Nursing introduction to Pharmacology-Lecture PDF

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Summary

Introduction into pharmacology in nursing covering the basics of the pharmacology principles and more, definitions, terms etc...

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Knowing how drugs works make these tasks easier to handle, thus enhancing drug therapy.

Introduction to Nursing Pharmacology A.

B.

o o

Introduction to Drugs

The human body works through a complicated series of chemical reactions and processes.

History

o

Early drug – plants, animals & minerals 2700 BC – earliest recorded drug use found in Middle East & China 1550 BC – Egyptians created Ebers Medical Papyrus

Castor oil – laxative Opium – pain

Drugs are chemicals that are introduce into the body to cause some sort of change. 

Drugs will undergo process with in the body which involve breaking and eliminating the drugs, in turn affect the body’s complex series of chemical reactions.

Understanding how drugs act on the body to cause changes and applying that knowledge in the clinical setting are important aspects of nursing practice. The nurse is in a unique position regarding drug therapy because nursing responsibilities include the following:

Moldy bread – wounds & bruises  

1st set of drug standards & measurements (grains, drams, minims), currently being phased out  

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Administering drugs Assessing drug effects Intervening to make the drug regimen more tolerable Providing patient teaching about drugs and drug regimen. Monitoring the overall patient care plan to prevent medication error

Galen (131-201 AD) Roman physician; initiated common use of prescriptions 1240 AD – introduction of apothecary (pharmacy) system (Arab doctors)

15th century – apothecary shops owned by barber, surgeons, physicians, independent merchants 18th century – small pox vaccine (by Eward Jenner, British Doctor)

Digitalis from foxglove plant for strengthening & slowing of heartbeat Vitamin C from fruits 

19th century – morphine & codeine extract from opium

Introduction of atropine & iodine

2. Pharmacokinetics – deals with the absorption, distribution, biotransformation & excretion of drugs

Amyl nitrite used to relieve anginal pain   

Discovery of anesthetics (ether, nitrous oxide) Early 20th century – aspirin from salicylic acid - Introduction of Phenobarbital, insulin, sulforamides

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ex: penicillin from penicillium (fungi) 3. Pharmacotherapeutics – study of drugs used in the diagnosis, prevention, suppression, & treatment of diseases

Mid-20th century

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1940 – Discovery antibiotics (penicilline, tetracycline,streptomycin), antihistamines, cortisone

4. Pharmacognonsy – study of drugs in their original unaltered state; origin of drugs

1950 – Discovery antipsychotic drug, antihypertensives, oral contraceptives, polio vaccine

C. -

5. Toxicology – study of biologic toxins: study of poison & its effects deals with deleterious effects of physical & chemical agents (including drugs) in human

Pharmacology

Is the study of the biological effects of chemicals

It is the scientific study of the origin, nature, chemistry, effects and uses of drugs. In clinical practice, health care providers focus on how chemicals act on living organisms.

Nurses deal with Pharmacotherapeutics, or Clinical Pharmacology, the branch of pharmacology that uses drugs to treat, prevent, and diagnose diseases.

Clinical Pharmacology -

Addresses two key concerns  

Subdivisions of Pharmacology 1. Pharmacodynamics – study of the biochemical & physiological effects of drugs & mechanisms of action o what the drug does to the body

what the body does to the drug deals with beneficial effects of the drugs (medicines) source of drugs

The drug’s effects on the body The body’s response to the drug

Because drug can have many effects the nurse must know which ones may occur when a particular drug is administered.

Effects of the Drug

1.

2.

Therapeutic Effect



- The primary effect intended, that is the reason the drug is prescribed.



- Also called desired effect.

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Side Effect - The effect of the drug that is not intended.

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Drug Antagonism – the conjoint effects of two drugs is less than the drugs acting separately. Summation – The combined effect of two drugs produces a result that equals the sum of the individual effect of each agent. Synergism – The combined effects of drugs is greater than the sum of each individual agent acting independently. Potentiation – The concurrent administration of two drugs in which one increases the effect of the other drug.

Therapeutic Effects of Drugs

- Also called secondary effect. 1. 3.

Relieves the symptoms of a disease but not affect the disease itself.

- The immunologic reaction to the drug. 4.

Anaphylactic Reaction - A severe allergic reaction which usually occurs immediately following administration of the drug.

5.

Palliative

Drug Allergy

2.

Ex. Analgesic for pain Curative

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Treats the disease condition

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Ex. Antibiotic for infection

Drug Tolerance - A decreased physiologic response to the repeated administration of a drug or chemically related substance. Excessive increase in the dosage is required in order to maintain the desired therapeutic effect.

3.

Supportive Sustains body functions until other treatment of the body’s response can take over.

6.

Drug Interaction - Effects of one drug are modified by the prior or concurrent administration of another drug, thereby increases or decreases the pharmacological action.

Ex Mannitol to reduce/ICP in a client for surgery due to brain tumor. 4.

Substitutive

5.

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Replaces body fluids or substances.

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Ex. insulin injection for diabetes mellitus

E.

Chemotherapeutic

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Destroys malignant cells

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Ex. Cyclophophamide for cancer of the prostate gland. 6.

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Restorative Returns the body to health.

D.

Drug Nomenclature 1. CHEMICAL NAME – atomic/molecular structure of drug 

Ex. acetylsalicylic acid

2. GENERIC NAME/NON-PROPERTY NAME – original designation given to the drug when the drug company applies for approval patents   

universally accepted & not capitalized; before drug becomes official, used in all countries protected by law; not capitalized ex. aspirin

3. TRADE/BRAND/PROPRIETY NAME – name given by the drug company that developed it 

followed by the symbol R or TM, 1st letter is capitalized

ex. Aspilet

Sources of Drugs

1. Plants – roots, bark, sap, leaves, flowers, seeds of medicinal plants  

digitalis (use as a heart stimulant) from wildflower, purple foxglove, dried leaves of plant active principles of plants o alkaloids – alkaline in reaction, bitter in taste, powerful in physiologic activity o atropine & scopolamine o morphine sulfate, cocaine, quinine, nicotine, caffeine o procaine o glycosides – digitalis o resin – soluble in alcohol; example – colonic irritant found in laxative cascara o gums – used in bulk-type laxatives: some used in certain skin preparations for their soothing relief o oils – castor oil, oil of wintergreen

2. Animal Products – from organs, organ secretion or organ cells o Used to replace human chemical not produces because of disease or genetic problems o Thyroid drugs & growth hormones preparations – from animal thyroid & hypothalamus tissue (many of these preparations are now created synthetically – safer & purer) o Insulin – from pancreas of animals (hog, cattle, sheep): thru genetic engineering – cld produce human insulin by altering E. coli bacteria making it a better product without impurities that come with animal products

3. Inorganic Compounds – from free elements, both metallic & non-metallic usually in form of acids bases, salts found in food      

Dilute HCI – control/prevent indigestion Calcium, aluminum, fluoride, iron, gold, potassium more potent, more stable, less toxic steroids – arthritis & other diseases sulfonamides/chemotherapeutic agents – kill microorganism slow their growth meperidine HCI (Demerol)

4. Synthetic Sources – many drugs developed synthetically after chemical in plants, animals, or environment have been screened for signs of therapeutic activity

Vaccine & serums, antifungals, antihistamines, antineoplastics, antacids 2. By Body System o

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4.1 Genetic engineering – alter bacteria to produce chemicals that are therapeutic and effective. 

Reordering of genetic information enables scientists to develop bacteria that produce insulin for human.

4.2 Chemical alterations – Scientists alter chemical with proven therapeutic effectiveness to make it better. 

F.

CNS – (+)/(-) actions of neural pathways & centers; ex. Phenobarbital ANS – governs several bodily functions so that drugs that affect ANS will at the same time affect other systems functions; ex. scopolamine GIT – acts on muscular & glandular tissues; ex. loperamide Respiratory System – act on resp. tract, tissues, cough center, suppress, relax, liquefy & stimulate depth & rate of respiration; salbutamol Urinary system – act on kidney & urinary tract; ex. furosomide Circulatory system – act on heart, blood vessels, blood; ex. Metroprolol

Sometimes a small change in a chemical’s structure can make that chemical more useful as a drug, more potent, more stable, less toxic.

G. 1.

Prescription Drugs -

Also known as legend drugs

Can be dispensed if with prescription order; with specific name of drug & dosage regimen to be used by patient.

Drug Classification

1. By Action o Ant- infective – antiseptics, disinfectants, sterilants o Antimicrobials, metabolic, diagnostic materials, vitamins & minerals

Kinds of Drugs

2.

Non-Prescription Drugs -

Also known as Over – the – Counter Drugs

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can be dispensed without prescription order

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for self-treatment of variety of complaints

Vitamin supplements, cold/cough remedies, analgesics, antacids, herbal products Cautions in use of OTC drugs:         

Delay in professional diagnosis & treatment of serious/potentially serious condition may occur Symptoms may be masked making the diagnosis more complicated Clients’ health care provider/pharmacist should be consulted before OTC preparations are taken Labels/instructions should be followed carefully Ingredients in OTC drug may interact with prescribed drug Inactive ingredients may result in adverse reactions Potential for overdose Multiple medication users are at risk as more medications are added to therapy regimen Interactions of medications are potentially dangerous

3.

Investigational drug -

4.

new drugs undergoing clinical trails Illicit/street drug

used/distributed illegally for non-medical purposes to alter mood of feeling

o “lock and key theory” o Drug action may be:

Drugs and the Body (Pharmacodynamics) Pharmacodynamics - The study of the drug mechanisms that produce biochemical or physiologic changes in the body. - What happens to the body in response to the drug. - Interactions between chemical components of living systems & foreign chemicals including drugs that enter these systems.

Drug Actions: a. To replace or act as substitutes for missing chemicals. b. To increase or stimulate certain cellular activities. c. To depress or slow cellular activities. d. To interfere with the functioning of foreign cells, such as invading microorganisms or neoplasm.

Theories of Drug Actions A. Drug Receptors Interaction o Receptor sites – location on a cell surface where certain molecules such as enzymes, hormones, drugs attach to interact with cell component. o Receptor sites react with certain chemicals to cause an effect within the cell.

1. Agonist • Drugs interact directly with receptor sites to cause the same activity that natural chemicals would cause at that site. • Ex. Insulin 2. Antagonist • A drug has an affinity for a receptor but displays little or no intrinsic activity. A. Competitive antagonist o Competes with the agonist for receptor sites B. Non-competitive antagonist o Binds to receptor sites and blocks the effects of the agonist B. Drug Enzyme Interactions o Interferes with enzyme systems that act as catalyst from various chemical reactions. o Enzyme systems:  Cascade effect; one enzyme activating another, causing cellular reaction.  If single step in one of enzyme system is blocked, normal cell function is disrupted o Ex. ACE inhibitors, inhibiting the release of angiotensin converting enzyme in the lungs, preventing the conversion of Angiotensin I to Angiotensin II which is a powerful vasocontrictor, preventing an increase in blood pressure.

C. Selective Toxicity o All chemotherapeutic agent would act only on 1 enzyme system needed for life of a pathogen or neoplastic cell & will nor affect healthy cells. o Ex. Penicillin

Classifications of Drug Action (in terms of speed of action) a. Rapid o few seconds to minutes. o intravenous, sub-lingual, inhalation b. Intermediate o 1-2 hours after administration o intramuscular, subcutaneous c. Delayed/Slowed o Several hours after administration o oral and rectal

Parameters of Drug Action Parameters – notable characteristics a. Onset of action o Latent period, interval between time the drug is administered and 1st sign of its effect. b. Duration of action o Period from onset until drug effect is no longer seen. o Length of time the drug exerts pharmacologic effect. c. Peak of action o drug reaches its highest blood / plasma concentration d. Termination of action o point from onset at which drug effect is no longer seen

o Through the muscle o Through subcutaneous tissues

Drugs and the Body (Pharmacokinetics) Drugs and the Body I. Pharmacokinetics - The term kinetics refers to movement. - Pharmacokinetics deals with a drugs actions as it moves through the body - What happens to the drug when it enters the body. - Involves the study of the following: o Absorption o Distribution o Metabolism/Biotransformation o Excretion

A. Absorption - In order to reach reactive tissues, a drug must first make its way into the circulation. - Absorption refers to what happens to a drug from the time it is introduced to the body until it reaches the circulating fluids. - Drugs can be absorbed from many different areas in the body: o GIT o Mucous membranes o Through the skin o Through the lungs

A. Cell Absorption - Drugs can be absorbed into cells through various processes 1. Passive Absorption (diffusion) o Movement of drug particles from an area of higher concentration to an area lower concentration. o No energy required: occurs when smaller molecules diffuse across membrane o Stops when drug concentration on both sides of the membrane is equal o Major process through which drugs are absorbed into the body o Oral drugs use passive transport

2. Active Absorption o Movement of drugs particles from an area of low concentration to an area of high concentration. o Energy is required o Used to absorb electrolytes (Ex. sodium, potassium) 3. Pinocytosis o Cells engulf the drug to carry it across the membrane. o Transport fat-soluble vitamins (vitamin A,D,E,K) B. Factors Affecting Drug Absorption: 1. Blood Flow 2. Pain 3. Stress 4. Foods (High fat and solid foods)

5. Exercise 6. Solubility 7. Nature of the absorbing surface 8. pH 9. Concentration 10. Dosage form

- the drug can remain free or bind to protein - Portion of drug bound to protein is inactive, no therapeutic affect

c. Oral Administration of Drug

2. Highly protein bound drug  89% of drug is bound to protein  diazepam, piroxicam, valproic acid

B. Distribution - Process by which drug becomes available to body fluids & tissues - The ways a drug is transported from the site of absorption to the site of action (transportation) - Happens in the circulation (circulatory system) A. Factors Affecting Distribution 1. Size of the organ 2. Blood flows  drug is quickly distributed to organs with large supply of blood (heart, liver, kidneys)  distribution to other internal organs, skin, fat, muscle is slower 3. Solubility  Lipid-soluble or non-lipid-soluble  Lipid-soluble drugs can cross the blood-brain barrier & enter the brain 4. Protein binding

1. Free/unbound portion  (+) pharmacologic response

3. Moderately high protein bound drugs  61-89% bound protein  Erythromycin, phenytoin

4. Moderately protein bound drugs  30-60% bound to protein  aspirin, lidocaine, pindolol, theophyline 5. Low protein-bound drugs  30% bound to protein  amikacin, amoxicillin

C. Metabolism/Biotransformation B. Protein Binding - as drug travels through the body, it comes in contract with proteins (albumin)

- Also called detoxification. - Refers to the body’s ability to change a drug from its dosage form

to a more water soluble form that can be excreted - A sequence of chemical events that change a drug to a less active form after it enters the body - Permits the body to inactivate a potent drug before it accumulates & produces toxic effects - Drugs can be metabolized several ways: o Most drugs metabolized into inactive metabolites (products of metabolism), which are then excreted o Other drugs converted to active metabolites – capable of exerting their own pharmacologic action  May undergo further metabolism or may be excreted from body unchanged  Pro-drugs – some drugs administered as inactive drugs which don’t become active until they’re metabolized A. Sites of Metabolism 1. Liver  Through the drug metabolizing enzymes (microsomal enzymes, non-microsomal enzymes)  1st pass effect/hepatic 1st pass – some drugs do not directly go into circulation but pass thru intestinal lumen to liver via portal vein 2. Plasma 3. Kidneys 4. Membranes B. Factors Affecting Drug Metabolism 1. Diseases  Liver cirrhosis and heart failure 2. Genetics  People metabolize drugs rapidly, other more slowly. 3. Environment  Smoking and stressful environment

4. Age  Infants have immature livers that reduce the rate of metabolism.  Elderly patients experience a decline in liver size, blood flow and enzyme production that also slows metabolism 5. Nutrition  Liver enzymes involved in metabolism rely on adequate amounts of amino acids, lipids, vitamins and carbohydrates. 6. Insufficient amounts of major body hormones  Decrease amounts of insulin and adrenal corticosteroids can reduce metabolism of drugs in the liver.

D. Excretion - Removal of drug from the body - Is the process by which drugs are eliminated from the body - Drug is changed into inactive form & excreted by the body A. Sites of Excretion 1. Kidney  Free/unbound/water soluble drugs are filtered in kidneys  Protein bound drug cannot be filtered in kidney 2. Lungs, exocrine (sweat, salivary, mammary) glands, skin, intestinal tract B. Factors Affecting Excretion 1. Urine pH  Normal urine pH is 4 – 5.8  Acidic urine promotes elimination of weak base drugs • Ex. Cranberry j...