General Pharmacology Basics

Drugs—these are 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.

Prevention—BCG vaccine, Anti-malarial drugs for malarial prophylaxis.

Diagnosis—Barium meal for Peptic ulcer diagnosis.

Treatment—Anti-biotic, Anti-TB drugs.

Medicine—these are chemical substances or mixtures of one or more substances used in suitable convenient form for treatment of diseases.

All medicines are drugs but all drugs are not medicine. Drugs in aseptic formulation are medicines.

Source of drugs—

Natural source	Synthetic source
Plant Animal Microbial Mineral	Semisynthetic Synthetic

Natural source—

Plant source—

Alkaloids—these are nitrogenous organic compounds, derived from plants, insoluble in water. They do not break down when treated with mineral acids. They are named by adding “ine” to their names.

Opium alkaloids—Morphine

Belladonna alkaloids—Atropine

Cinchona alkaloids—Quinine

Glycosides—these are non-nitrogenous organic substances, when treated with mineral acids breaks down into sugar and non-sugar part. The sugar part is responsible for kinetics and the non-sugar part is responsible for the dynamics of the drug. Sugar and no-sugar parts are bound together by glycosidic bond. Ex—cardiac glycosides. Source is oil, gum, starch and other plant sources.

Animal source—

Drugs derived from the living animal cells. Ex—Insulin from the animal pancreas.

Mineral source—

Iron in iron-deficiency anemia, Iodine in goiter.

Microbial source—

From bacteria—Bacitracin.

From fungus—Penicillin, Cephalosporin.

Synthetic source—

Most drugs which are more common and effective are synthetic—Paracetamol, Aspirin.

Semisynthetic source—

Ampicillin, Pethidine etc.

Naming of drugs—non-proprietary (generic) and proprietary (trade) name. Ex—Amoxicillin is the generic name and Pentamox is the trade name, also paracetamol—Napa, Ace etc.

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