Lecture_1_&_2-_Introduction_to_Basic_Pharmacology.pdf

Introduction to Basic Pharmacology Basic Pharmacology Block PHRM 211, 212, 213, 214 & 215 1 Objectives 1. Define Pharmacology and its main branches. 2. Explain how pharmacology has evolved as a scientific discipline. 3. Describe the present day structure of Pharmacology and its links to other biomed...

Introduction to Basic Pharmacology Basic Pharmacology Block PHRM 211, 212, 213, 214 & 215 1 Objectives 1. Define Pharmacology and its main branches. 2. Explain how pharmacology has evolved as a scientific discipline. 3. Describe the present day structure of Pharmacology and its links to other biomedical Sciences. 4. Identify the properties of an ideal drug. 5. Recognize the FDA Pregnancy Risk Categories of drugs. 2 Definitions of Pharmacology Pharmcology from Greek, (pharmakon, "drug") is the science or study of drug, their preparation and properties, uses and effects. More specifically, it is the study of the interactions that occur between a living organism and exogenous chemicals that alter normal biochemical function. 3 Four Basic Terms 1. Drug: any chemical that can affect living processes 2. Pharmacology: the study of drugs and their interactions with living systems Physical and chemical properties Biochemical and physiological effects Knowledge of the history, source, and use of drugs Absorption, distribution, metabolism and (Pharmacokinetic) Pharmacodynamics. excretion 3. Clinical Pharmacology: study of drugs in humans 4. Therapeutics: use of drugs to diagnose, prevent and treat illness 4 5 More Definitions Biotechnology: production of drugs and other useful products by biological means (recombinant DNA technology). Pharmacogenetics: study of genetic influences on response to drugs. Pharmacogenomics: the use of genetic information to guide the choice of drug therapy on an individual basis (based on the genetic make-up). Pharmacoepidemiology: the study of drug effects at the population level (who decide whether or not a new drug can be licensed for therapeutic use). Pharmacoeconomics: to quantify in economic terms the cost and benefits of drugs used therapeutically. This is important for government authorities and health care systems. 6 Pharmacology: Study of Drugs A drug can be identified by different designations: 1. The chemical name 2. The generic name – This is a non-proprietary name. 3. A trade or brand name – Each manufacture invented a proprietary name for its “own” preparation. 7 Example Chemically, this compound is called 7-chloro1,3-dihydro-1-methyl-5-phenyl-2H-1,4benzodiazepin-2-one. A simpler name is diazepam. – This is a generic name. Preparations containing diazepam were first marketed under the trade name Valium® by its manufacturer, Roche, Inc. 8 Drug leaflet Brand name Indications: a list of medical conditions or diseases for which the drug is meant to be used. Mechanism of action: a description of cellular changes that occur as a result of the drug. Dosage/route – Dosages are mainly the usual adult dose ( 16 - 60 years). – Wherever possible: initial dose, maintenance and maximum doses, duration of drug administration, details for parenteral administration. – Wherever available, doses for children and the elderly are included. – Adjustment of dosage: related primarily to kidney and liver disease. 9 Drug leaflet Warnings/precautions: (e.g. Pregnancy and Lactation). Side effects and adverse reactions: a list of possible unpleasant or dangerous secondary effects. Interactions: a list of other drugs and foods that may alter the effect of a drug and should be avoided during the course of therapy. 10 The Therapeutic objective When you use or handle a drug, remember that: – All substances are poisons (toxic). – The right dose differentiates a poison and a remedy. The objective of drug therapy is to provide the maximum benefit with minimum harm. Five Rights of Drug Administration to give the right drug to the right patient in the right dose by the right route at the right time 11 Properties of Ideal Drug (no drug is ideal!) The most important characteristics of a drug are: Effectiveness: An effective drug is one that produces the responses for which it has been administered. Safety: A safe drug is defined as one that cannot produce harmful effects. – There is no such thing as safe drug. Specificity: A specific drug must act selectively on particular cells and tissues. 12 Additional Properties of Ideal Drug 1. Reversible action – Effects be reversible, example: General Anesthetic 2. Predictability – Know how patient will respond 3. Ease of administration – Number of doses should be low and easy to administer 1. Increase compliance 2. Decrease errors 13 Additional Properties of Ideal Drug 4. Freedom from drug interactions – Should not augment or decrease action of other drugs or have adverse combined effects – Antibacterial effects of Tetracycline can be greatly reduced by taking iron or calcium supplements 5. Low Cost – Easy to afford (especially with chronic illness) – Lifelong medication: hypertension, arthritis, diabetes 14 Pregnancy Categories Group A: controlled studies in pregnancy have failed to demonstrate a risk of the fetus Group B: animal studies show no risk; but no controlled human studies have been performed, or animal studies have shown an adverse effect that has not been confirmed in human. Group C: animal studies have revealed adverse effects and there are no controlled studies in women or studies in women and animals are not available. Benefit must exceed risk. Group D: there is evidence of fetal adverse effects but the benefit may outweigh the risks. Group X: there is strong evidence of fetal abnormalities in human, risk outweighs the benefits. 15 Key Points The most important properties of an ideal drug are: effectiveness, safety, and selectivity. If the drug is not effective, it should not be used. There is no such drug as safe drug: all drugs can cause harm. There is no such thing as selective drug: all drugs can cause side effects. The objective of drug therapy is to provide maximum benefit within minimum harm. Because all patients are unique, drug therapy must be personalised to each individual. 16