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Albuterol

Albuterol (Salbutamol)

ProAir HFA Ventolin HFA Proventil HFA Accuneb VoSpire ER

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Updated: December 06, 2025

Overview

Albuterol (salbutamol) is a short-acting β₂-adrenergic receptor agonist (SABA) primarily used as a bronchodilator for respiratory conditions. It rapidly relaxes bronchial smooth muscle, increasing airflow to the lungs within minutes of administration. Available in inhalation (MDI, nebulizer), oral, and intravenous formulations, it is a first-line rescue medication for acute asthma exacerbations and bronchospasm. As a selective β₂-agonist, albuterol minimizes cardiac side effects associated with non-selective β-agonists. Its quick onset but short duration (4-6 hours) makes it ideal for acute symptom relief rather than maintenance therapy. The drug is extensively metabolized and has a well-established safety profile when used appropriately.

Drug Class

Short-acting β₂-adrenergic agonist (SABA); Bronchodilator; Anti-asthmatic agent

Mechanism of Action

Albuterol selectively stimulates β₂-adrenergic receptors on bronchial smooth muscle, activating adenylate cyclase. This increases intracellular cyclic AMP (cAMP), leading to protein kinase A activation. Subsequent phosphorylation of target proteins causes: • Relaxation of bronchial smooth muscle via reduced myosin light chain kinase activity • Inhibition of mast cell mediator release (histamine, leukotrienes) • Enhanced mucociliary clearance

Pharmacokinetics

Absorption: Rapid after inhalation; oral bioavailability ~50% due to first-pass metabolism; peak plasma concentration in 2-3 hours (oral). Distribution: Distributed to lungs and other tissues; plasma protein binding 10%; steady-state volume of distribution ~156L. Metabolism: Extensively metabolized in liver via sulfate conjugation and CYP450-mediated oxidation to inactive metabolites. Excretion: Primarily renal (60-80% as metabolites); fecal excretion accounts for <20%. Half-life: Inhalation: 3.8 hours; Oral: 4-6 hours; Extended-release: 7-8 hours.

Pharmacodynamics

• Bronchodilation: Onset within 5-15 min (inhalation), peak at 60-90 min, duration 4-6 hours • Cardiovascular effects: Dose-dependent tachycardia via β₁ stimulation; peripheral vasodilation may cause mild hypotension • Metabolic effects: Transient hyperglycemia, hypokalemia via β₂-mediated potassium shift into cells • Skeletal muscle: Enhances tremor through β₂ agonism in skeletal muscle

Indications

• Asthma: Acute bronchospasm relief and prevention of exercise-induced bronchospasm • Chronic Obstructive Pulmonary Disease (COPD): Symptomatic relief of bronchospasm • Bronchiolitis: Nebulized formulation for wheezing in infants (off-label) • Hyperkalemia: Intravenous use for acute potassium lowering in renal failure

Contraindications

Absolute: • Hypersensitivity to albuterol or formulation components • Tachyarrhythmias Relative: • Uncontrolled hypertension • Seizure disorders • Diabetes mellitus • Hyperthyroidism

Dosage & Administration

Asthma/COPD (MDI): 90 mcg/puff; 1-2 puffs every 4-6 hours PRN Nebulization (0.5% solution): 2.5mg every 4-6 hours PRN; severe exacerbations: 5mg Exercise-induced bronchospasm: 2 puffs 15-30 minutes pre-exercise Pediatric nebulization (≥2 years): 0.63-2.5mg every 4-6 hours Oral extended-release: 4-8mg every 12 hours (adults)

Special Populations

Pediatric: Not recommended for children <2 years in nebulized form without monitoring; MDI use requires spacer Geriatric: Increased sensitivity to tachycardia/tremor; initiate lower doses Renal impairment: No dose adjustment needed; monitor for hypokalemia Hepatic impairment: Use with caution; reduced metabolism may prolong effects

Adverse Effects

Common (>10%): • Tachycardia (palpitations) • Tremor (β₂ effect on skeletal muscle) • Nervousness/anxiety • Throat irritation (inhalation) Serious (<1%): • Paradoxical bronchospasm (immediate discontinuation required) • Angina or myocardial ischemia • Severe hypokalemia (serum K⁺ <2.5 mmol/L) • Anaphylaxis

Drug Interactions

• Beta-blockers: Antagonize bronchodilator effects (avoid non-selective β-blockers) • Diuretics: Enhanced hypokalemia risk (monitor potassium) • MAO inhibitors/Tricyclic antidepressants: Potentiate cardiovascular effects • Digoxin: Increased risk of arrhythmias during hypokalemia

Warnings & Precautions

• Black Box Warning: Asthma-related deaths increased with SABA overuse (use only as rescue, not maintenance) • Cardiovascular risk: May exacerbate angina, hypertension, or arrhythmias • Paradoxical bronchospasm: Immediately discontinue if worsening wheezing occurs • Hypokalemia: Monitor potassium in acute/high-dose use • Tolerance: Regular use may reduce bronchodilator efficacy

Pregnancy & Lactation

Pregnancy: FDA Category C; use if benefit justifies risk. Human data show no major malformations but may delay labor. Monitor for maternal tachycardia/hypokalemia. Lactation: Excreted in breast milk (0.7% maternal dose); consider pump/discard 4 hours post-dose. AAP considers compatible with breastfeeding.

Monitoring Parameters

• Pulmonary function: Peak flow/spirometry pre/post dosing • Cardiovascular status: Heart rate, blood pressure, ECG in high-risk patients • Serum potassium: Especially with high-dose/IV use • Blood glucose: In diabetic patients • Therapeutic efficacy: Symptom frequency/rescue use to assess control

Patient Counseling

• Correct inhaler technique: Shake MDI, exhale fully, inhale slowly while activating, hold breath 10s • Not for daily prevention: Use only for acute symptoms (exceeding 2×/week indicates poor control) • Rinse mouth after inhalation to prevent thrush/hoarseness • Seek immediate care if needing >4 puffs in 20 min without relief • Store canister at room temperature; discard after expiration or when counter reads zero

Storage & Stability

MDI: Store at 20-25°C (68-77°F); avoid freezing/puncturing. Discard when counter reads 000 or after expiration. Do not store in vehicles >120°F. Nebulizer solution: Unopened vials at 2-25°C (36-77°F); protect from light. Use opened vials within 1 week.

Clinical Pearls

• Overuse (>1 canister/month) indicates poor asthma control requiring controller therapy • MDI with spacer = nebulizer efficacy for mild-moderate exacerbations • Hypokalemia most significant with IV dosing in ICU settings • Distinguish true tolerance (receptor downregulation) from worsening disease • Combine with anticholinergics for severe asthma/COPD exacerbations

References

• Global Initiative for Asthma (GINA). Global Strategy for Asthma Management and Prevention (2023). • National Institutes of Health. National Asthma Education and Prevention Program Expert Panel Report 3 (2020). • Lexicomp. Albuterol Drug Monograph. Wolters Kluwer Clinical Drug Information (2023). • FDA Prescribing Information: ProAir HFA (2023). • Nelson HS. Beta-adrenergic bronchodilators. N Engl J Med. 1995;333(8):499-506.