Introduction to pharmacology

INTRODUCTION TO PHARMACOLOGY(PP I)

Dr. Mohammed Qasim Module Moderator of Principles of Pharmacology

Dept. of Pharmacology Baghdad College of Medicine

Learning ObjectivesAt the end of my lecture you should be able to
Define the terms used in Pharmacology, including Pharmacokinetics, Pharmacodynamics

List the different nomenclature of drugs on certain bases Give a brief description about what we will learn in pharmacology module Know how to chose an ideal drug therapy for treatment

PHARMACOLOGY

(Greek “Pharmacon” – drug, “logos” - teaching) The science that studies the interaction of the chemical substances with live organisms, drugs administration for treatment and prophylaxis of various diseases and pathological processes

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 excretion 3. Clinical Pharmacology: study of drugs in humans (patient and volunteers) 4. Therapeutics: use of drugs to diagnose, prevent and treat illness (and/or pregnancy)= medical use of drugs


Brand – original drug which is defended by patent and may be produced during patent term only by this pharmaceutical firm Generic – when term of patent is discontinued the drug may be produced by different pharmaceutical companies under new product (trade) names but at the basis of original active substance (similar quantity, route of administration etc.) All generics are much more cheaper compared to brands, that is the main reason – why they are so popular among the patients


Names of Drugs
The generic name: is given for the drug to being official name. The official (scientific)name: is the name under which its listed in one in the official publication. The chemical name: is the name by which the chemist knows it. The trade mark or brand name (proprietary name) : is name given by the drug manufacture Example: hydrochlorothiazide (official name). Esidrex (brand name)

SE (side effects) and complications of drugs

200 000 people in U.S.A. die from side effects of drugs annually 76,6 billion $ are spared in U.S.A. annually to treat complications attached to drugs usage

Take 5th place among causes of mortality on the Earth after cardiac-vascular diseases, malignant tumors, lungs diseases, traumas

Medical mistakes in clinics

- overdosing - administration of drugs to patients with allergy - mixing up names of the drugs

focomelia

Thalidomide (katergan)

Definitions

Pharmacology: is a science that studies the effect of the drugs on the body. Pharmacopeias: are the total of all authorized drugs available within the country. Medication: is a substance administered for diagnosis, cure, treatment or prevention. Prescription: the written direction for the preparation and the administration of the drug.


The therapeutic effect: is the primary effect intended that is the reason the drug is prescribed such as morphine sulfate is analgesia. Side effect: secondary effect of the drug is one that unintended, side effects are usually predictable and may be either harmless



Drug toxicity: deleterious effect of the drug on an organism or tissue, result from overdose or external use. Drug allergy: is immunological reaction to a drug.


Drug interaction: occur when administration of one drug before or after alter effect of one or both drug. Drug misuse: Is the improper use of common medications in way that lead to acute and chronic toxicity for example laxative, antacid and vitamins.


Drug abuse: is an inappropriate intake of substance either continually or periodically. Drug dependence: is a persons reliance on or need to take drug or substance there are two type of dependence:

There are two type of dependence:

Physiological dependence: is due to biochemical changes in the body tissue these tissue come to require substance for normal function. Psychological dependence: is emotional reliance on a drug to maintain a sense of wellbeing accompanied feeling of need.

Drug habituation: denotes a mild form of psychological dependence. Illicit drug: also called street drug are those sold illegally.

basic concepts of Pharmacology

Pharmacokinetics: is a bout how the body deal with drug. Pharmacodynamics: is effect of drug on the body. Pharmacotherapeutics: is a clinical using of drug. Pharmacognosy: The study of natural (plant and animal) drug sources.

PHARMACOKINETICS

THE PART OF PHARMACOLOGY THAT CONCERNED WITH THE ABSORBTION, DISTRIBUTION, METABOLISM (BIOTRANSFORMATION) AND EXCRETION OF DRUGS WHAT THE ORGANISM DOES TO THE DRUGS

PHARMACODYNAMICS

THE PART OF PHARMACOLOGY THAT CONCERNED WITH THE BIOCEMICAL AND PHYSIOLOGICAL EFFECTS OF DRUGS AND THEIR MODE OF ACTION IT INCLUDES THE DOSE-EFFECT RELATIONSHIP, FACTORS MODIFYING DRUG EFFECTS, DOSAGE, DRUG TOXICITY WHAT DRUGS DO TO THE ORGANISM

ONSET – the period between the moment of drug introduction to the organism and the beginning of its actionDURATION OF DRUG ACTION – the period then specific effects of the drug are maintainedWIDENESS of therapeutic action (therapeutic window) – the distance between minimum therapeutic and minimum toxic doses of drug

Properties of Ideal Drug

Effectiveness: A drug that elicits the response it was meant to. It is the most important property. No effect=no justification of use (FDA(food and drug administration) approved with appropriate experiments). Safety:Pharmakon= poison in GreekSafe even at high concentrations and for long periods of administration (no such thing as a safe drug)Reduced by proper administration (iv, ip, im, sc, etc…)No habit forming aspectsNo side effects ( excessive dosage of opioid analgesics carries a risk of respiratory failure, cancer drugs increase infections,aspirin causes gastric ulcer etc…)

Properties of Ideal Drug

Selectivity: One that elicits only the response for which it is given Selective for specific reaction with no side effects (there is no such thing) Drowsiness can be caused by antihistamines Morning sickness, cramps, and depression can be caused by oral contraceptives Constipation, urinary hesitance, and respiratory depression can be caused by morphine

Additional Properties of Ideal Drug (no drug is ideal!)

1. Reversible action 2. Predictability 3. Ease of Administration 4. Freedom from drug interactions 5. Low Cost 6. Chemical Stability

Therapeutic Objective

To provide maximum benefit with minimum harm Factors that determine Intensity of Response Administration- dosage size and route Pharmacokinetic processes Pharmacodynamics Individual Variations

Therapeutic Objective

1. Administration- dosage size and route - Because of errors in administration routes and dosage and at wrong time there are many discrepancies in what patient gets and could cause more harm than good - Errors could be made by pharmacists, physicians, or nurses - Should give patients complete instruction about their medication and how to take it 2. Pharmacokinetic processes - Determines how much of an administered dose gets to its sites of action 1) drug absorption 2) drug distribution 3) drug metabolism 4) drug excretion


Therapeutic Objective(continued)
3. Pharmacodynamics Once a drug has reached its site of action, pharmacodynamic processes determine the type of response and intensity -Drug must first bind to its specific target site at (RECEPTOR) that may be a chemical, a protein on a cell or in blood or tissue spaces, or on a bacteria or virus (i.e., heparin, antibody, leukotriene receptor (new), penicillin, etc…)-Followed by a sequence of events that result in response (inhibition of clotting, inhibition of peptidoglycan synthesis, inhibition of inflammation, blocking of virus, etc…). - Functional state of the patient is also important- Tolerance to morphine will cause less of a response & placebo effects may help determine response

Therapeutic Objective(continued)

4. Sources of individual variationEach patient is unique in ability to respond and to how they each respond, but formation of “IDEAL DRUG” will lessen this variationAge- very important factorSex- due to hormonal differencesWeight- less effective and longer lasting in obese individuals (storage in fat)Kidney & liver functions - elimination of drugGenetic variables- tolerance, allergy (though not always genetic)