Pharmacology Study Guide
Master drug classifications, mechanisms of action, therapeutic uses, adverse effects, and essential nursing considerations for NCLEX success.
Introduction to Pharmacology
Pharmacology is the study of drugs and their effects on living systems. For nursing, understanding pharmacology is essential for safe medication administration, patient education, and recognizing adverse effects. This guide covers major drug classifications organized by therapeutic use and body system.
Pharmacokinetics and Pharmacodynamics
Pharmacokinetics (What the body does to the drug)
- Absorption: Drug enters the body through GI tract, IV, IM, topical, or inhalation routes. Rate depends on route, pH, food interactions, and drug properties.
- Distribution: Drug travels through blood to tissues. Factors include plasma protein binding, lipid solubility, and blood-brain barrier penetration.
- Metabolism: Liver primarily metabolizes drugs through Phase I (modification), Phase II (conjugation), and Phase III (transport) reactions. Creates active or inactive metabolites.
- Elimination: Kidneys excrete unchanged drugs and metabolites (glomerular filtration, tubular secretion, reabsorption). Also via bile, lungs, skin.
- Half-life (t½): Time for plasma concentration to decrease 50%. Used to determine dosing intervals and steady-state achievement.
Pharmacodynamics (What the drug does to the body)
- Agonist: Binds to receptor and activates it, producing a response.
- Antagonist: Binds to receptor but doesn't activate it, blocking agonist effects.
- Partial Agonist: Produces less than maximal response, even at high concentrations.
- Potency: Amount of drug needed to produce 50% of maximal effect (lower dose = higher potency).
- Efficacy: Maximal response a drug can achieve regardless of dose.
- Receptor: Cellular target where drugs bind, typically proteins on cell surface or inside cells.
Cardiovascular Medications
ACE Inhibitors (lisinopril, enalapril)
Mechanism: Block angiotensin-converting enzyme, reducing angiotensin II formation and aldosterone secretion.
Uses: Hypertension, heart failure, post-MI, diabetic nephropathy.
Adverse Effects: Persistent dry cough (ACE-inhibitor induced), hyperkalemia, acute kidney injury, angioedema (serious).
Nursing Considerations: Monitor K+ and creatinine. Teach to take at bedtime. ACE inhibitors are teratogenic—assess pregnancy status. Cough resolves when stopped.
Beta-Blockers (metoprolol, atenolol, propranolol)
Mechanism: Block beta-adrenergic receptors, reducing heart rate, contractility, and cardiac output.
Uses: Hypertension, angina, arrhythmias, heart failure, migraine prophylaxis, hyperthyroidism.
Adverse Effects: Bradycardia, hypotension, fatigue, sexual dysfunction, bronchospasm (in asthmatics), hypoglycemia masking in diabetics.
Nursing Considerations: Monitor heart rate and BP. Don't stop abruptly (rebound hypertension). Warn diabetics about masked hypoglycemia. Hold if HR <60 or SBP <90.
Diuretics
Loop Diuretics (furosemide, bumetanide): Act on ascending loop of Henle. Potent diuretics for acute edema and pulmonary edema. Cause significant K+ and Mg+ wasting.
Thiazides (hydrochlorothiazide): First-line for hypertension. Mild diuretic effect. Can cause hyperglycemia, hyperuricemia, sexual dysfunction.
Potassium-sparing (spironolactone, amiloride): Retain K+. Use in heart failure with ACE inhibitors.
Nursing Considerations: Monitor I&Os, weight daily, K+, Na+, Mg2+. Assess for dehydration and hypotension. Give loop diuretics in AM to avoid nocturia.
Nitroglycerin and Vasodilators
Nitroglycerin: Vasodilator for angina. Rapid sublingual onset (5-15 min). Causes tolerance with continuous use—schedule nitrate-free intervals.
Calcium Channel Blockers (diltiazem, verapamil): Reduce coronary vasospasm and cardiac contractility. Use in angina and arrhythmias. Side effects: constipation, reflex tachycardia.
Nursing Considerations: NTG headaches indicate effectiveness. Store in cool, dark place. If chest pain not relieved after 3 doses 5 minutes apart, call 911. Monitor BP for hypotension.
Anticoagulants and Antiplatelets
Warfarin (Coumarin): Vitamin K antagonist. Narrow therapeutic window. Requires INR monitoring. Many drug/food interactions.
DOACs (apixaban, rivaroxaban): Direct oral anticoagulants. Predictable pharmacokinetics, no monitoring needed, but irreversible.
Heparin: IV or SQ. Rapid onset, short duration. Requires PTT monitoring. Risk of HIT (heparin-induced thrombocytopenia).
Aspirin: Antiplatelet for MI prevention. Irreversible platelet inhibition. GI upset common.
Nursing Considerations: Assess for bleeding signs. Teach INR importance with warfarin. Use soft toothbrush. Report hematuria, easy bruising. Check Hgb/Hct.
Respiratory Medications
Bronchodilators
Beta-2 Agonists (albuterol, salmeterol): Rapid relief of bronchoconstriction. Short-acting (2-6 hours) for acute symptoms; long-acting (12 hours) for maintenance. Side effects: tremor, tachycardia, nervousness.
Anticholinergics (ipratropium): Prevent acetylcholine-induced bronchoconstriction. Used with beta-agonists for synergistic effect. Slower onset than beta-agonists.
Nursing Considerations: Teach proper inhaler technique. Use spacer for better delivery. Rinse mouth after inhalation to prevent thrush. Monitor HR and BP. Provide rest between puffs.
Inhaled Corticosteroids
Mechanism: Reduce inflammation, airway edema, and mucus production. Prevent asthma exacerbations. Not effective for acute bronchospasm.
Examples: Fluticasone, beclomethasone, budesonide.
Side Effects: Oral thrush (local effect), hoarseness, dysphonia. Systemic effects minimal with inhalation route.
Nursing Considerations: Rinse mouth thoroughly after use to prevent thrush. These are maintenance medications, not rescue drugs. Takes days-weeks for full benefit. Use proper inhaler technique.
Mucolytics and Expectorants
Acetylcysteine (Mucomyst): Breaks disulfide bonds in mucus, reducing viscosity. Aerosolized for inhalation.
Guaifenesin (Robitussin): Expectorant that thins secretions. Helps patient expectorate. OTC available.
Nursing Considerations: Encourage hydration—increases effectiveness. Nebulized medications can cause bronchospasm in sensitive patients. Position for optimal drainage. Monitor cough effectiveness.
Endocrine Medications
Insulin Types
Rapid-acting (lispro, aspart): Onset 5-15 min, peak 1-2 hours. Used with meals for glycemic control.
Short-acting/Regular (crystalline): Onset 30 min-1 hour, peak 2-4 hours, duration 6-8 hours. Given 15-30 min before meals.
Intermediate (NPH): Onset 1-2 hours, peak 4-12 hours. Provides basal insulin. Often combined with short-acting.
Long-acting (glargine, detemir): Onset 2-4 hours, minimal peak, lasts 24+ hours. Basal coverage once or twice daily.
Nursing Considerations: Always verify insulin type before giving. Inject at bedtime for absorption. Rotate injection sites. Never mix long-acting insulins. Teach patient signs of hypoglycemia and hyperglycemia.
Oral Hypoglycemics
Metformin: First-line for Type 2 DM. Reduces hepatic glucose production. Monitor renal function—hold if Cr > 1.5. Risk of lactic acidosis (rare).
Sulfonylureas (glyburide, glipizide): Stimulate insulin secretion. Can cause hypoglycemia. Avoid in renal/hepatic dysfunction.
DPP-4 Inhibitors (sitagliptin): Prolong incretin activity. Weight neutral. GI upset possible.
GLP-1 Agonists (semaglutide): Increase insulin secretion and reduce appetite. Weight loss benefit. Some risk of pancreatitis.
Nursing Considerations: Teach foot care, eye exams, and medication adherence. Monitor HbA1c. Report nausea, vomiting, abdominal pain (pancreatitis risk with GLP-1). Assess blood glucose regularly.
Thyroid Medications
Levothyroxine (Synthroid): T4 replacement for hypothyroidism. Long half-life allows once-daily dosing. Take on empty stomach for best absorption.
Propylthiouracil (PTU) and Methimazole: Reduce thyroid hormone synthesis in hyperthyroidism. PTU has lower agranulocytosis risk. Monitor CBC.
Iodine (Lugol's solution): Inhibits hormone release. Used acutely in thyroid storm. Unpleasant taste.
Nursing Considerations: Check TSH 6-8 weeks after levothyroxine start/dose change. Take on empty stomach. Monitor for signs of hypo/hyperthyroidism. PT/INR may be affected by thyroid medications if on anticoagulants.
Neurological Medications
Antiepileptics
Phenytoin (Dilantin): Classic antiepileptic. Narrow therapeutic window (10-20 mcg/mL). Many drug interactions. Gingival hyperplasia and hirsutism side effects.
Valproic Acid (Depakote): Broad-spectrum antiepileptic. Teratogenic (neural tube defects). Monitor LFTs. Causes tremor, alopecia.
Levetiracetam (Keppra): No drug interactions. Well-tolerated. Behavioral changes, dizziness possible.
Benzodiazepines (lorazepam, diazepam): Acute seizure management, status epilepticus. Risk of dependence with chronic use. CNS depression.
Nursing Considerations: Verify seizure type before prescribing. Never abruptly stop—risk of rebound seizures. Teach safety (wear medic alert, avoid water activities). Monitor therapeutic levels. Assess for toxicity signs.
Parkinson's Medications
Levodopa/Carbidopa (Sinemet): Levodopa is converted to dopamine. Carbidopa prevents peripheral conversion, increasing CNS availability. Involuntary movements (dyskinesia) develop long-term.
Dopamine Agonists (bromocriptine, pramipexole): Directly stimulate dopamine receptors. Effective but cause hallucinations, orthostatic hypotension.
MAO-B Inhibitors (selegiline): Inhibit dopamine breakdown. Extend levodopa efficacy. Dietary restrictions (no tyramine) prevent hypertensive crisis.
Nursing Considerations: Take levodopa on empty stomach (protein interferes with absorption). Don't take with high-protein meals. Monitor for "on-off" fluctuations. Report unusual thoughts, hallucinations. Assess fall risk—orthostatic hypotension common.
Antidepressants
SSRIs (sertraline, fluoxetine, paroxetine): Selective serotonin reuptake inhibitors. First-line for depression and anxiety. Takes 2-4 weeks for effect. Sexual dysfunction, weight gain common.
SNRIs (venlafaxine, duloxetine): Inhibit serotonin AND norepinephrine reuptake. Effective for depression and chronic pain. Withdrawal syndrome if stopped abruptly.
Tricyclic Antidepressants (amitriptyline, nortriptyline): Older class. Anticholinergic side effects: dry mouth, urinary retention, constipation, tachycardia. Cardiac effects in overdose. Still used for chronic pain.
Nursing Considerations: Teach patience—antidepressants take weeks to work. Monitor for suicidal ideation (especially first 2 weeks). Taper gradually when discontinuing. Monitor Na+ (SIADH risk). Avoid sudden position changes.
Gastrointestinal Medications
Acid-Reducing Agents
Proton Pump Inhibitors (omeprazole, lansoprazole): Most potent acid reduction. Inhibit H+/K+ pump. Reduces absorption of Ca2+, B12, Fe (long-term use). Increased infection risk (no acid to kill bacteria).
H2-Blockers (famotidine, ranitidine): Moderate acid reduction. Histamine-2 receptor antagonists. Drug interactions. Elderly patients may develop confusion.
Antacids (calcium carbonate, aluminum hydroxide): Neutralize acid. Fast-acting but short duration. Aluminum causes constipation; magnesium causes diarrhea.
Nursing Considerations: Take PPIs 30-60 min before first meal for best effect. H2-blockers can take at bedtime. Space antacids away from other medications. Monitor B12 levels with long-term PPI use. Educate on lifestyle modifications (diet, stress, sleep).
Antimotility and Antidiarrheal Agents
Loperamide (Imodium): Reduces intestinal motility. Over-the-counter. Avoid in inflammatory diarrhea (risk of toxic megacolon).
Bismuth Subsalicylate (Pepto-Bismol): Reduces inflammation and secretion. Dark stools, tongue discoloration. Avoid in salicylate sensitivity.
Octreotide: Somatostatin analog. Reduces GI secretions and motility. Used in variceal bleeding, carcinoid syndrome.
Nursing Considerations: Never use antimotility agents in acute inflammatory bowel disease. Assess for dehydration with diarrhea. Monitor electrolytes (hypokalemia risk). Teach rehydration strategies.
Laxatives and Stool Softeners
Fiber Supplements (psyllium, methylcellulose): Increase stool bulk. Require adequate hydration. Safest long-term option.
Osmotic Laxatives (polyethylene glycol, lactulose): Increase water in stool. Osmotic effect draws water into bowel. Effective for constipation.
Stimulant Laxatives (senna, bisacodyl): Stimulate peristalsis. Fast-acting. Risk of dependence with chronic use.
Stool Softeners (docusate): Reduce stool hardness. Works in 1-3 days. Good for post-surgical constipation prevention.
Nursing Considerations: Assess bowel function before giving laxatives. Emphasize dietary fiber and fluids first. Monitor for fluid/electrolyte losses. Avoid stimulants in acute abdomen. Educate on toilet schedule and privacy.
Essential Pharmacology Study Tips
- • Master drug naming conventions: suffixes reveal drug class (e.g., -statin for statins, -olol for beta-blockers, -pril for ACE inhibitors)
- • Organize by mechanism of action and therapeutic use, not just alphabetically
- • Understand the drug-disease relationship: why is this drug used for this condition?
- • Always know the most common side effects and nursing interventions for each drug class
- • Review pharmacokinetics: absorption, distribution, metabolism, elimination for each drug
- • Study drug interactions: what drugs should NOT be given together and why
- • Memorize therapeutic ranges and when to hold medications (HR <60 for beta-blockers, etc.)
- • Practice patient education points for major drug classes (timing, side effects, warnings)
- • Connect pharmacology to pathophysiology: understand the condition the drug treats
- • Use mnemonics and flashcards to memorize drug classes and their effects