DRUG: Definition, Nomenclature, Classification, Sources Definition of a Drug: The term "drug" means (A) articles recognized in the official United States Pharmacopoeia, official Homoeopathic Pharmacopoeia of the United States, or official National Formulary, or any supplement of them; and (B) articles intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease in man or other animals; and (C) articles (other than food) intended to affect the structure or any function of the body of man or other animals; and (D) articles intended for use as a component of any article specified in clause (A), (B), or (C). [FD&C Act, sec. 201(g)(1)]. http://www.fda.gov/opacom/laws/fdcact/fdcact1.htm Definition of a Drug: • Diagnosis – used to identify a disease. Example – barium sulfate in x-ray of GIT. • Prevention – used to prevent the occurrence of diseases. Example – vaccines against diseases like tuberculosis, whooping cough, typhoid etc. • Cure – to cure or get rid of some disease. Example – antibiotics to cure infections caused by microorganisms. • Control – keep the disease under control although it may not be fully cured. Example – anti-diabetic drugs to control diabetes, antihypertensive drugs to treat hypertension and control the blood pressure. • Mitigate – reduce some of sufferings or relief some symptoms. Example –Painkillers in headache, smooth muscle relaxant in stomachache. Medicine • OTC • Prescription only ©1 Nomenclature of Drugs • Generic name : Shortened name of a drug, usually given by the health authorities and officially used in the pharmacopoeias like BP and USP. Sometimes, there may be more than one generic name of a particular drug. • For example BP name USP name Paracetamol Acetaminophen • Chemical name : Name based on the chemical structure of the drug. The name is applicable only for pure drugs. Nomenclature of Drugs O For example HN C CH3 • Generic name Paracetamol • Chemical name N-acetyl para-aminophenol • or OH • 4-hydroxyacetanilide • or • N-(4- Hydroxyphenyl)acetamide. • Brand name / Trade name : Name of a drug product ( medicine ) given by the manufacturer. For example – Napa Tablet ( Beximco ) for Paracetamol tablet – Ace Tablet ( Square ) for Paracetamol tablet Classification of drugs Drugs can be classified on the basis of various parameters. On the basis of pharmacological action: Analgesic and antipyretic drug – Paracetamol Anti-inflammatory drug – Diclofenac sodium Antihypertensive drugs - propranolol On the basis of target organ: Gastrointestinal drugs (acting on the gastrointestinal tract) – antacids Cardiovascular drugs (acting on the cardiovascular system ) – antihypertensive. CNS Drugs (acting on central nervous system)- Diazepam Classification of drugs On the basis of therapeutic uses : Antidiarrheal – acting against diarrhea Anti-diabetic – acting against diabetes On the basis of target receptors : β-blockers – blocks the β-receptors H2-blockers - blocks the H2-receptors Classification of drugs BNF drugs and preparations • 1 Gastro-intestinal system • 2 Cardiovascular system • 3 Respiratory system • 4 Central nervous system • 5 Infections • 6 Endocrine system • 7 Obstetrics, gynaecology, and urinary-tract disorders • 8 Malignant disease and immunosuppression • 9 Nutrition and blood • 10 Musculoskeletal and joint diseases • 11 Eye • 12 Ear, nose, and oropharynx • 13 Skin • 14 Immunological products and vaccines • 15 Anaesthesia Practical Classifications/ ATC drug classification • The Anatomical Therapeutic Chemical (ATC) classification system by the WHO. • The system provides a global standard for classifying medical substances and serves as a tool for drug utilization research. • The system is divided into 14 general groups according to the body system on which they act. Example of ATC code structure (metformin) Level Code Content Group 1 A Alimentary tract Anatomical main and metabolism group 2 A10 Drugs used in Therapeutic diabetes subgroup 3 A10B Oral blood glucose Pharmacological lowering drugs subgroup 4 A10BA Biguanides Chemical subgroup 5 A10BA02 Metformin Chemical substance Sources of Drug Plant (flowers, trees, bushes) Micro-organisms (bacteria, fungi) A) The Natural Animal life (frogs, snakes, scorpions) Biochemicals (Neurotransmitters, hormones) Marine chemistry (corals, bacteria, fish etc) B) Synthetic Drugs Chemical synthesis C) Semi-Synthetic Drugs Sources of Drug The Natural World Plant drug – opium, belladonna, digitalis Animal drug – Cod liver oil Mineral drug – sodium chloride Natural drug may be used in the crude form or may be used after extraction and purification of the active constituent. Crude drug – digitalis, opium Purified constituent – digoxin, morphine Drug from the Natural World PLANT EXTRACTS MORPHINE POPPY CAPSULE Drug from the Natural World PLANT EXTRACTS • OPIUM - Morphine • CINCHONA BARK - Quinine CINCHONA Drug from the Natural World PLANT EXTRACTS WILLOW TREE - SALICYLIC ACID O OH O OH Acetic OH anhydride O CH3 O Aspirin Drug from the Natural World VENOMS AND TOXINS O C OH O C N CH3 HS Captopril (anti-hypertensive) Drug from the Natural World MeO VENOMS AND TOXINS CH 3 N HO CH 3 O H H O H3 C N OH H3 C OMe Tubocurarine (from curare) Drug from the Natural World ENDOGENOUS COMPOUNDS NATURAL LIGANDS FOR RECEPTORS OH O N H Antagonist H HO N OH Me HO ADRENALINE PROPRANOLOL Me NH2 H N NHMe HN S HN N N HISTAM INE CN Antagonist CIM ETIDINE Drugs obtained by biotechnology • Drugs can also be obtained by biotechnology. • For example previously insulin was obtained from animal sources. Now- a-days insulin is obtained from bacteria with the help of biotechnology. Drugs from the Synthetic World O H2N S NH2 O SULFANILAMIDE Drugs from the Synthetic World ONO2 ONO2 ONO2 Semi-Synthetic Drugs The drug is obtained by partial synthesis starting from a natural constituent. Example – semi-synthetic antibiotics like amoxicillin, heroin from morphine.
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