Levosalbutamol Nebuliser Solution or Inhaler
Generic Name: Levosalbutamol (as Sulphate)
Therapeutic Class: Selective Beta-2 Agonist (Bronchodilator)
Indications
Levosalbutamol Inhalers and Nebuliser Solutions are "reliever" therapies used for the rapid management of bronchial constriction:
- Asthma: Treatment and prevention of bronchospasm in patients with reversible obstructive airway disease.
- COPD: Acute relief of airflow obstruction in chronic obstructive pulmonary disease, including chronic bronchitis and emphysema.
- Acute Exacerbations: Nebuliser solutions are preferred for severe respiratory distress where the patient cannot coordinate an inhaler.
- Exercise-Induced Bronchospasm: Prevention of symptoms before physical exertion.
Dosage & Administration
The dose should be adapted to the individual's needs.
- Metered Dose Inhaler (MDI):
- Adults and children (6+ years): 1–2 puffs every 4 to 6 hours as needed.
- Nebuliser Solution:
- Adults/Adolescents: 0.63 mg to 1.25 mg administered via nebulization three times daily.
- Children (6-11 years): 0.31 mg to 0.63 mg three times daily.
- Administration: For MDIs, use with a spacer for better lung deposition. For nebulisers, ensure the mist is inhaled over 5–15 minutes using a face mask or mouthpiece.
Description & Pharmacokinetics
Levosalbutamol is the pure (R)-enantiomer of the racemic mixture salbutamol, which possesses approximately 100-fold higher affinity for the $\beta_2$-receptor than the (S)-enantiomer.
Mechanism of Action: By binding to **$\beta_2$-adrenergic receptors**, it stimulates adenyl cyclase, increasing cyclic AMP. This relaxes the smooth muscles of all airways, from the trachea to the terminal bronchioles. It also inhibits the release of bronchoconstricting mediators from mast cells.
Pharmacokinetics:
Mechanism of Action: By binding to **$\beta_2$-adrenergic receptors**, it stimulates adenyl cyclase, increasing cyclic AMP. This relaxes the smooth muscles of all airways, from the trachea to the terminal bronchioles. It also inhibits the release of bronchoconstricting mediators from mast cells.
Pharmacokinetics:
- Onset: Within 5 to 10 minutes.
- Peak Effect: 60 to 90 minutes.
- Duration: 6 to 8 hours.
- Metabolism: Minimally metabolized in the lungs; the absorbed portion is conjugated in the liver.
Side Effects
- Common: Fine tremors, nervousness, headache, and dizziness.
- Cardiovascular: Palpitations, tachycardia, and changes in blood pressure.
- Respiratory: Throat irritation, cough, and rare paradoxical bronchospasm.
- Metabolic: Potentially significant hypokalemia and hyperglycemia at high doses.
Extra Important Information: Usage Insights
- The (R)-Isomer Advantage: Research suggests that Levosalbutamol provides effective bronchodilation with a lower risk of tachycardia and jitters compared to standard Salbutamol.
- Nebulizer Hygiene: Always clean the nebulizer cup and mask after each use to prevent bacterial growth and medication buildup.
- No "S-Isomer": By removing the (S)-isomer, Levosalbutamol avoids the isomer that has been linked to airway hyper-responsiveness.
Pregnancy & Lactation
- Pregnancy: Category C. It should be used only if the potential benefit outweighs the risk to the fetus. It is preferred over no treatment for acute asthma.
- Lactation: Caution is advised; it is unknown if it is excreted in human milk, though the systemic levels after inhalation are very low.
Storage
Store below 30°C in a cool, dry place. Protect nebuliser vials from light by keeping them in the foil pouch. Do not use if the solution is discolored.
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