, eczema, pruritus and rhinitis
  • Drug abuse: it is inappropriate intake of a substance either continually or periodically. It has two main facets: drug dependence and drug habituation
  • Drug dependence: it is an individual’s physiological or psychological reliance on or need to take a drug or substance
  • Drug habituation: it denotes a mild form of psychological dependence. The habituated individual develops the habit of taking the substance and feels better after taking it
  • Drug tolerance: an increase in dosage may be needed to cause a therapeutic effect in persons with low metabolism in response to a drug
  • Drug interaction: when one drug modifies the action of another drug interaction occurs
  • Synergistic effect: when the physiological action of two drugs in combination is greater than the effect of the drugs when given separately. For example, diuretics and vasodilators act together to keep the blood pressure at a desirable level
  • Antagonist: drugs that have no special pharmacological action of their own but inhibit or prevent the action of a drug to produce a response
  • Bioavailability: the proportion of the administered dose of a drug, which reaches the circulation
  • Pharmacological/Chemical name: it provides an exact description of the drug’s composition. An example of its chemical name is acetylsalicylic acid (ASA), which is commonly known as aspirin
  • Trade name/Brand name: the name under which a manufacturer markets a drug. A drug may have many different trade names
  • Generic name: the name that is proposed by the company that first develops the drug
  • Material Media: it is a record/book which deal with source, physical and chemical properties, preparations and uses of drugs
  • Pharmacopeias: it is an official document containing a list of drugs which have established their use. It contains a description of physical properties and tests for identification, purification and potency of drugs
  • Monthly Index of Medical Specialties (MIMS): it is published every month. It contains information on drugs, their trade names, along with the name of the manufacturing company with indications and contraindications of the drug, cost of the product
  • Formulary: it is a collection of formulas and prescriptions

DEFINITIONS

  • Drug (Drogue means a dry herb in French) is a substance used in the diagnosis, prevention or treatment of a disease. WHO definition “A drug is any substance or product that is used or intended to be used to modify or explore physiological systems or pathological states for the benefit of the recipient”
  • Pharmacokinetics is the study of the absorption, distribution, metabolism and excretion of drugs, i.e. what the body does to the drug (in Greek Kinesis = movement)
  • Pharmacodynamics is the study of the effects of the drugs on the body and their mechanism of action, i.e. what the drug does to the body. Therapeutics deals with the use of drugs in the prevention and treatment of disease
  • Toxicology deals with the adverse effects of drugs and also the study of poisons, i.e. detection, prevention and treatment of poisonings. (toxicon = poison in Greek)
  • Chemotherapy is the use of chemicals for the treatments of infections. The term now also includes the use of chemical compounds to treat malignancies

Pharmacy is the science of identification, compounding and dispensing of drugs. It also includes collection, isolation, purification, synthesis and standardization of medicinal substances

SOURCES OF DRUGS

The source of drugs could be natural or synthetic

  • Natural sources: drugs can be obtained from

         Plants, e.g. atropine, morphine, quinine, digoxin, pilocarpine, physostigmine

Animals, e.g. insulin, heparin, gonadotropin and antitoxic sera

Minerals, e.g. magnesium sulfate, aluminium hydroxide, iron, sulfur, and radioactive isotopes

Microorganisms: antibacterial agents are obtained from some bacteria and fungi. We thus have penicillin’s, cephalosporins, tetracyclines and other antibiotics

Human: some drugs are obtained from man, e.g. immunoglobulin from blood, growth hormone from anterior pituitary and chorionic gonadotropins from the urine of pregnant women

  • Synthetic, most drugs are now synthesized, e.g. quinolones, omeprazole, sulfonamides, pancuronium, neostigmine
  • Many drugs are obtained by cell cultures, e.g. urokinase from cultured human kidney cells. Some are now produced by recombinant DNA technology, e.g. human insulin, tissue plasminogen activator and some drugs by hybridoma technique, e.g. monoclonal antibodies

DRUG INFORMATION SOURCES

Official Compendia

Official compendia include information sources (or books) on drugs which are recognized by the government of that country as ‘legal standard’. Thus Indian Pharmacopoeia, National Formulary, British Pharmacopoeia, Codex, Pharmaceutical Codex, United States Pharmacopoeia and such other Pharmacopeias are official compendia

  • Pharmacopeia: it is the official publication containing a list of drugs and medical preparations. In Greek ‘Pharmacon’ means drug and ‘poeia’ is to make. It contains list of drugs and related substances that are proved for use, their source, formulae and other information needed to prepare the drugs, their physical properties, tests for their identity, purity and potency
  • Each country may follow its own pharmacopoeia. We thus have Indian pharmacopoeia, British Pharmacopoeia, United States Pharmacopoeia, USSR and Japan Pharmacopeia. The European Pharmacopoeia was published by the Public Health Committee and the European Pharmacopoeia Commission. The international Pharmacopoeia is published by WHO in many languages like English, French, Spanish, and Russian
  • The first pharmacopoeia of India was published in 1868. But later under the British rule, the British Pharmacopoeia was followed. After independence, a committee was set up and Indian Pharmacopoeia was released in 1955. Experts from pharmaceutical industry, drug control laboratories and research and teaching institutions helped the committee. All pharmacopoeia are revised at regular periods to delete old useful drugs and to include newly introduced ones
  • Drug formulary also provides information on drugs. The National formulary is a smaller book that contains information on formulations which are used therapeutically. It is prepared by the National Formulary Committee set up by the Ministry of Health Government of India. Expert opinion is also taken from medical associations, hospitals, teaching institutions and pharmaceutical industry in preparing this book

Non-official Compendia

The books other than the official compendia which provide information on drugs are known as non-official drug compendia

Textbook: these include the textbooks of pharmacology, journals and periodicals. Textbooks like-The Pharmacological basis of therapeutics by Goodman and Gilman, Merck Index, the United States Dispensary, Remington’s Pharmaceutical Sciences and others are quite informative. Many Indian textbooks are also available.

Journals: several journals are published by local, national, international medical organizations. They provide updated information on drugs with research and review articles

Local: several regional (e.g. southern, northern) and state level medical societies release journals at regular intervals

National: Indian Pharmacological Society, Indian Society of Clinical Pharmacology and other similar national level organizations bring out journals at regular intervals

SOURCES OF DRUG - Definition, Terminology, Information
SOURCES OF DRUG – Definition, Terminology, Information

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