NURS 320 Pharmacologic Principles

Course Information

• Course name: NURS 320 Pathophysiology and Pharmacology I
• Resource: Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

Welcome Back!

• Introductions
• Syllabus
• Pharmacologic Principles
• Life-Span Considerations
• Review of Math Competency

Definitions

• Pathophysiology: The study of the underlying changes in body physiology that result from disease or injury. (Abnormal is normal)
• Drug/Medications: Any chemical that affects the physiologic processes of a living organism.
• Pharmacology: The study or science of drugs.

Drug Names

• Chemical name: Describes the drug's chemical composition and molecular structure.
• Generic name (nonproprietary name): Given by the United States Adopted Name Council; lower case letters.
• Trade (Brand) name (proprietary name): Drug has a registered trademark; use of the name is restricted by the drug's patent owner (usually the manufacturer); upper case letters.

Specific Example

• Chemical name: (+/-)-2-(p-isobutylphenyl) propionic acid
• Generic name: ibuprofen
• Trade name: Motrin, others

Drug/Medication Classifications

• Chemical Structure
• Therapeutic Use
• Effects on Body Systems

Pharmacologic Principles

• Pharmaceutics
• Pharmacokinetics
• Pharmacodynamics
• Pharmacotherapeutics

Pharmaceutical Phase

• Drugs dissolve in the body
• Disintegration of dosage form
• Dissolution of drug in body

Pharmacokinetics Phase

• Absorption, distribution, metabolism, excretion
• Absorption- drug is moved through out the body
• Distribution- how drug moves to tissues in the body
• Metabolism- how the drug is processed within the body
• Excretion- how the drug is removed from the body

Pharmacodynamics Phase

• Drug-receptor interaction
• Drug effect

Pharmaceutics

• Dosage forms (liquid, capsules, tablets, EC tablets, powder, inhalant, IM, SQ, IV)
• Dosage form design affects dissolution
• Enteric-coated tablets: Coating protects drug from stomach acid, allowing for slower absorption in intestines. Avoid crushing.
• Extended-release: Prolongs drug absorption and duration of action. Avoid crushing.

Drug Absorption of Various Oral Preparations

• Fastest: Liquids, elixirs, syrups, suspension solutions
• Slowest: Enteric-coated tablets

Various Oral Preparations

• Extended Release- prolongs drug absorption and duration of action
• Immediate Release - immediate response
• Enteric Coated- coating protects from stomach acid
• Capsules- can be opened usually
• Avoid crushing or breaking extended release and enteric-coated products

Pharmacokinetics

• Study of what the body does to a drug
• Absorption
• Distribution
• Metabolism (liver)
• Excretion (kidneys)

Pharmacokinetics: Absorption

• Movement of drug from administration site into bloodstream
• Bioavailability: How much medication is available for absorption
• Extent of drug absorption (Orally less than 100%, IV = 100%)
• Bioequivalency: Two drugs with same bioavailability have same effect
• First-Pass effect: Oral administration, drug metabolized by liver before reaching systemic circulation

First-Pass Effect and Metabolism

• Metabolism of drug and passage through liver
• Oral route extensively metabolized by liver
• IV route bypasses liver reducing first-pass effect.

First Pass vs. Non-First Pass Effects

• Oral, NG/DHT/FT/G-tube, Hepatic artery, Rectal
• Aural, intraocular, buccal/SL, inhaled, intra-nasal, transdermal, IV, intra-arterial, IM, SQ, vaginal

Routes

• Enteral (GI tract): Oral, sublingual, buccal, rectal
• Parenteral (outside GI tract): IV, IM, subcutaneous, intradermal, intra-arterial, intrathecal, intraarticular, transdermal
• Topical: Skin (including transdermal patches), eyes, ears, nose, lungs (inhalation), rectum, vagina

Enteral Route

• Drug absorbed into systemic circulation through oral or gastric mucosa or small intestine
• Oral, Sublingual, Buccal, Rectal

Parenteral Route

• Intravenous, Intramuscular, Subcutaneous, Intradermal, Intra-arterial, Intrathecal, Intraarticular, Transdermal

Topical Route

• Skin
• Eyes
• Ears
• Nose
• Lungs (inhalation)
• Rectum
• Vagina

Factors Affecting Absorption

• Food and fluids with drug
• Dosage formulation
• Absorptive surface status
• Blood flow rate to small intestine
• Stomach acidity
• GI motility

Distribution

• Transport of drug in bloodstream to its action site
• Protein binding
• Water-soluble vs. fat-soluble
• Blood-brain barrier
• Areas of rapid distribution: heart, liver, kidneys
• Areas of slow distribution: muscle, skin, fat

Metabolism/Biotransformation

• Biochemical alteration of drug into inactive metabolite (in liver mainly).
• Liver (main organ), cytochrome P450 (CYP enzymes)
• Skeletal muscle, kidneys, lungs, plasma, intestinal mucosa
• Enzyme inhibitors/inducers affect activity
• Factors decreasing metabolism: cardiovascular dysfunction, renal insufficiency, starvation (etc)
• Factors increasing metabolism: fast acetylator, barbiturate, rifampin therapy.

Excretion

• Elimination of drugs from the body
• Kidneys (main organ)
• Bowel (fecal matter)
• Liver (enterohepatic recirculation, bile)
• Lungs
• Skin

Half-life

• Time to remove half of original drug amount from body
• Measure of drug removal rate
• Most drugs effectively removed after about 5 half-lives
• Steady state achieved when amount of drug removed equals amount absorbed

Onset, Peak, and Duration

• Onset: Time drug elicits therapeutic response
• Peak: Time drug reaches maximum therapeutic response
• Duration: Time drug concentration sufficient for therapeutic response

Therapeutic Drug Monitoring

• Peak level: Highest blood level after new dose
• If too high: toxicity
• Trough level: Lowest blood level right before next dose.
• If too low: not therapeutic

Pharmacodynamics

• Study of what drug does to the body
• Mechanism of drug actions in tissues
• Drug receptor interactions

Ways Drugs Produce Therapeutic Effects

• Modifying rate at which cells or tissues function
• Cannot make cell/tissue perform function not designed for

Pharmacodynamics: Mechanisms of Action

• Receptor interactions
• Enzyme interactions
• Selective interactions
• Nonselective interactions

Receptor Interactions

• Drug binds to receptor for response
• Agonists: enhance/activate response
• Partial agonists: Diminished response when compared to full agonists
• Antagonists: Block response of agonist by binding to site

Table 2-8 Drug-Receptor Interactions (Example of interaction)

• Agonist: Drug binds to receptor, elicits a response
• Partial agonist: Drug binds to receptor, diminishes response compared to full agonist, prevents binding of other drugs
• Antagonist: Drug binds to receptor, no response preventing binding of agonists.
• Competitive antagonist: competes for binding to receptor with agonist
• Non-Competitive antagonist: binds to different receptor site inactivating it.

Pharmacotherapeutics

• Use of drugs and indications for disease prevention and treatment
• Empirical therapeutics
• Preventative
• Rational therapeutics
• Actual treatment

Pharmacotherapeutics: Types of Therapies

• Acute therapy
• Maintenance therapy
• Chronic illness treatment
• Supplemental/replacement therapy
• Palliative therapy (symptom management)
• Supportive therapy
• Prophylactic therapy (prevention of illness)
• Empiric therapy

Contraindications

• Patient characteristics/conditions making drug dangerous
• Assessing for contraindications is important
• Examples include allergies, other medication interactions, organ dysfunction

Monitoring

• Evaluating drug therapy effectiveness
• Clinical response (blood work, subjective/objective data)
• Intended therapeutic action
• Unintended but potential adverse effects

Monitoring (cont'd)

• Therapeutic index
• Ratio of a drug's toxic level relative to therapeutic level
• Tolerance
• Decreasing response to repeated doses
• Dependence (physiological or psychological need)
• Withdrawal (stoppage of drug)
• Interactions (drugs/other drugs/food)
• Additive effects, synergistic effects, antagonistic effects, incompatibility
• Adverse reactions (side effects, hypersensitivity/allergic reactions, idiosyncratic reactions, genetic deficiencies)
• Monitoring and follow up for Toxicity risk
• Close monitoring required for low therapeutic index drugs
• Side effects: predictable, often dose related, resolve after discontinuing medication.

Other Drug-Related Effects

• Teratogenic effects
• Structural defects to the fetus( 3 weeks to 3 months pregnancy suspected)
• Mutagenic effects
• Permanent changes to the genetic code
• Carcinogenic effects
• Cancer-causing effects

Toxicology

• Study of poisons and unwanted responses to drugs/chemicals
• Poisoning
• Overdoses

This quiz will test your understanding of pharmacologic principles in conjunction with pathophysiology. It covers key definitions, drug names, and the mathematical competencies necessary for medication management. Prepare to engage with concepts essential for nursing practice and patient care.