Usage
Levosalbutamol is prescribed for the prevention and treatment of bronchospasm in conditions such as asthma and chronic obstructive pulmonary disease (COPD). It provides quick relief from symptoms like wheezing, coughing, and shortness of breath. Pharmacologically, it is classified as a short-acting beta2-adrenergic agonist (SABA) bronchodilator. Levosalbutamol works by selectively stimulating beta2-adrenergic receptors in the lungs, leading to relaxation of the airway smooth muscle and bronchodilation.
Alternate Names
Levosalbutamol is also known as levalbuterol. Brand names include Xopenex and Xopenex HFA. It may be marketed under other brand names regionally.
How It Works
Pharmacodynamics: Levosalbutamol acts on beta2-adrenergic receptors in the lungs, activating adenyl cyclase, which increases intracellular cyclic AMP. This leads to activation of protein kinase A, inhibiting myosin phosphorylation and lowering intracellular calcium, causing smooth muscle relaxation and bronchodilation.
Pharmacokinetics: Levosalbutamol is rapidly absorbed after inhalation. It is metabolized primarily in the liver but up to 12 times faster than the (S)-enantiomer of albuterol. The primary route of elimination is renal excretion. The half-life is approximately 3.3-4 hours.
Mode of Action: Levosalbutamol selectively binds to beta2-adrenergic receptors on airway smooth muscle cells, initiating a cascade that results in bronchodilation.
Receptor Binding, Enzyme Inhibition, or Neurotransmitter Modulation: The drug acts via receptor binding (beta2-adrenergic receptors).
Elimination Pathways: Primarily renal excretion.
Dosage
Standard Dosage
Adults:
- Nebulizer: 0.63 mg three times daily, every 6-8 hours. The dose may be increased to 1.25 mg three times daily if needed, with close monitoring.
- Metered-Dose Inhaler (MDI): Two puffs (90 mcg) every 4-6 hours as needed. Some patients may only require one puff every 4 hours.
Children:
- Nebulizer:
- 6-11 years: 0.31 mg three times a day. Maximum dose: 0.63 mg three times a day.
- <6 years: Use and dose must be determined by a doctor. Clinical trials in this age group have not demonstrated efficacy for nebulized Levosalbutamol.
- MDI:
- ≥4 years: Two puffs (90 mcg) every 4-6 hours or one puff (45 mcg) every 4 hours. Maximum dose: Two puffs every 4 hours.
- <4 years: Safety and efficacy not established.
Special Cases:
- Elderly Patients: Start with 0.63 mg three times a day via nebulizer.
- Patients with Renal Impairment: Use with caution; dose adjustment may be necessary.
- Patients with Hepatic Dysfunction: No specific dose adjustment is typically required.
- Patients with Comorbid Conditions: Use with caution in patients with cardiovascular disease, hypertension, cardiac arrhythmias, convulsive disorders, hyperthyroidism, or diabetes mellitus. Monitor potassium levels, especially in patients with these conditions.
Clinical Use Cases
Dosage in these settings should be individualized based on patient response and clinical status. Consult specialist guidelines.
- Intubation: May be used before or after intubation to manage bronchospasm.
- Surgical Procedures: Can be administered to prevent or treat bronchospasm during or after surgery.
- Mechanical Ventilation: May be utilized to facilitate ventilation in patients experiencing bronchospasm.
- Intensive Care Unit (ICU) Use: Dosage should be titrated to effect based on patient’s respiratory status.
- Emergency Situations: Higher doses may be required in acute exacerbations of bronchospasm.
Dosage Adjustments
Dose adjustments should be considered in patients with renal or hepatic impairment, diabetes, and cardiovascular disease. Monitor patients for hypokalemia and hyperglycemia.
Side Effects
Common Side Effects:
Headache, tremor, nervousness, dizziness, tachycardia, palpitations, nausea, vomiting, muscle cramps, and throat irritation.
Rare but Serious Side Effects:
Allergic reactions (urticaria, angioedema, rash, bronchospasm, anaphylaxis), paradoxical bronchospasm, hypokalemia, hyperglycemia, and cardiac arrhythmias.
Long-Term Effects:
Tolerance to bronchodilator effects with chronic overuse.
Adverse Drug Reactions (ADR):
Severe allergic reactions, paradoxical bronchospasm, and significant hypokalemia.
Contraindications
Hypersensitivity to levosalbutamol or albuterol.
Drug Interactions
Beta-blockers (especially non-selective), diuretics, digoxin, MAO inhibitors, tricyclic antidepressants, other sympathomimetics (e.g., amphetamine, dobutamine). Consult a comprehensive drug interaction resource for a full list of potential interactions.
Pregnancy and Breastfeeding
Pregnancy Safety Category: C (Consult a doctor) - potential to affect uterine contractility.
Use only if potential benefit outweighs risk.
Breastfeeding: Limited data; a decision should be made to discontinue breastfeeding or the drug, considering the importance of the drug to the mother. It is unknown if levosalbutamol is excreted in human milk.
Drug Profile Summary
- Mechanism of Action: Beta2-adrenergic agonist, relaxes airway smooth muscle.
- Side Effects: Headache, tremor, tachycardia, palpitations, nausea, hypokalemia. Rarely, allergic reactions or paradoxical bronchospasm.
- Contraindications: Hypersensitivity to levosalbutamol or albuterol.
- Drug Interactions: Beta-blockers, diuretics, digoxin, MAOIs, TCAs.
- Pregnancy & Breastfeeding: Use with caution. Consult a doctor.
- Dosage: See detailed dosage guidelines above.
- Monitoring Parameters: Respiratory rate, heart rate, oxygen saturation, potassium levels, blood glucose levels (in diabetics).
Popular Combinations
Levosalbutamol is often used in combination with inhaled corticosteroids (e.g., beclomethasone, fluticasone) for long-term asthma management. It is also combined with ipratropium bromide for the treatment of COPD.
Precautions
- General Precautions: Assess for allergies, cardiovascular disease, diabetes, hyperthyroidism, and renal/hepatic impairment before initiating therapy.
- Specific Populations: See “Special Cases” under Dosage.
- Lifestyle Considerations: Avoid alcohol as it can worsen side effects like drowsiness. Caution with driving or operating machinery due to potential dizziness and drowsiness.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Levosalbutamol?
A: See detailed dosage guidelines above.
Q2: How quickly does Levosalbutamol work?
A: Onset of action is typically within 5-10 minutes after inhalation.
Q3: How long does the effect of Levosalbutamol last?
A: The bronchodilator effect usually lasts for 3-6 hours.
Q4: Can Levosalbutamol be used during pregnancy?
A: It should only be used during pregnancy if the potential benefit outweighs the potential risk to the fetus.
Q5: Is Levosalbutamol safe for breastfeeding mothers?
A: Limited data are available. A decision should be made whether to discontinue breastfeeding or the drug, considering the importance of the drug to the mother.
Q6: What are the common side effects of Levosalbutamol?
A: Common side effects include headache, tremor, nervousness, dizziness, tachycardia, and palpitations.
Q7: What should I do if a patient experiences paradoxical bronchospasm after using Levosalbutamol?
A: Discontinue Levosalbutamol immediately and consider alternative bronchodilator therapy.
Q8: Are there any drug interactions I should be aware of with Levosalbutamol?
A: Yes, Levosalbutamol can interact with beta-blockers, diuretics, digoxin, MAOIs, and TCAs. Consult a drug interaction resource for a comprehensive list.
Q9: Can Levosalbutamol affect blood glucose levels?
A: Yes, it can cause a rise in blood glucose levels. Monitor diabetics carefully and adjust insulin or other antidiabetic medications as necessary.
Q10: What is the difference between levosalbutamol and albuterol (salbutamol)?
A: Levosalbutamol is the single (R)-isomer of albuterol, which is a racemic mixture of (R)- and (S)- isomers. Levosalbutamol is considered more selective for beta2-adrenergic receptors, potentially leading to fewer side effects.
