Respiratory Pharmacology for Nursing Students: Drug Classes, Mechanisms, Uses & Side Effects

💊 Nursing Pharmacology Study Guide

Respiratory
Pharmacology

Understand respiratory drugs using a simple approach: classification → target site → mechanism of action → therapeutic effect → adverse effects → nursing considerations.

Start Learning ↓

Respiratory drugs act on receptors, smooth muscle, inflammatory pathways, mucus and airway blood vessels.

🫁 Anatomy 🎯 Targets 💊 Classification 💨 Bronchodilators 🔥 Steroids 🧪 Other Drugs 📚 Summary ✅ Quiz

01 · Basic Foundation

Basic Anatomy of the Respiratory System

Before studying respiratory drugs, understand the structures through which air passes and where respiratory medicines exert their effects.

Nose → Pharynx → Larynx → Trachea → Bronchi → Bronchioles → Alveoli

1

Conducting Airways

The nose, pharynx, larynx, trachea, bronchi and bronchioles conduct air towards the lungs.

2

Bronchial Smooth Muscle

Smooth muscle surrounds the airways. Contraction narrows the airway while relaxation produces bronchodilation.

3

Alveoli

Alveoli are microscopic air sacs where oxygen and carbon dioxide are exchanged between air and pulmonary capillary blood.

02 · Pharmacological Targets

Know These Receptors First

Understanding the receptor makes it much easier to understand how the drug works.

β₂

Beta₂ Receptors

Located predominantly on bronchial smooth muscle.

Stimulation causes: Bronchial smooth-muscle relaxation and bronchodilation.

M₃

Muscarinic M₃ Receptors

Present on airway smooth muscle and airway glands.

Activation causes: Bronchoconstriction and increased airway secretions.

GR

Glucocorticoid Receptors

Located inside inflammatory and other responsive cells.

Activation causes: Suppression of inflammatory pathways.

03 · Classification

Major Classes of Respiratory Drugs

💨

Bronchodilators

Beta₂ agonists, antimuscarinics and methylxanthines.

🔥

Anti-inflammatory

Corticosteroids and selected targeted anti-inflammatory drugs.

💧

Secretion Modifiers

Mucolytics and expectorants.

🤧

Upper Airway Drugs

Antihistamines and nasal decongestants.

04 · Bronchodilators

Drugs That Open the Airways

Bronchodilators reduce airway resistance primarily by relaxing bronchial smooth muscle.

💨

Beta₂-Adrenergic Agonists

Salbutamol · Terbutaline · Formoterol · Salmeterol

+

Salbutamol Terbutaline Formoterol Salmeterol

📍 Target Site Beta₂-adrenergic receptors located mainly on bronchial smooth muscle.

⚙️ Mechanism of Action Beta₂ receptor stimulation activates adenylate cyclase and increases intracellular cAMP, resulting in smooth-muscle relaxation.

β₂ stimulation → Adenylate cyclase ↑ → cAMP ↑ → Smooth muscle relaxes → Bronchodilation

⚠️ Adverse Effects Tremor, palpitations, tachycardia, headache, nervousness, muscle cramps and hypokalaemia, particularly with greater systemic exposure.

🩺 Nursing Considerations Assess respiratory rate, respiratory effort, breath sounds and response to therapy. Monitor pulse and teach correct inhaler technique.

🧠 Exam Point Salbutamol → β₂ receptor → ↑ cAMP → bronchial smooth muscle relaxation → bronchodilation.

🚫

Antimuscarinic Bronchodilators

Ipratropium · Tiotropium · Glycopyrronium

+

Ipratropium Tiotropium Glycopyrronium

📍 Target Site Muscarinic receptors, especially M₃ receptors on airway smooth muscle.

⚙️ Mechanism of Action Block acetylcholine at muscarinic receptors, reducing parasympathetic-mediated bronchial smooth-muscle contraction.

M₃ receptor blocked → Acetylcholine action ↓ → Bronchoconstriction ↓ → Bronchodilation

⚠️ Adverse Effects Dry mouth, throat irritation, unpleasant taste, blurred vision if aerosol reaches the eyes, and urinary retention in susceptible patients.

🩺 Nursing Considerations Monitor respiratory response and inhaler technique. Patients should avoid spraying the medication into the eyes.

☕

Methylxanthines

Theophylline · Aminophylline

+

📍 Target Site Biochemical pathways within airway smooth-muscle and other tissues.

⚙️ Mechanism of Action Effects include phosphodiesterase inhibition and adenosine receptor antagonism, contributing to bronchodilation.

⚠️ Adverse Effects / Toxicity Nausea, vomiting, restlessness, tremor, tachycardia, cardiac arrhythmias and seizures.

🚨 Important Nursing Point Theophylline has a narrow therapeutic index and important drug interactions.

05 · Anti-inflammatory Therapy

Corticosteroids

Corticosteroids are primarily anti-inflammatory drugs. They are not simply medicines that immediately dilate the bronchi.

🔥

Corticosteroids

Budesonide · Beclometasone · Fluticasone · Prednisolone

+

Budesonide Beclometasone Fluticasone Prednisolone Hydrocortisone

📍 Target Site Intracellular glucocorticoid receptors within inflammatory and other responsive cells.

⚙️ Mechanism of Action Corticosteroids enter cells and bind glucocorticoid receptors. The drug-receptor complex alters gene transcription and reduces production of inflammatory mediators.

Steroid enters cell → Glucocorticoid receptor → Gene transcription altered → Inflammation ↓

⚠️ Inhaled Adverse Effects Oral candidiasis, dysphonia and throat irritation.

Systemic corticosteroids: Hyperglycaemia, hypertension, infection risk, osteoporosis, fluid retention, mood changes and adrenal suppression with significant prolonged exposure.

🩺 Nursing Considerations Teach patients using inhaled corticosteroids to rinse the mouth after administration. Monitor for adverse systemic effects when corticosteroids are used repeatedly or for prolonged periods.

🧠 Exam Point Corticosteroid → glucocorticoid receptor → inflammatory gene activity ↓ → airway inflammation ↓.

06 · Other Respiratory Drugs

Controllers, Secretions, Cough & Allergy Drugs

🧱

Leukotriene Receptor Antagonists

Montelukast · Zafirlukast

+

📍 Target Site Cysteinyl leukotriene receptors in the respiratory tract.

⚙️ Mechanism Blocks leukotriene effects, reducing bronchoconstriction, airway inflammation, vascular permeability and mucus secretion.

⚠️ Adverse Effects Headache, gastrointestinal symptoms and, rarely, clinically important neuropsychiatric symptoms.

💧

Mucolytics

Acetylcysteine · Carbocisteine

+

📍 Target Site Respiratory mucus and mucoproteins.

⚙️ Mechanism Acetylcysteine breaks disulfide bonds in mucus proteins, decreasing mucus viscosity and making secretions easier to clear.

Thick mucus → Disulfide bonds broken → Mucus becomes thinner → Easier clearance

⚠️ Adverse Effects Nausea, vomiting, unpleasant taste or odour, and bronchospasm in susceptible patients when inhaled.

🌊

Expectorants

Guaifenesin

+

📍 Target Site Respiratory tract secretions.

⚙️ Mechanism Facilitates less viscous respiratory secretions, making mucus easier to move and expectorate.

Remember Mucolytic = makes mucus less viscous.
Expectorant = helps secretions to be expelled.

🤐

Antitussives

Dextromethorphan

+

📍 Target Site Neural pathways involved in the central cough reflex.

⚙️ Mechanism Reduces activity of the cough reflex, increasing the threshold required to trigger coughing.

⚠️ Adverse Effects Drowsiness, dizziness, nausea and gastrointestinal discomfort.

🤧

H₁ Antihistamines

Cetirizine · Loratadine · Chlorpheniramine

+

📍 Target Site Histamine H₁ receptors in tissues involved in allergic responses.

⚙️ Mechanism Reduce histamine-mediated H₁ receptor signalling, reducing sneezing, nasal itching and rhinorrhoea.

⚠️ Adverse Effects First-generation antihistamines can cause sedation, dry mouth, blurred vision and reduced concentration.

👃

Nasal Decongestants

Oxymetazoline · Xylometazoline

+

📍 Target Site Adrenergic receptors in blood vessels of the nasal mucosa.

⚙️ Mechanism Vasoconstriction of nasal mucosal vessels reduces oedema and nasal congestion.

⚠️ Important Adverse Effect Excessive prolonged use of topical decongestants may cause rebound congestion.

Memory Tricks

Make the Mechanisms Stick

β₂ = Breathe Better

Stimulating β₂ receptors relaxes bronchial smooth muscle.

M₃ = Makes Airways Tight

Blocking M₃ receptors reduces cholinergic bronchoconstriction.

Steroids Stop Swelling

Corticosteroids primarily reduce airway inflammation.

07 · Rapid Revision

Respiratory Pharmacology at a Glance

Use this table for quick pharmacology and Nursing Council revision.

Class	Example	Target Site	Mechanism	Main Effect	Important Adverse Effect
β₂ agonist	Salbutamol	β₂ receptors on bronchial smooth muscle	↑ cAMP	Bronchodilation	Tremor, tachycardia, hypokalaemia
Antimuscarinic	Ipratropium	Muscarinic M₃ receptors	Blocks acetylcholine	Bronchodilation	Dry mouth
Corticosteroid	Budesonide	Intracellular glucocorticoid receptor	Alters inflammatory gene transcription	↓ airway inflammation	Oral candidiasis
Leukotriene antagonist	Montelukast	Leukotriene receptor	Blocks leukotriene signalling	↓ bronchoconstriction	Headache; neuropsychiatric effects reported
Methylxanthine	Theophylline	Airway smooth-muscle pathways	PDE inhibition and adenosine antagonism	Bronchodilation	Arrhythmias, seizures in toxicity
Mucolytic	Acetylcysteine	Respiratory mucus	Breaks disulfide bonds	Thinner mucus	Nausea, bronchospasm
Antitussive	Dextromethorphan	Central cough pathways	Suppresses cough reflex	Reduces coughing	Drowsiness, dizziness
H₁ antihistamine	Cetirizine	H₁ receptors	Reduces histamine signalling	↓ allergic symptoms	Drowsiness in some patients

08 · Nursing Responsibilities

What Should the Nurse Monitor?

🩺 Before Administration

Review the medication order and assess the patient's respiratory status, including respiratory rate, breathing pattern, breath sounds and oxygenation when indicated.

💨 Inhaler Technique

Correct inhaler technique is essential for effective drug delivery. Demonstrate the technique and ask the patient to demonstrate it back.

⚠️ Monitor Adverse Effects

Examples include tachycardia with beta₂ agonists, dry mouth with antimuscarinics and oral candidiasis with inhaled corticosteroids.

🎯 Evaluate Response

Determine whether respiratory symptoms, airflow, exercise tolerance and other relevant clinical indicators improve following treatment.

Test Yourself

Respiratory Pharmacology Quiz

Click an answer or use A, B, C or D on your keyboard.

Question 1 Score: 0

Respiratory Pharmacology for Nursing Students
Classification · Target Sites · Mechanisms · Adverse Effects · Nursing Considerations

Educational revision material. Medication use should follow current prescriptions, institutional protocols and relevant clinical guidelines.