levalbuterol
Brand: Xopenex
Prototype: albuterol
Drug Class: beta-2 adrenergic agonist (SABA)
Drug Family: bronchodilator
Subclass: R-enantiomer of albuterol — short-acting beta-2 agonist
Organ Systems: respiratory
Mechanism of Action
R-enantiomer of racemic albuterol; selectively activates beta-2 adrenergic receptors in bronchial smooth muscle, stimulating adenylyl cyclase, increasing cAMP, and activating PKA to phosphorylate myosin light chain kinase, causing bronchial smooth muscle relaxation and bronchodilation.
beta-2 adrenergic receptors (bronchial smooth muscle)
Indications
- acute bronchospasm (asthma, COPD)
- prevention of exercise-induced bronchospasm
Contraindications
- hypersensitivity to levalbuterol or albuterol
Adverse Effects
Common
- tachycardia
- tremor
- nervousness
- headache
- palpitations
Serious
- severe paradoxical bronchospasm
- hypokalemia (with high doses)
- lactic acidosis (rare, high doses in severe asthma)
Pharmacokinetics (ADME)
| Absorption | inhaled; systemic bioavailability approximately 10-20% via nebulization |
| Distribution | Vd approximately 660 L; crosses placenta |
| Metabolism | hepatic conjugation to inactive metabolites; some undergoes sulfoconjugation |
| Excretion | renal (predominantly as metabolites) |
| Half-life | approximately 3.3-4 hours |
| Onset | 5-15 minutes |
| Peak | 1-1.5 hours |
| Duration | 5-8 hours |
| Protein Binding | approximately 10% |
| Vd | approximately 660 L |
Drug Interactions
| Drug / Agent | Mechanism | Severity |
|---|---|---|
| non-selective beta-blockers | competitive antagonism reduces bronchodilatory effect and may precipitate severe bronchospasm | major |
| MAOIs and tricyclic antidepressants | potentiate cardiovascular effects of sympathomimetics | moderate |
| loop and thiazide diuretics | additive hypokalemia risk at high levalbuterol doses | moderate |
Nursing Considerations
- Administer via nebulizer; do not mix with other solutions unless compatibility is confirmed; unit-dose vials (0.31, 0.63, 1.25 mg) simplify dosing for pediatric patients.
- Monitor heart rate and oxygen saturation during and after nebulization; tachycardia and tremor are common; discontinue and notify provider if paradoxical bronchospasm occurs.
- Monitor serum potassium in patients receiving frequent doses or who are also on diuretics; high-dose beta-2 agonist therapy can cause clinically significant hypokalemia.
- The proposed clinical advantage of levalbuterol over racemic albuterol (fewer cardiovascular side effects) has not been consistently demonstrated in controlled trials; cost is significantly higher.
Clinical Pearls
- Levalbuterol is the R-enantiomer of racemic albuterol; the S-enantiomer (formerly believed to be inactive) may have pro-inflammatory properties, which was the rationale for developing levalbuterol as a purer bronchodilator.
- Clinical evidence has not consistently demonstrated a significant advantage of levalbuterol over racemic albuterol in efficacy or tolerability; most guidelines consider them therapeutically equivalent at equipotent doses.
Safety Profile
Pregnancy use-with-caution
Lactation use-with-caution
Renal Adjustment Not required
Hepatic Adjustment Not required
TDM Not required
Concordance Terms
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