NEET PG Respiratory Pharmacology Glossary 2026 — Bronchodilators, Antitussives & High-Yield Drugs

You're probably staring at a 20-page respiratory pharmacology chapter thinking "how am I supposed to remember all these drug names AND their mechanisms?" NEET PG loves testing respiratory drugs — 8-12 questions per year across pharmacology and medicine. The good news? Most questions test the same 25 high-yield drugs with predictable patterns.

This glossary breaks down every drug you need to know, organized by mechanism and clinical use. No fluff, just the exam-relevant facts that separate correct answers from attractive distractors.

Beta-2 Adrenergic Agonists (Bronchodilators)

The most tested drug class in respiratory pharmacology. NEET PG loves asking about onset time, duration, and selectivity.

Short-Acting Beta-2 Agonists (SABA)

Salbutamol (Albuterol)

• MOA: Selective beta-2 receptor agonist → increased cAMP → bronchodilation

• Onset: 5 minutes (inhaled), 15-30 minutes (oral)

• Duration: 4-6 hours

• Clinical use: Acute bronchospasm, status asthmaticus (first-line), exercise-induced asthma

• Side effects: Tremor, tachycardia, hypokalemia

• Exam point: Drug of choice for acute asthma attack

Terbutaline

• MOA: Beta-2 selective agonist with mild beta-1 activity

• Route: SC, inhaled, oral

• Duration: 4-6 hours

• Clinical use: Status asthmaticus when inhaled route not possible

• Side effects: More cardiac effects than salbutamol

• Exam point: Can be given subcutaneously in emergency

Long-Acting Beta-2 Agonists (LABA)

Salmeterol

• MOA: Beta-2 agonist with lipophilic side chain → prolonged receptor binding

• Onset: 20 minutes (slow)

• Duration: 12 hours

• Clinical use: Maintenance therapy (never alone), COPD

• Side effects: Same as SABA but longer-lasting

• Exam point: Black box warning — increased asthma-related deaths when used without corticosteroids

The Oncourse mnemonic engine generates memorable hooks like "SALBS: Short Acting = Salbutamol, Terbutaline; Long Acting = Salmeterol, Formoterol" — making drug classification instant recall rather than rote memorization. Formoterol

• MOA: Beta-2 agonist with rapid onset and long duration

• Onset: 5 minutes (fast like SABA)

• Duration: 12 hours

• Clinical use: Maintenance + rescue therapy, COPD

• Side effects: Similar to other LABAs

• Exam point: Only LABA suitable for rescue use due to rapid onset

Methylxanthines

High-yield for mechanism questions and drug interactions.

Theophylline

• MOA: Non-selective phosphodiesterase inhibition → increased cAMP + adenosine receptor antagonism

• Therapeutic range: 10-20 μg/mL (narrow therapeutic index)

• Clinical use: Second-line for asthma, COPD maintenance

• Side effects: CNS stimulation, cardiac arrhythmias, GI upset

• Drug interactions: CYP1A2 substrate (smoking decreases levels, ciprofloxacin increases)

• Exam point: Requires monitoring due to narrow therapeutic window

Aminophylline

• MOA: Theophylline + ethylenediamine (better solubility)

• Route: IV (for status asthmaticus)

• Clinical use: Severe acute asthma when beta-agonists fail

• Exam point: IV form of theophylline for emergency use

For tricky concepts like theophylline's drug interactions, Synapses flashcards use spaced repetition to surface these facts at optimal intervals before your exam — no more cramming the night before.

Anticholinergics (Muscarinic Antagonists)

NEET PG frequently tests the difference between short and long-acting anticholinergics.

Ipratropium

• MOA: M3 muscarinic receptor antagonist → reduced acetylcholine-induced bronchoconstriction

• Onset: 15-30 minutes

• Duration: 4-6 hours

• Clinical use: COPD (first-line), asthma (second-line)

• Side effects: Dry mouth, minimal systemic absorption

• Exam point: Preferred in COPD over beta-agonists

Tiotropium

• MOA: Long-acting M3 antagonist with kinetic selectivity

• Onset: 30 minutes

• Duration: 24 hours

• Clinical use: COPD maintenance (once daily)

• Side effects: Dry mouth, constipation

• Exam point: First-line maintenance therapy for COPD

Glycopyrrolate

• MOA: Long-acting anticholinergic

• Duration: 12-24 hours

• Route: Inhaled, injection

• Clinical use: COPD maintenance therapy

• Exam point: Alternative to tiotropium

Inhaled Corticosteroids (ICS)

Essential for maintenance therapy questions and side effect profiles.

Budesonide

• MOA: Glucocorticoid receptor agonist → anti-inflammatory gene transcription

• Bioavailability: Low systemic (high first-pass metabolism)

• Clinical use: Asthma maintenance, COPD with frequent exacerbations

• Side effects: Local — thrush, hoarseness; Systemic — growth retardation (children)

• Exam point: Preferred in pregnancy and children

Fluticasone

• MOA: High-potency corticosteroid with minimal systemic activity

• Formulations: Propionate (twice daily), furoate (once daily)

• Clinical use: Asthma maintenance, often combined with LABA

• Side effects: Similar to budesonide but higher potency

• Exam point: Available in combination with salmeterol

Beclomethasone

• MOA: Corticosteroid prodrug activated in lungs

• Clinical use: Asthma maintenance therapy

• Side effects: Higher systemic absorption than newer agents

• Exam point: Older agent, less commonly used now

Anti-Inflammatory Agents

Mast Cell Stabilizers Sodium Cromoglycate

• MOA: Mast cell membrane stabilization → prevents histamine release

• Clinical use: Prophylaxis (not acute treatment), exercise-induced asthma

• Route: Inhaled only

• Side effects: Minimal (cough, throat irritation)

• Exam point: Prophylactic only — no use in acute attack

Nedocromil

• MOA: Similar to cromoglycate but more potent

• Clinical use: Asthma prophylaxis, allergic conjunctivitis

• Side effects: Bitter taste, headache

• Exam point: Second-generation mast cell stabilizer

Leukotriene Modifiers

High-yield for asthma pathophysiology and drug classification.

Montelukast

• MOA: Leukotriene D4 (LTD4) receptor antagonist

• Clinical use: Asthma maintenance, allergic rhinitis, exercise-induced asthma

• Route: Oral (convenient for children)

• Side effects: Behavioral changes, suicidal ideation (rare)

• Exam point: Alternative to ICS in mild asthma

Zafirlukast

• MOA: LTD4 receptor antagonist

• Clinical use: Similar to montelukast

• Drug interactions: CYP2C9 substrate

• Side effects: Hepatotoxicity (rare)

• Exam point: Requires liver function monitoring

Zileuton

• MOA: 5-lipoxygenase inhibitor → blocks leukotriene synthesis

• Clinical use: Asthma with aspirin sensitivity

• Side effects: Hepatotoxicity, drug interactions (CYP1A2 inhibitor)

• Exam point: Only leukotriene synthesis inhibitor (others are receptor antagonists)

When practicing MCQs about leukotriene pathways, the AI explanation chat breaks down why zileuton blocks synthesis while montelukast blocks receptors — turning confusion into clarity at the question level.

Antitussives

Frequently tested for mechanism and central vs peripheral action.

Codeine

• MOA: Opioid μ-receptor agonist in medulla cough center

• Clinical use: Dry cough suppression

• Side effects: Sedation, constipation, respiratory depression

• Contraindications: Children <12 years, CYP2D6 poor metabolizers

• Exam point: Central antitussive with addiction potential

Dextromethorphan

• MOA: NMDA receptor antagonist + sigma receptor → cough suppression

• Clinical use: Non-prescription dry cough relief

• Side effects: Minimal at therapeutic doses, abuse potential at high doses

• Exam point: Non-opioid central antitussive

Noscapine (Pholcodine)

• MOA: Central cough suppression without respiratory depression

• Clinical use: Dry cough in patients where opioids contraindicated

• Side effects: Minimal sedation, no addiction

• Exam point: Non-opioid antitussive with better safety profile

Expectorants and Mucolytics

Important for differentiating mechanism of action.

Ambroxol

• MOA: Increases surfactant production + mucociliary clearance

• Clinical use: Productive cough, COPD with thick secretions

• Route: Oral, injection

• Side effects: GI upset, rash

• Exam point: Metabolite of bromhexine

Bromhexine

• MOA: Mucus depolymerization + increased serous secretion

• Clinical use: Thick, tenacious sputum

• Metabolism: Converted to ambroxol (active metabolite)

• Exam point: Prodrug for ambroxol

Acetylcysteine

• MOA: Breaks disulfide bonds in mucus → reduced viscosity

• Clinical use: Cystic fibrosis, COPD, paracetamol poisoning antidote

• Route: Inhaled, oral, IV

• Side effects: Bronchospasm (with inhalation), nausea

• Exam point: Dual use as mucolytic and antidote

Guaifenesin

• MOA: Increases respiratory tract secretions → easier expectoration

• Clinical use: Dry to productive cough conversion

• Side effects: Nausea, vomiting at high doses

• Exam point: Most common OTC expectorant

Anti-Asthma Biologics

Emerging area with increasing exam importance.

Omalizumab

• MOA: Anti-IgE monoclonal antibody

• Clinical use: Severe allergic asthma with elevated IgE

• Route: Subcutaneous injection

• Side effects: Injection site reactions, anaphylaxis risk

• Exam point: First biologic for asthma

Mepolizumab

• MOA: Anti-IL-5 monoclonal antibody → eosinophil reduction

• Clinical use: Severe eosinophilic asthma

• Route: Subcutaneous injection

• Exam point: Targets eosinophil-driven inflammation

High-Yield Exam Patterns

Status Asthmaticus Management

1. First-line: High-dose salbutamol (nebulized) + systemic corticosteroids 2. Second-line: Ipratropium + salbutamol combination 3. Third-line: IV aminophylline or magnesium sulfate 4. Last resort: IV salbutamol or mechanical ventilation

COPD vs Asthma First-Line Therapy

• COPD: Tiotropium (LAMA) or combined LAMA/LABA

• Asthma: ICS (budesonide/fluticasone) ± LABA for maintenance

Beta-Blocker Poisoning Bronchospasm

• Drug of choice: Ipratropium (anticholinergic)

• Avoid: Beta-agonists (competitive inhibition by beta-blockers)

Cough Reflex Center

• Location: Medulla oblongata

• Central antitussives: Codeine, dextromethorphan, noscapine

• Mechanism: μ-opioid receptor agonism (codeine) vs NMDA antagonism (dextromethorphan)

Drug Interaction Quick Reference

For complex interactions like these, targeted flashcards ensure you recall the mechanism behind each interaction — not just memorizing lists.

Frequently Asked Questions

Which bronchodilator has the fastest onset of action?

Salbutamol and formoterol both have 5-minute onset when inhaled. Salmeterol takes 20 minutes despite being long-acting.

What's the difference between theophylline and aminophylline?

Aminophylline is theophylline + ethylenediamine for better water solubility. It's used IV in emergencies. Theophylline is oral maintenance therapy.

Why cant LABAs be used alone in asthma?

LABAs can mask worsening inflammation while bronchodilating, leading to delayed recognition of severe exacerbations. Always combine with ICS.

Which antitussive is safest in children?

Dextromethorphan for children >4 years. Codeine is contraindicated under 12 years due to variable metabolism and respiratory depression risk.

What's first-line for exercise-induced asthma?

Short-acting beta-2 agonist (salbutamol) 15 minutes before exercise. Alternative: montelukast daily or cromoglycate before activity.

How do you remember anticholinergic duration?

"I-T rule": Ipratropium = short (4-6 hours), Tiotropium = long (24 hours). Both start with different letters for different durations.

Master respiratory pharmacology with the complete NEET PG pharmacology question bank and comprehensive lessons covering every high-yield drug. The systematic flashcard approach ensures nothing slips through the cracks during your final revision.

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