Pharmacology Lecture: Adverse Drug Reactions & Interactions

Administrative & Course Logistics

• In-class activity submission link
  • Always located in the course Module area.
• ATI (Assessment Technologies Institute) access
  • Instructor verified that (almost) everyone now has access.
  • Students confirmed ATI content clarified lecture topics.
• Key upcoming deadlines
  • Introduction to Pharmacology module test due 11-th at 11:59 p.m.
  • All current ATI module exams & submissions due by Friday 23:59 (except Safe-Medication module—see below).
  • Safe Medication Administration module exam must be finished by Sunday 23:59 so its content can be used for Monday review.
• Exam schedule
  • First pharmacology exam covers material from Day 1 (yesterday), Day 2 (today) & Day 3 (Monday).
  • Exam date: next Tuesday (exact time TBA); multiple-choice format, possible “select-all-that-apply,” no True/False.
• Optional study hall
  • Monday, 1 – 2 p.m. in classroom; will include a pharmacology “Bingo” review game.
• Additional ATI resources
  • In ATI dashboard → My ATI → Review Modules 2023 RN → eBooks
  • Accessible PDFs for Fundamentals, Leadership, Pharmacology, etc.
• File-upload tips
  • LMS allows multiple attachments (e.g., front & back of worksheets).
  • Organizational advice: keep personal calendar, track deadlines, time-management = professionalism.

Warm-Up & Review: Kahoot Game

• Purpose: 7-question, non-graded review of prior lecture.
• 1st, 2nd, 3rd place received small prizes (suckers, miscellaneous gifts).
• Representative questions & correct responses
  • “Where are most drugs metabolized?” → Liver.
  • “Which route is parenteral?” (choose all) → IV, IM, sub-Q, etc.
  • Reinforced concepts of excretion (kidneys) & drug classifications.
• Class observations
  • No laptop notes taken during game; instructor teased “boring ones.”
  • Students enthusiastic; affirmed comprehension gaps for later focus.

Expected Pharmacological Action vs Therapeutic Use

• Expected pharmacological action
  • The direct mechanism of action a drug exerts in the body (cellular/biochemical effect).
  • Physicians select drugs based on this action.
  • Example: Antibiotics disrupt bacterial cell wall replication → kill or inhibit microbes.
• Therapeutic use
  • The clinical reason the drug is prescribed; desired patient outcome.
  • Drugs often have multiple therapeutic uses:
  • Ibuprofen: antipyretic and anti-inflammatory/analgesic.
  • Diphenhydramine (Benadryl): allergy relief and motion-sickness prophylaxis.

Side Effects vs Adverse Drug Reactions (ADR)

• Side effect (secondary effect)
  • Predictable, often dose-dependent, sometimes tolerable or self-limiting.
  • Eg: Benadryl → drowsiness & dry mouth; GI upset from many PO meds.
• Adverse drug reaction (ADR)
  • Unintended, undesired, potentially harmful outcomes when drug given correctly.
  • Range: mild rash → severe anaphylaxis.

Primary vs Secondary Adverse Actions

• Primary (overdose) action
  • Excess drug concentration → exaggerated pharmacology.
  • Examples:
  • \text{Warfarin} overdose → uncontrolled bleeding.
  • Excess antihypertensive → hypotension, syncope.
• Secondary adverse action
  • Diverse effects beyond desired action, unrelated to dose.
  • Example: Antihistamines ↓ secretions & depress CNS → sedation.

Common ADRs by Body System

• Central Nervous System (CNS): agitation, confusion, psychosis, seizures, coma, respiratory depression.
• Gastrointestinal (GI): N/V, diarrhea/constipation, ulceration, GI bleed.
• Hematologic: bone-marrow suppression, anemia, excessive clotting or bleeding.
• Hepatotoxicity / Nephrotoxicity: impaired metabolism or excretion → drug accumulation.
• Hypersensitivity / Allergy
  • IgE-mediated response to prior exposure; may progress to anaphylaxis
  • S/S: facial/lip edema, throat tightness, wheeze, \uparrow HR, \downarrow BP; can be fatal.
  • Example narrative: Instructor developed new amoxicillin rash → escalating reaction → required antihistamines & carries EpiPen.

Electrolyte, Glucose & Teratogenic Effects

• Potassium imbalance
  • Hypo/Hyper-kalemia → cardiac dysrhythmias.
• Glucose dysregulation
  • Some drugs ↓ serum glucose; others ↑ by stimulating glycogenolysis.
• Teratogenicity
  • Drugs crossing placenta causing fetal malformations, especially in 1st trimester.
  • Categorized A\rightarrow X (FDA).
  • A = controlled studies show no risk; X = contraindicated in pregnancy.

Tolerance, Cumulative Effect & Toxicity

• Tolerance: ↓ physiologic response over time → need ↑ dose or change agent.
• Cumulative effect
  • Impaired metabolism/excretion (e.g., renal/hepatic insufficiency) → incremental build-up.
  • Leads to toxicity if not monitored.
• Toxicity
  • Harmful drug levels; may be irreversible.
  • Example: Vancomycin ototoxicity (cranial nerve VIII damage) → monitor peak & trough levels.

Precautions vs Contraindications

• Precaution: Drug may be given but requires close monitoring.
  • Eg: Anticoagulant in pt with bleeding ulcer (benefit vs risk).
  • Populations: elderly, pregnant, breastfeeding, immunocompromised.
• Contraindication: Absolute “do NOT give.”
  • Pediatric pt receiving adult dose; known penicillin allergy; known dangerous drug-drug interaction.

Drug–Drug Interactions (DDIs)

• Possible outcomes: ↓ effect, ↑ effect, or new adverse effect.
• Pharmacodynamic relationships
  • Antagonist: One drug blocks receptor/action of another (e.g., β-agonist bronchodilator + β-blocker).
  • Additive: Similar mechanisms → combined effect = sum (EtOH + sedative).
  • Synergistic: Different mechanisms → combined effect > sum (Pepcid + Prevacid for GERD; ASA + warfarin ↑ anticoagulation).
  • Agonist: Drug mimics endogenous ligand & stimulates receptor (serotonin agonists).

Food–Drug Interactions

• Mechanisms
  1. ↑ Drug activity: Food enhances absorption or slows metabolism.
  • Iron + Vitamin C (orange juice) ↑ absorption.
  • Grapefruit inhibits CYP450 → ↑ serum levels of some Ca-channel blockers.
  1. ↓ Drug activity: Food binds drug or opposes its action.
  • Spinach (vit K) antagonizes warfarin.
  • High-fiber diet ↓ digoxin absorption.
  1. Toxic/Adverse combo
  • Acetaminophen + alcohol → hepatotoxicity.
  • MAO-Is + tyramine foods → hypertensive crisis.

Drug Therapy Across the Lifespan

• Infants/Children
  • Immature liver/kidney; altered gastric pH; larger body-water %.
  • Doses based on age, weight, body-surface-area.
• Elderly
  • ↓ renal/hepatic function, ↓ GI motility, ↑ gastric pH, ↓ cardiac output.
  • Prone to ADRs, dosing adjusted; vigilant lab monitoring.
• Pregnancy
  • Placental transfer—many drugs cross barrier.
  • Category-based risk assessment (A-X).
  • Some drugs deferred until 2ᵈ/3ʳᵈ trimester.
• Breastfeeding
  • Drugs can appear in milk; e.g., Benadryl decreases milk supply so discouraged postpartum.

Polypharmacy in Older Adults (Question 20 Context)

• Multiple chronic illnesses → \ge 5 concurrent prescriptions common.
• Risks
  • Confusion over schedules → missed or doubled doses.
  • ↑ probability of DDIs & cumulative toxicity.
  • Sensory/DEXTERITY issues (opening bottles, reading labels).
  • Cognitive decline affects adherence.
• Nursing interventions: Medication reconciliation, pill organizers, simplified regimens, family/caregiver teaching.

Nursing Role: Client Education & Evaluation

• Begin education at admission & continue.
• Teach
  • Drug name(s) – generic & brand.
  • Purpose & mechanism.
  • Dose, route, timing (with/without food; diurnal variation).
  • Expected benefits & common side effects.
  • Serious ADRs: when to call provider/911.
  • Food, alcohol, OTC & herbal interactions.
• Assess learner variables
  • Literacy, language, cognition, learning style (visual/audio/kinesthetic).
  • Provide written materials, pictograms, demonstrations.
• Return demonstration / Teach-back to verify comprehension (e.g., insulin self-injection technique).
• Document teaching & patient response.

Classroom Plans & Miscellany

• Later collect handwritten answer to Question 20 (why elders on many meds at higher ADR risk).
• Instructor reminder: “Tell me if I talk too fast.”
• Microphone feedback resolved during lecture.
• Encouragement: Use ATI + lecture slides; entire content fair game although test cannot cover everything.
• Future interactive tools: Bingo review to make study session engaging.

Ethical & Practical Implications

• Providers must weigh benefit vs risk (e.g., teratogenic drugs, anticoagulants with ulcers).
• Nurses serve as last safety check; must understand pharmacology, monitor labs, advocate for dosage adjustments.
• Patient autonomy: informed consent hinges on clear, culturally appropriate education.