Introduction
Xopenex (levalbuterol hydrochloride) is a short-acting beta-2 adrenergic agonist (SABA) bronchodilator used for the treatment and prevention of bronchospasm in patients with reversible obstructive airway disease. It is the (R)-enantiomer of the racemic albuterol mixture, developed to potentially provide enhanced bronchodilatory effects with reduced side effects compared to racemic albuterol.
Mechanism of Action
Levalbuterol selectively stimulates beta-2 adrenergic receptors in bronchial smooth muscle. This stimulation activates adenylate cyclase, converting ATP to cyclic-3',5'-adenosine monophosphate (cAMP). Increased intracellular cAMP levels result in relaxation of bronchial smooth muscle and inhibition of immediate hypersensitivity mediator release from mast cells. The (R)-enantiomer is responsible for virtually all of the bronchodilatory activity, while the (S)-enantiomer in racemic albuterol may contribute to increased side effects and potentially pro-inflammatory effects.
Indications
- Treatment or prevention of bronchospasm in patients with reversible obstructive airway disease (e.g., asthma)
- Exercise-induced bronchospasm prevention
Dosage and Administration
Inhalation Solution (0.31 mg, 0.63 mg, 1.25 mg per 3 mL vial):- Adults and adolescents ≥12 years: 0.63 mg administered three times daily by nebulization, every 6-8 hours
- Maximum dose: 1.25 mg three times daily
- Children 6-11 years: 0.31 mg administered three times daily by nebulization
- Not recommended for children under 6 years
- Use with a standard jet nebulizer connected to an air compressor
- Administer over approximately 5-15 minutes
- Dosing interval: every 6-8 hours as needed
- Renal impairment: No dosage adjustment required
- Hepatic impairment: Use with caution
Pharmacokinetics
Absorption: Rapidly absorbed following inhalation; systemic bioavailability approximately 90-100% of the nebulized dose Distribution: Moderate protein binding (55%); distributes to tissues throughout the body Metabolism: Extensively metabolized by conjugation to sulfate conjugates; minimal hepatic metabolism via CYP450 system Elimination: Primarily excreted in urine (70-90%) as metabolites; elimination half-life approximately 3.3-4.0 hoursContraindications
- Hypersensitivity to levalbuterol, albuterol, or any component of the formulation
- History of hypersensitivity reactions to any sympathomimetic amine
Warnings and Precautions
Cardiovascular Effects: May cause significant cardiovascular effects including hypertension, tachycardia, arrhythmias, and ECG changes. Use with extreme caution in patients with cardiovascular disorders (coronary insufficiency, cardiac arrhythmias, hypertension) Paradoxical Bronchospasm: Can occur with immediate increase in wheezing after dosing; discontinue immediately if occurs Hypokalemia: May decrease serum potassium levels through intracellular shifting; monitor particularly in patients at risk Diabetes: May increase blood glucose levels; monitor glucose in diabetic patients Seizure Disorders: May exacerbate condition due to CNS stimulation Thyrotoxicosis: May aggravate cardiovascular symptoms MAO inhibitor/TCAs: Concomitant use may potentiate cardiovascular effectsDrug Interactions
Beta-blockers: May antagonize bronchodilator effects; avoid non-selective beta-blockers Diuretics: May potentiate hypokalemic effects; monitor potassium levels Digoxin: May decrease serum digoxin concentrations; monitor levels MAO inhibitors/Tricyclic antidepressants: May potentiate cardiovascular effects Other sympathomimetics: Additive cardiovascular effects; use with cautionAdverse Effects
Most common (>5%):- Nervousness (8-12%)
- Tremor (5-9%)
- Headache (5-7%)
- Tachycardia (5-7%)
- Dizziness (5-6%)
- Pharyngitis (5-6%)
- Cardiovascular: Angina, hypertension, arrhythmias, ECG changes
- Metabolic: Hypokalemia, hyperglycemia
- Respiratory: Paradoxical bronchospasm
- Allergic: Urticaria, angioedema, anaphylaxis
Monitoring Parameters
- Pulmonary function tests (FEV1, peak flow)
- Cardiovascular status (heart rate, blood pressure, ECG if indicated)
- Serum potassium levels (especially with high doses or concomitant diuretics)
- Blood glucose in diabetic patients
- Clinical signs of bronchospasm
- Adverse effect profile
Patient Education
- Use exactly as prescribed; do not exceed recommended dosage
- Proper nebulizer technique and maintenance
- Recognize signs of worsening asthma requiring medical attention
- Not for use as a rescue medication for acute attacks
- Report chest pain, palpitations, tremors, or nervousness
- Inform all healthcare providers of Xopenex use
- Store at controlled room temperature; protect from light
- Discard solution if discolored
References
1. FDA Prescribing Information: Xopenex (levalbuterol HCl) inhalation solution. Revised 2022. 2. Nelson HS, et al. The efficacy and safety of levalbuterol compared with racemic albuterol. J Allergy Clin Immunol. 2000;105(4):703-710. 3. Truitt T, et al. Levalbuterol compared to racemic albuterol: efficacy and outcomes in patients hospitalized with COPD or asthma. Chest. 2003;123(1):128-135. 4. Global Initiative for Asthma (GINA). Global Strategy for Asthma Management and Prevention. 2023. 5. Drug Facts and Comparisons. Wolters Kluwer Health Inc. 2023. 6. Micromedex Solutions. Levalbuterol. Truven Health Analytics. 2023.