Pharm(unit1)

Introduction to Pharmacology and Medicine Foundations

• Etymology: The term "pharmacology" is derived from two Greek words:     * Pharmakon: Meaning medicine.     * Logos: Meaning study.

• Definition: Pharmacology is the study of drugs and their actions on living organisms.

• Development of Medications: Medications are developed through two primary methods:     * Synthetic Production: Created in a laboratory setting.     * Natural Sources: Derived from plants or minerals.

Drug Naming Conventions

• Chemical Name:     * Represents the scientific name describing the drug's molecular structure.     * There is only one unique chemical name per drug.     * Characteristics: Difficult to pronounce, long, and hard to remember.     * Example: Ethyl $4-(8-\text{chloro-}5,6\text{-dihydro-}11H\text{-benzo}[5,6]\text{cyclohepta}[1,2\text{-}b]\text{pyridin-}11\text{-ylidene})-1\text{-piperidinecarboxylate}$ (the chemical name for Claritin/Loratadine).     * Rare cases where chemical names are used commonly in clinical settings: Calcium gluconate, Sodium chloride.

• Generic Name (Official Name):     * This is the official, non-proprietary name (not owned by a specific company).     * Assigned by the FDA (Food and Drug Administration).     * Characteristics: Usually less complicated and easier to remember than the chemical name, though often harder than the trade name. Written in lowercase.     * Criticality: This name is the standard used for board examinations (NCLEX).     * Examples: Loratadine, Diphenhydramine, Acetaminophen.

• Trade or Brand Name:     * The manufacturer's name selected for marketing purposes.     * It is owned by a specific company and is often short and easy to remember.     * Visual Indicators: Always capitalized on packaging and accompanied by a trademark symbol ($R$ or ${}^{TM}$).     * Examples: Claritin, Benadryl, Tylenol.

• Name Comparison Example:     * Generic: Acetaminophen.     * Trade: Tylenol.     * Generic: Diphenhydramine.     * Trade: Benadryl.

Drug Classification and Legal Categories

• Primary Classification Methods:     * By Use: Organized into classes based on their therapeutic application.     * By Harm Potential: Organized into categories based on potential for misuse.

• Prescription Drugs:     * Requires a prescription from a Health Care Provider (HCP), which includes MDs, NPs, and Dentists.     * Prescription Components: Name of the drug, dosage, route of administration, and electronic signature.     * Electronic Prescription Benefits:         * Preferred over hands-written pads to prevent pharmacist interpretation errors.         * Ensures all data (quantity, route, dose) is included.         * Prevents patients from altering the prescription.         * Allows for monitoring of adverse effects and therapy maximization.

• Over-the-Counter (OTC) Drugs:     * Can be dangerous if the label is not followed or understood.     * Dosage Complexity: For example, Tylenol Extra Strength is 500mg per pill (1000mg per dose of two). One must not exceed 4000mg in a 24hour period to prevent liver damage.     * Patient Education: Patients may not realize different drugs (like Excedrin vs. Tylenol) share ingredients or that some medications (like Ibuprofen) have different dosage jump increments (e.g., 200mg to 400mg).     * Medication Reconciliation: The nurse's job to ask patients exactly what OTC drugs they take at home to identify potential interactions with prescribed medications.

• Controlled Substances:     * High potential for addiction and abuse; strictly monitored by the DEA (Drug Enforcement Administration).     * Physical Dependence: An altered physical state caused by nervous system adaptation to repeated drug use. Cessation leads to physical withdrawals (discomfort).     * Psychological Dependence: A compulsion, craving, or mental desire to use the substance for a pleasurable experience.     * Schedules of Controlled Substances:         * Schedule I: Highest abuse potential; severe dependence risk; no accepted medical use in the US. Examples: Heroin, Ecstasy, Peyote, Cannabis (federally).         * Schedule II: High abuse potential; severe physical/psychological dependence; approved for medical use. Examples: Fentanyl, Methadone, Morphine, Oxycodone, Hydrocodone, Adderall, Ritalin.         * Schedule III: Less abuse potential than Schedule II; moderate-to-low physical/psychological dependence. Examples: Steroids, Testosterone, Ketamine, Synthetic THC, Tylenol with codeine.         * Schedule IV: Lower abuse potential than Schedule III; limited dependence potential. Examples: Benzodiazepines, sedatives, Tramadol.         * Schedule V: Lowest abuse potential. Examples: Small amounts of opioids in cough syrups (antitussives) or antidiarrheals, Lyrica.

Drug Development and FDA Approval Phases

• Pre-FDA Phase (Preclinical Research):     * Occurs before FDA involvement. Extensive laboratory testing performed on animals.

• FDA Clinical Phases (Human Testing):     * Phase 1: Tested on healthy volunteers to assess basic drug effects.     * Phase 2: Tested on individuals with the targeted disease to evaluate effectiveness and monitor for adverse effects.     * Phase 3: Tested on large groups in medical centers to establish safety, dosage ranges, and identify secondary adverse reactions.

• Phase 4: Post-Marketing Surveillance:     * Occurs after the drug is available to the general public.     * Continuous monitoring for adverse reactions; the FDA can pull a drug from the market if safety concerns arise during this phase.

• Special Expedited Programs:     * Orphan Drug Act: For drugs treating rare diseases.     * Accelerated Approval: For urgent medical needs (e.g., COVID-19 vaccines, HIV/AIDS treatments).     * REMS Program: Extra safety requirements for high-risk drugs.

Phases of Drug Action in the Body

• 1. Pharmaceutic Phase (Dissolving):     * Only applies to oral drugs.     * Fastest Absorption: Liquids and parenteral (injected) drugs are already dissolved.     * Slower Absorption: Tablets and capsules must break down in the GI tract.     * Enteric-Coated/Extended Release: These do not dissolve in the stomach; they dissolve in the small intestine to delay drug release.

• 2. Pharmacokinetics (Movement):     * Absorption: How the drug enters the bloodstream.         * Active Transport: Uses energy to move from low to high concentration.         * Passive Transport: No energy; moves from high to low concentration.         * Pinocytosis: The cell engulfs the drug (the "Pac-Man" effect).         * Factors: Route (IV is fastest), solubility (lipid-soluble crosses membranes easier than water-soluble), and tissue condition.     * First-Pass Effect: Oral drugs absorbed in the small intestine travel to the liver via the portal system. The liver filters some of the drug before it reaches circulation, effectively reducing drug strength.     * Distribution: How the drug spreads. High blood-flow organs (heart, liver, kidneys) receive drugs fastest. Skin and muscles are slower.     * Metabolism (Biotransformation): How the body breaks down the drug. The Liver is the primary organ. Others include kidneys, lungs, and intestinal lining.     * Excretion: Removal of waste. Primary organ: Kidneys. Other routes: Sweat, breast milk, feces, breath.     * Half-Life: The duration of time required for $50\%$ of the drug to be eliminated from the body.         * Short half-life = More frequent dosing.         * Long half-life = Less frequent dosing.     * Clocking Action:         * Onset: When the drug starts to work.         * Peak: When the drug has its strongest effect.         * Duration: How long the drug continues to work.

• 3. Pharmacodynamics (Effect):     * The study of how the drug works in the body and its clinical effects. Drugs target specific "target sites" (organs or tissues) to change cell function or environment.

Considerations for Specific Populations

• Pregnancy and Lactation:     * General Rule: Avoid all drugs unless the benefit outweighs the risk. No drugs (including herbals) should be taken without HCP approval.     * Teratogenic Effects: Most dangerous in the first trimester when heart and neural tube development occur.     * Labeling Change (2015): The FDA replaced the old $A$, $B$, $C$, $D$, $X$ letter system with detailed summaries: Risk Summary, Clinical Considerations, and Supporting Data.     * Historical Categories:         * A: Safe; human studies show no risk.         * B: Likely safe; animal studies safe, but human data lacking.         * C: Risk possible; evidence of harm in animals.         * D: Known risk to fetus; used only if life-saving.         * X: Not safe; clear harm shown; contraindicated.     * Lactation: Use the LactMed database to check drug safety for breastfeeding mothers.

• Geriatrics and Pediatrics:     * These populations often require lower doses due to immature (children) or declining (elderly) kidney and liver function, which slows excretion and increases toxicity risk.

Drug Reactions and Safety

• Adverse Reactions: Undesirable drug effects ranging from mild (nausea, drowsiness) to life-threatening.

• Allergic Reaction (Hypersensitivity): An immune system response.

• Anaphylactic Shock: A severe, multi-systemic medical emergency requiring Epinephrine.     * Symptoms:         * Respiratory: Bronchospasm, dyspnea, throat fullness, wheezing.         * CV: Extremely low BP (hypotension), high heart rate (tachycardia), palpitations.         * Integumentary: Hives, itching, angioedema (swelling under skin of lips, mouth, and throat — an airway risk).         * GI: Nausea, vomiting, diarrhea ($N/V/D$).

• Drug Idiosyncrasy: An unusual or opposite response to a drug (e.g., a sedative making a patient wakeful).

• Drug Tolerance: A decreased response to a drug requiring a higher dose for the same effect (common with opioids).

• Cumulative Effect: Occurs when the body cannot break down or excrete a drug before the next dose, leading to toxicity.

• Drug-Drug Interactions:     * Additive ($1 + 1 = 2$): Two drugs with similar effects combined (e.g., Alcohol and Heparin increasing bleed risk).     * Synergistic ($1 + 1 = 3$): Two drugs combined create a disproportionately large or fatal effect (e.g., Alcohol and Hypnotics).     * Antagonistic ($1 - 1 = 0$): Drugs cancel each other out (e.g., giving Protamine as an antidote to neutralize Heparin).

• Drug-Food Interactions: Grapefruit juice is widely contraindicated. Tetracycline cannot be taken with dairy (calcium) as it decreases absorption.

Herbal and Complementary Medicine

• Regulations: Herbals, vitamins, and supplements are not regulated by the FDA under the Dietary Supplement Health and Education Act ($1994$). They lack standardization in purity and potency.

• Safety: "Natural" does not mean safe. Herbals must be stopped before surgery to prevent interactions.

• CAM Therapy:     * Complementary: Used alongside traditional medicine (e.g., aromatherapy, massage).     * Alternative: Used instead of traditional medicine.

Medication Administration (Chapter 2)

• The Six Rights of Medication Administration:     1. Right Client (Name and Date of Birth).     2. Right Drug.     3. Right Dose (0.5mg is correct; never use trailing zeros like 5.0mg).     4. Right Route.     5. Right Time.     6. Right Documentation.

• Types of Orders:     * Standing Order: Preapproved; used for common conditions when the doctor is unavailable.     * Single Order: Given once at a specific time.     * PRN Order: Administered as needed based on specific patient criteria.     * STAT Order: Given immediately.

• Medication Errors: Most common causes are distractions and calculation errors. Nurses must always check allergies and Verify patient identifiers before every administration.