introduction to pharmacology. drug any chemical that affects the physiological processes of a living...

introduction to pharmacology

Drug

Any chemical that affects the physiological processes of a living organism

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Pharmacology

The study or science of drugs

History of Drugs

• In Primitive times – Herbal Remedies– Arrow Poisons– Mood altering foods

• Opium • Cocoa

Were used.

These were derived from roots, bark,leaves and berries

History of Drugs (cont.)

• 17th and 18th Century– Increased knowledge of drugs and shared

with world as increase in world travel continued

– Widely accepted by physicians and lay persons

History of Drugs (cont.)

• 19th Century– The beginning of the modern science of

pharmacology– Problems Recognized

• Dose – effect relationship• Processes involved in absorption/excretion• Localization of the site of action of a drug• Specific mechanisms of drug action• Relation between chemical makeup & biologic activity of

substances

History of Drugs (cont.)

• Developed– Anesthetics– Injection technique– Antipyretics (Aspirin)

History of Drugs (cont.)• Modern Medicine

– Complex science – Big business– Virtually every body function can be enhanced,

suppressed, or manipulated by chemical means– Problem with drug abuse worldwide

• We need to use this new technology wisely; without poisoning ourselves and environment

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Drug Names

Chemical name• Describes the drug’s chemical composition and

molecular structure

Generic name (nonproprietary name)• Name given by the United States Adopted

Name Council

Trade name (proprietary name)• The drug has a registered trademark; use of the

name restricted by the drug’s patent owner (usually the manufacturer)

Drug Names (cont'd)

Chemical name• (+/-)-2-(p-isobutylphenyl) propionic acid

Generic name• ibuprofen

Trade name• brufen®

Drug Classification

• By chemistry– electrolytes

• By mechanism– Beta blockers– benzodiazepines

• By disease– antihypertensives– Antiemetics

Components of a Drug Profile

• Names• Classification• Mechanism of

Action• Pharmacokinetics• pharmacodynamics• Indications• Contraindications

• Side Effects• Interactions• Routes of

Administration• Dosage

activity

• In groups of 5

-list 5 properties you expect a ‘good’ drug to have

Properties of an Ideal Drug

• Effectiveness– A drug that elicits the response it was meant to.

• Safety– Pharmakon= poison in Greek– Safe even at high concentrations and for long periods of

administration • Reduced by proper administration (iv, ip, im, sc, etc…)• No habit forming aspects• No 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

• Drowsiness can be caused by antihistamines• Constipation, urinary hesitance, and respiratory

depression can be caused by morphine

Properties of an Ideal Drug

• Reversible action– Effects be reversible, i.e., removal/subside within specific time– Example: Contraceptives, which are used in family planning

should have the property that fertility should be restored soon once the contraceptive is stopped

• Ease of Administration– Number of doses should be low and easy to administer

• A drug to be taken every 3 hourly is difficult to administer• Insulin for diabetic patients should be given as SC

injections .It is not a pleasant experience

Additional Properties of Ideal Drug (Continued)

• less drug interactions – Should not augment or decrease action of other drugs or have

adverse combined effects• Respiratory depression caused by diazepam (valium),

which is normally minimal, can greatly be intensified by alcohol.

• Low Cost– Easy to afford (especially with chronic illness)

• Growth hormone costs between abot Rs. 100000/= per month

• Lifelong medication: hypertension, arthritis, diabetes

Additional Properties of Ideal Drug (Continued)

• Chemical Stability– Not losing of effectiveness with storage

Because No Drug is Ideal……..

• Because no drug is ideal…….– No drug is safe– All drugs produce side effects– Drug responses may be difficult to predict– Drugs may be expensive– Drugs may be hard to administer

• All members of health care team must exercise care to promote therapeutic effects and minimize drug induced harm

Pharmacologic Principles

• Pharmaceutics

• Pharmacokinetics

• Pharmacodynamics

• Pharmacotherapeutics

• Pharmacognosy

Pharmaceutics

The study of how various drug forms influence pharmacokinetic and pharmacodynamic activities

Figure 2-1 The chemical, generic, and trade names for the common analgesic ibuprofen are listed next to the chemical structure of the drug.

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Pharmacokinetics

• The study of what the body does to the drug– Absorption– Distribution– Metabolism– Excretion

Pharmacognosy

The study of natural (plant and animal) drug sources•Natural sources of drugs:

– Plants: Alkaloids >>Morphine– Microbes: Antibiotics >> Penicillin,

streptomycin– Animal tissues: Hormones>> growth hormone – Minerals: Lithium (Psychotherapy)

Pharmacodynamics• The study of what the drug does to the

body– The mechanism of drug actions in living

tissues

Pharmacodynamics: Mechanisms of Action

• Receptor interaction

• Enzyme interaction

• other

Mosby items and derived items © 2005, 2002 by Mosby, Inc.

Drugs act by forming a chemical bond with specific receptor sites, similar to a key and lock. B, The better the “fit,” the better the response. Those with complete attachment and response are called agonists. C, Drugs that attach but do not elicit a response are called antagonists. D, Drugs that attach, elicit a small response, and also block other responses are called partial agonists or agonist-antagonists.

Pharmacotherapeutics

The use of drugs and the clinical indications for drugs to prevent and treat diseases

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Pharmacotherapeutics: Types of Therapies

• Acute therapy• causal therapy• Maintenance therapy• Supplemental therapy• Palliative therapy• Supportive therapy• Prophylactic therapy• Empiric therapy

Causal treatment•  treatment directed against the cause of a

disease.• conservative treatment  that designed to

avoid radical medical therapeutic measures or operative procedures.

• expectant treatment  treatment directed toward relief of unpleasant symptoms, leaving cure of the disease to natural forces.

• palliative treatment  treatment designed to relieve pain and distress with no attempt to cure.

• preventive treatment , prophylactic treatment that in which the aim is to prevent the occurrence of the disease; prophylaxis.

Active therapy

• Short-term medical treatment, usually in a hospital, for patients having an acute illness or injury or recovering from surgery.

• directed immediately to the cure of the disease or injury.

Maintenance therapy

Treatment given to sustain level of disease control

Ex-asthmatic patients are put on long term steroid inhalers to maintain disease control and prevent acute attacks

Palliative therapy

• Treating a disease which is unable to cure with drugs to comfort the patient and give symptomatic relief

Ex-morphine for terminal cancer patients

Supportive therapy

• Any form of treatment intended to relieve symptoms or help the patient live with them rather than attempt changes in the disease course

Ex-taking paracetamol for a pneumonia will comfort as the fever and pain will go down, but disease will not be cured

• empiric treatment  treatment by means which experience has proved to be beneficial.

Prophylactic therapy

• Administration of a drug in the absence of known disease, to reduce the occurrence of the disease

• Ex- antibiotics given after surgery to prevent post op infections

Monitoring

• The effectiveness of the drug therapy must be evaluated

• One must be familiar with the drug’s:– Intended therapeutic action (beneficial)– Unintended but potential side effects

(predictable, adverse reactions)

Monitoring (cont'd)

• Therapeutic index

• Drug concentration

• Patient’s condition

• Tolerance and dependence

• Interactions

• Side effects/adverse drug effects

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Monitoring (cont'd)

• Tolerance – A decreasing response to repetitive

drug doses

Monitoring (cont'd)

• Dependence – A physiologic or psychological need for a

drug

Monitoring (cont'd)

Interactions may occur with other drugs or food• Drug interactions: the alteration of action of a drug by:

– Other prescribed drugs– Over-the-counter medications– Herbal therapies

Monitoring (cont'd)

• Medication misadventures– Adverse drug events– Medication errors

Other Drug-Related Effects

• Teratogenic

• Mutagenic

• Carcinogenic

Toxicology

The study of poisons and unwanted responses to therapeutic agents

Questions…

Thank you…