Drugs—chemical substances used or intended to be used to modify or explore the physiological condition or pathological state for the benefit of the recipient. Drugs may be used for prevention, diagnosis and treatment.
Introduction to Pharmacology
Drugs—chemical substances used or intended to be used to modify or explore the physiological condition or pathological state for the benefit of the recipient. Drugs may be used for prevention, diagnosis and treatment.
It is the science of drugs derivedfrom two Greek words: Pharmakon (the Greek word for drugs) and logos (theGreek word for science). It is the study of the effects of chemicals on livingtissues. The word drug refers to a dry substance and probablyreflects the use of herbs in early therapy.
Broadlydefined, a drug is a chemical substance that can alter or influence theresponsiveness of a biological system.
Accordingto the Food and Drug Administration (FDA) all drugs are chemicals, BUT, allchemicals are not drugs. All drugs arepoisons, BUT, all poisons are not drugs.
FDA defines the chemical “a substance composedof a combination of elements (electrons, protons, and neutrons)” and drug “achemical which is utilized for the diagnosis, prevention, cure or ameliorationof an unwanted health condition”
Accordingto Federal Food, Drug, and Cosmetic (FDC) Act, the term “drug” means (A)articles recognized in the official United States Pharmacopeia, officialHomeopathic Pharmacopoeia of the United States,or official National Formulary, or any supplement to any of them; and (B)articles intended for use in the diagnosis, cure, mitigation, treatment orprevention of disease in man or other animals; and (C) articles (other thanfood) intended to affect the structure or any function of the body of man orother animals; and (D) articles intended for use as a component of any articlesspecified in clause (A), (B), and (C), and “Food” means (1) articles used forfood or drink for man or other animals, (2) chewing gum, and (3) articles usedfor components of any other such article.
Major divisions of pharmacology—
1. Pharmacokinetics.
2. Pharmacodynamics.
Other divisions—
1. Pharmacotherapeutics.
2. Clinical pharmacology.
3. Pharmacogenetics
4. Immunopharmacology
5. Pharmacognosy
6. Toxicology
7. Pharmacopoeia
Pharmacokinetics—(what the body does to the drug)—it is the branch of pharmacology that deals with drug dose, routes of administration and absorption, distribution, metabolism and excretion.
Pharmacodynamics—(what the drug does to the body)—it is a branch of pharmacology that deals with the mechanism of action, pharmacological effects, indication and contraindication of use and adverse effects of drugs.
Toxicology—it is the branch of pharmacology which deals with poisonous drugs, their source, properties, sign-symptoms they produce and management of poisoning.
Pharmacopoeia—it is a book published by authority of recognized body which contains list of drug, their properties, description, preparation and method of prescribing.
Pharmacogenetics—it is that branch of pharmacology which deals with genetic variations to the drug response.
Ex—
Isoniazide is an anti-tubercular drug which is metabolized by acetylation. If acetylation process is increased in that person for genetic factor then more drug is needed.
Patients with glucose-6-phosphate dehydrogenase deficiency may produce haemolytic anaemia if anti-malarial drug is given