Bronchodilator · Hyperkalemia treatment
Albuterol
Indications
- Acute bronchospasm in asthma and COPD exacerbations, intermittent or continuous
- Bronchospasm in ventilated or anesthetized patients, by in-line MDI or nebulizer
- Hyperkalemia, as an add-on that shifts potassium into cells (off-label)
- Bronchospasm in anaphylaxis that persists after IM epinephrine (off-label)
Dosing
| Where | Dose |
|---|---|
| Metabolic and electrolyte boluses | Albuterol: 10–20 mg nebulized |
Mechanism of action
Albuterol is a selective β2-adrenergic agonist, a partial agonist with less intrinsic efficacy than epinephrine. Receptor binding activates Gs, adenylyl cyclase and cAMP; protein kinase A then inhibits myosin light-chain kinase, lowers intracellular calcium and opens calcium-activated potassium channels, relaxing airway smooth muscle from the trachea to the terminal bronchioles. The same cAMP signal stimulates Na⁺/K⁺-ATPase in skeletal muscle, pushing potassium into cells, and drives glycogenolysis and glycolysis, raising glucose and lactate.
Pharmacology
- Respiratory: bronchodilation within minutes; PaO₂ can dip briefly as pulmonary vasodilation worsens V/Q matching
- Cardiovascular: tachycardia from cardiac β2 receptors, β1 at high doses and reflex vasodilation; T-wave flattening, QTc prolongation and ST depression (label)
- Metabolic: potassium falls by 30 min and stays down at least 2 h (10 and 20 mg nebulized lowered it 0.62 and 0.98 mEq/L, Allon 1989); glucose and lactate rise
- Neuromuscular: fine tremor (20% in label trials) and nervousness
Pharmacokinetics
| Onset | Inhaled: within 5 min |
|---|---|
| Peak | About 1 h |
| Duration | 3–4 h, up to 6 h |
| Half-life | 4–6 h (4.6 h inhaled; 3.9 h IV) |
| Distribution | Vd about 2 L/kg; under 20% of a nebulized dose is absorbed, the rest staying in the device or exhaled |
| Protein binding | About 10% |
| Metabolism | SULT1A3 sulfation in gut wall and liver to an inactive sulfate, no CYP; R-albuterol is sulfated faster, so S-albuterol accumulates |
| Elimination | Urine: after IV, 64% unchanged and 12% as sulfate (Morgan 1986) |
| Bioavailability | Oral 50% after first-pass sulfation |
Chemistry
- A saligenin (2-hydroxymethylphenol) ring replaces the catechol, so COMT cannot inactivate it; the bulky tert-butyl amine gives β2 selectivity and resists MAO
- Racemic: R-albuterol (levalbuterol) has about 100 times the β2 affinity of the S-isomer, but pure levalbuterol has not proved clinically better
- pKa values about 9.3 and 10.3: the amine is almost fully protonated at pH 7.4, so it is hydrophilic
- MDI 90 mcg base (108 mcg sulfate) per puff; nebulizer 2.5 mg/3 mL or 0.5% (5 mg/mL) concentrate for continuous use, pH 3–5; protect from light
Adverse effects and cautions
In the one-pagers
- Asthma and COPD ExacerbationsSevere asthma: Albuterol, repeated or continuous, plus ipratropium
- Aerosol Drugs and HumidityMucoactive and bland aerosols: Acetylcysteine 20%, 3–5 mL: Thick secretions: Bronchospasm: give with albuterol
- Electrolyte ImbalancesHyperkalemia: stabilize, shift, remove: Add-on shift: nebulized albuterol 10–20 mg, never alone. Bicarbonate mainly for metabolic acidosis.
- Pediatric Assessment and EmergenciesCroup, epiglottitis, bronchiolitis: Bronchiolitis: no routine albuterol or steroids
- Neonatal and Pediatric Respiratory CarePediatric airway emergencies: Bronchiolitis: nasal suction, O₂ if SpO₂ under 90%, high-flow up to 2 L/kg/min; no routine albuterol, steroids or chest physiotherapy.
- PFTs and Oxygen DeliverySpirometry: technique, patterns and bronchodilator response: Bronchodilator testing commonly gives four 100-µg puffs of albuterol by spacer and repeats spirometry about 15 minutes later. ERS/ATS 2022 counts a rise in FEV₁ or FVC of more than 10% of predicted; the 2005 rule, still on many reports, was at least 12% and 200 mL above baseline. Example: predicted FEV₁ 3.00 L, pre 1.80 L, post 2.15 L. T
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In the algorithms
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Sources
- FDA label: Ventolin HFA (2024)
- FDA label: albuterol inhalation solution 0.5%, Ritedose (2026)
- Morgan 1986 (IV and oral kinetics)
- Allon 1989 (hyperkalemia)
For education and exam preparation only. Follow your institution’s protocols. Typical adult values for study. Follow the order, the label and your institution's protocols.