Intro to Pharmacology PDF

INTRODUCTION TO PHARMACOLOGY ADEOLUWA O.A. DEPARTMENT OF PHARMACOLOGY, COLLEGE OF MEDICINE AND HEALTH SCIENCES, AFE BABALOLA UNIVERSITY  WHAT IS “PHARMACOLOGY”?  Pharmacology is from the Greek word ‘Pharmakon’ (dru...

INTRODUCTION TO PHARMACOLOGY ADEOLUWA O.A. DEPARTMENT OF PHARMACOLOGY, COLLEGE OF MEDICINE AND HEALTH SCIENCES, AFE BABALOLA UNIVERSITY  WHAT IS “PHARMACOLOGY”?  Pharmacology is from the Greek word ‘Pharmakon’ (drug), and ‘logos’ (science). Combining both, pharmacology means science of drugs.  Pharmacology is defined as the study of how chemical agents (drugs, hormones, neurotransmitters, growth factors, and toxic agents in the environment) affect living processes.  It can also be defined as the study of how drugs interact within biological systems to produce a change in function.  In its entirety, pharmacology embraces the knowledge of the origin, physical and chemical properties, mechanism of action, effects and uses of drugs.  WHO IS THE PHARMACOLOGIST?  The medicinal/organic chemists may create the candidate compound (sometimes referred to as a new chemical entity, (NCE), the Pharmacologist is responsible for testing the candidate compound for pharmacological activity. This will ultimately lead to the discovery of novel drugs for therapeutic intervention.  The Pharmacologist Identify drug targets in order to learn how drugs work (actions), and how the drugs are modified within the organism. SCOPE OF PHARMACOLOGY  Centuries ago, most drugs were highly impure mixtures of plants or animal parts.  A physician was required to know only the effect to expect from a preparation.  How the mixture produced such effect was beyond the knowledge of man.  Today the situation has changed drastically, a physician is required to know the expected effect, how it is brought about and how the drug interacts with the body component to initiate such effect.  This broader knowledge of the interaction to produce therapeutic effect is termed pharmacology.  It relies on the knowledge of biochemistry, organic chemistry and physiology.  WHAT IS A DRUG?  A drug is any substance or product this is used or intended to be used to modify or explore physiological system of pathological state for the beneficit of recipient.  They can be used for used for diagnosis, prevention and treatment of diseases.  A drug can also be defined as any chemical or biological substance, synthetic or non-synthetic, that when taken into the organism's body, will in some way alter the functions of that organism.  Drugs are usually distinguished from endogenous biochemical by being introduced from outside the organism. For example, insulin is a hormone that is synthesized in the body; it is called a hormone when it is synthesized by the pancreas inside the body, but if it is introduced into the body from outside, it is called a drug.  DRUG Vs MEDICINE Drug Medicine  Any substance designed  Any substance designed to produce a specific to prevent or treat reaction in the body. diseases.  May have either positive  Effect is always positive, or negative effect. beneficial, and intended for improvement of health  Have potential for condition. addiction and are usually  Does not have potential controlled. for addiction.  E.gs morphine, codeine,  Cough syrup, blood tonic, cocaine etc. etc. Note: all medicines are drugs but not all drugs are medicines SOURCES OF DRUGS  Animals – oil, steroid and hormone- These are products from animals e.g. Thyroxine and insulin  Minerals: Inorganic source e.g. magnesium trisilicate, MgS04, CaC03  Plants- alkaloid, glycocide, tannins, anthraquinone e.g. yohimbine, atropine, vincristine  DRUG NOMENCLATURE There are four categories of names:  Chemical name: This describes the substance chemically e.g. propan-2-ol (propranolol)  This type of name is cumbersome and it is not suitable  Code name: e.g. R015-1788 (Flumazenil, a benzodiazepine antagonist). This name is useful at the early stage of investigation to conceal the identity. It is also used to identify the drug pending when the drug will be given the approved name/ approved.  Generic name/ non-proprietary : This is the name accepted by a competent scientific body e.g. USAN(United State Adopted Name Council). Until the drug is included in a pharmacopeia. The non-proprietary name may also be called the approved name.  Proprietary name/Brand name: This is the name assigned by the manufacturer e.g. ciprotab, spardium, sparflux etc. EFFECTS OF DRUG ACTIONS  Adverse Effects: A drug administered at a given dose has both a desired i.e. therapeutic and undesired i.e. adverse or side effect. They are unwanted but often unavoidable that occur at therapeutic dose.  They can be predictable and increase with dose  Idiosyncrasy- it is a genetically determined abnormal reaction to chemicals. For instance barbiturate that causes sedative hypnotics will cause excitement and mental confusions in such patients.  Overdosage/Toxicity: This could be due to administration of a single large dose or accumulation of repeated doses. It manifests as exaggerated form of the pharmacological action of the drug (Toxicity). E.g overdose of an anticoagulant will results in hemorrhage  Hypersensitivity/ allergy: Mediated by antigen-antibody reaction. It requires previous exposure and sensitization to drug.  Tolerance: They are two types (a) acute tolerance/tachyphylaxis which is short leaved (b) dependent state  This develops more slowly and persists longer. It involves profound cellular disorganization and severe alteration of function occur.  Tolerance is said to occur when doses of a drug many times larger than that which evoke a maximum response originally now produce no detectable effect.  Contraindication: This is a physiological or mental state of a patient in which a particular drug should not be given. E.g. an asthmatic patient should not be given cholinergic agent which causes bronchial constriction that aggravate the situation. COMBINED EFFECT OF DRUGS  When two or more drugs are given simultaneously or in quick succession, they may be either indifferent to each other or synergism or antagonism.  The interaction may take place at pharmacokinetic level or at pharmacodynamics level.  Synergism: this occurs when two drugs coupled together show an augmented effected. In a synergistic pair both the drugs can have action in the same direction or given alone one may be inactive but still enhance the action of the other when given together. Synergism can be:  Additive: the effect of the two drugs are in the same direction and simply add up, i.e. when the combined effect of two drugs given together is not more than the sum of the individual action eg. Chloroform and ether – both are volatile anesthetic agents.  Aspirin + paracetamol – as analgesic/antipyretic  Ephedrine + theophylline – as bronchodilator  Sulfadiazine + sulfamerazine + sulfamethazine – as antibacterial.  Potentiation: the effect of combination is greater than the sum of their individual effects. of the components.  This is always the case when one component is inactive as such. Eg.  Acetylcholine + physostigmine (inhibition of break down)  Levodopa + carbidopa/benserazide (inhibition of peripheral metabolism)  Adrenaline + cocaine/desipramine (inhibition of uptake)  PHARMACOLOGY: SUB-DIVISIONS/BRANCHES  Two main divisions of pharmacology: Pharmacokinetics and pharmacodynamics. Pharmacokinetics: What the body does to the drug  Studies the FATE of drugs once ingested and the variability of drug response in varying patient population  Includes absorption, distribution, metabolism/biotransformation and excretion of drugs. Pharmacodynamics: What drugs do to the body : the mechanism of drug action in living tissues  Drug-Receptor Interactions  Dose-Response  Effect of drug  Mechanism of action RELATIONSHIP-KINETICS AND DYNAMICS Dosage regimen Absorption Distribution pharmacokineti Metabolism cs excretion concentration in plasma pharmacodynami cs concentration at the site of action effect  SUB-DIVISIONS/BRANCHES Toxicology:  Toxicology is the study of the harmful or toxic effects of chemicals (drugs) on living systems. It is also concerned with the symptoms and treatment of poisoning. Pharmacotherapeutics  It’s the study of how drug may be used in the treatment of disease.  Which among the drugs would be most effective or appropriate for a specific disorder or what dose would be required.  Use of drugs for prevention and cure of diseases - clinical management of diseases. Pharmacogenetics  Area of pharmacology concerned with unusual responses to drugs caused by genetic differences between individuals.  E.gs. Differences in Enzyme Activity, Acetylation polymorphism, and Cytochrome P450 aberration, etc.  SUB-DIVISIONS/BRANCHES Pharmacoepidemiology:  The study of the effects of drugs on populations.  It is concerned with the variability of drug effects between individuals in a population, and between populations.  It takes into account patient compliance and other factors that apply when the drug is used under real-life conditions. Pharmacogenomics  This describes the use of genetic information to guide the choice of drug therapy on an individual basis.  The underlying principle is that differences between individuals in their response to therapeutic drugs can be predicted from their genetic make-up.  SUB-DIVISIONS/BRANCHES Chemotherapy:  It is the branch of therapeutics which is concerned with the effects of drugs upon microorganisms and parasites, living or multiplying in a living organism.  It also includes the drugs used in malignancy (cancer). Behavioral pharmacology  Studies the effects of drugs on behavior. Biochemical and Cellular pharmacology  Uses the methods of biochemistry, cell biology, and cell physiology to determine how drugs interact with, and influence, the chemical "machinery" of the organism. Clinical pharmacology  The study of pharmacodynamics and pharmacokinetics in humans (Patient and volunteers). SUB-DIVISIONS/BRANCHES Psychopharmacology  Is the field of psychology and psychiatry dedicated to the study of drug’s effects on mood and behavior.  Of particular interest is the study of the effectiveness, dosing, and indications for psychoactive drugs Veterinary pharmacology  Concerns the use of drugs for diseases and health problems unique to animals. Molecular pharmacology  Deals with the biochemical and biophysical characteristics of interactions between drug molecules and those of the cell. SUB-DIVISIONS/BRANCHES Systems and Integrative Pharmacology  Is the study of drug action and toxicity in the whole animal. Neuropharmacology  The study of drugs that modify the functions of the nervous system, including the brain, spinal cord, and the nerves that communicate with all parts of the body. Endocrine pharmacology  The study of actions of drugs that are either hormones or hormone derivatives, or drugs that may modify the actions of normally secreted hormones. Cardiovascular pharmacology  Concerns the effects of drugs on the heart, the vascular system, and those parts of the nervous and endocrine systems that participate in regulating cardiovascular function. END