Pharmacology: A Complete Guide for Nursing Students

 

Introduction:

Pharmacology is the cornerstone of safe and effective nursing care. It involves the study of drugs, their sources, properties, actions, and effects on living organisms. As a nursing student, mastering pharmacology not only sharpens clinical judgment but also improves patient outcomes by ensuring proper medication administration and monitoring.

This article provides an in-depth yet student-friendly guide to pharmacology, including drug classifications, mechanisms, uses, side effects, and nursing implications—ideal for NCLEX preparation and clinical rotations.

What is Pharmacology?

Pharmacology is the branch of biomedical science that deals with the study of drugs and their effects on the human body. It involves understanding how medications work, how they're metabolized, and how they interact with body systems and other drugs.

Branches of Pharmacology:

Clinical Pharmacology:

Focuses on the effects and use of drugs in humans.

Pharmacokinetics:

Describes how the body absorbs, distributes, metabolizes, and excretes drugs (ADME).

Pharmacodynamics:

Explains how drugs act on the body, including mechanisms of action and dose-response relationships.

Toxicology:

Study of harmful effects of drugs and chemicals.

Drug Classifications:

Drugs are categorized based on their therapeutic use or chemical characteristics. Here are key classifications:

Drug Class	Example	Use
Analgesics	Paracetamol, Morphine	Pain relief
Antibiotics	Amoxicillin, Azithromycin	Bacterial infections
Antihypertensives	Amlodipine, Enalapril	High blood pressure
Antidiabetics	Metformin, Insulin	Diabetes management
Antipsychotics	Haloperidol, Risperidone	Schizophrenia, psychosis
Diuretics	Furosemide, Spironolactone	Edema, hypertension
Anticoagulants	Warfarin, Heparin	Prevent blood clots
Anticonvulsants	Phenytoin, Valproate	Seizures

Pharmacokinetics (ADME):

Absorption:

How the drug enters the bloodstream.
💊 Example: Oral drugs absorb in the GI tract.

Distribution:

How the drug spreads through body fluids and tissues.

Metabolism:

Liver primarily breaks down the drug into active/inactive forms.

Excretion:

Kidneys usually eliminate the drug through urine.

Pharmacodynamics:

Understanding the mechanism of action is crucial.

• Agonists: Bind to receptors and activate them (e.g., Morphine).

• Antagonists: Block receptors without activating them (e.g., Naloxone).

• Therapeutic Index (TI): Narrow TI drugs like Digoxin require close monitoring.

Drug Routes of Administration:

Route	Example	Advantage
Oral	Tablets, Capsules	Convenient, non-invasive
Intravenous	IV injections	Fastest action, emergency use
Intramuscular	Vaccines	Moderate absorption
Subcutaneous	Insulin	Slow, sustained absorption
Topical	Creams, ointments	Localized effect

Factors Affecting Drug Action:

• Age (neonates & elderly need dose adjustments)

• Weight and body surface area

• Renal and liver function

• Genetics and allergies

• Drug interactions

Adverse Drug Reactions (ADRs):

• Mild: Rash, nausea, dizziness

• Severe: Anaphylaxis, Stevens-Johnson Syndrome

• Nurses must monitor, document, and report any ADRs promptly.

Nursing Responsibilities in Pharmacology:

Before Administering Medication:

✅ Check patient’s identity
✅ Review drug order
✅ Check for allergies
✅ Verify dose, time, and route
✅ Review drug interactions and contraindications

During Administration:

✅ Use aseptic technique
✅ Ensure proper route and technique
✅ Monitor for immediate reactions

After Administration:

✅ Document time, dose, and effects
✅ Monitor for side effects or adverse reactions
✅ Educate patient on drug purpose and precautions

Commonly Used Drugs and Nursing Considerations:

1. Paracetamol (Acetaminophen)

• Use: Pain and fever

• Action: Inhibits prostaglandin synthesis

• Nursing Tip: Monitor liver function in chronic use.

2. Aspirin

• Use: Pain, inflammation, clot prevention

• Action: Inhibits COX enzyme

• Contraindication: GI ulcers, bleeding disorders

• Nursing Tip: Give with food to reduce GI upset.

3. Insulin

• Use: Diabetes

• Types: Rapid-acting, Short-acting, Long-acting

• Nursing Tip: Check blood glucose before giving.

4. Furosemide (Lasix)

• Use: Edema, hypertension

• Action: Loop diuretic

• Nursing Tip: Monitor electrolytes (especially potassium) and BP.

5. Enalapril

• Use: Hypertension, heart failure

• Action: ACE inhibitor

• Nursing Tip: Monitor for cough, hyperkalemia, BP.

High-Alert Medications:

These drugs require double-checking and extra caution due to high risk:

• Insulin

• Heparin

• Chemotherapy drugs

• Potassium chloride (IV)

Drug Storage Guidelines:

• Refrigerated if required (e.g., insulin)

• Away from sunlight and moisture

• Proper labeling with expiry date

• Secure location for controlled substances

Drug Calculations in Nursing:

Common Formulas:

• Dosage = (Desired Dose / Stock Dose) × Volume

• IV Flow Rate (gtt/min) = (Volume × Drop Factor) / Time (min)

💡 Always double-check calculations, especially in pediatrics and geriatrics.

Nursing Pharmacology Mnemonics:

Mnemonic	Use
SLUDGE	Cholinergic effects
ABCD	Anticholinergic side effects
PINCH	High-alert medications
ROME	Respiratory/Metabolic acidosis/alkalosis

Pharmacology for NCLEX & Nursing Exams:

• Focus on drug classifications not just individual names.

• Understand side effects, nursing considerations, and contraindications.

• Prioritize patient safety and education.

• Practice medication calculation questions regularly.

Bonus Tip for Nursing Students:

Create flashcards, use apps like Medscape or Epocrates, and join study groups to reinforce learning. Don't memorize—understand the mechanism and think critically about why and how each drug is used.