Generic Name: Levosalbutamol
Therapeutic Class: Selective Beta-2 Agonist / Bronchodilator
Indications
Levosalbutamol is the single (R)-isomer of the racemic mixture salbutamol. It is indicated for:
- Asthma Management: Treatment or prevention of bronchospasm in adults, adolescents, and children with reversible obstructive airway disease.
- COPD: Relief of acute bronchoconstriction in patients with chronic obstructive pulmonary disease.
- Acute Bronchitis: Management of respiratory distress and wheezing.
- Reduced Side Effect Profile: Often preferred for patients who experience significant tachycardia or tremors with standard Salbutamol.
Dosage & Administration
Dosage varies by age and the severity of the respiratory condition.
- Adults and Adolescents (12+ years):
- Syrup: 1-2 mg (5-10 ml) three times daily.
- Tablet: 1 mg or 2 mg three times daily.
- Inhaler (MDI): 1-2 puffs (50-100 mcg) every 4 to 6 hours as needed.
- Children (6–11 years): 0.5 mg to 1 mg (2.5-5 ml syrup) three times daily.
- Nebulizer Solution: 0.63 mg to 1.25 mg administered via nebulization three times daily.
- Note: Patients should not increase the dose or frequency without medical consultation.
Description & Pharmacokinetics
Levosalbutamol is the active (R)-enantiomer of salbutamol. The (S)-enantiomer found in racemic salbutamol is thought to be inert or potentially pro-inflammatory.
Mechanism of Action: It acts as a highly selective **$\beta_2$-adrenergic receptor agonist**. Activation of these receptors on bronchial smooth muscle leads to the activation of adenyl cyclase and to an increase in the intracellular concentration of cyclic AMP. This results in the relaxation of bronchial smooth muscle and inhibits the release of mediators from mast cells in the airway.
Pharmacokinetics:
Mechanism of Action: It acts as a highly selective **$\beta_2$-adrenergic receptor agonist**. Activation of these receptors on bronchial smooth muscle leads to the activation of adenyl cyclase and to an increase in the intracellular concentration of cyclic AMP. This results in the relaxation of bronchial smooth muscle and inhibits the release of mediators from mast cells in the airway.
Pharmacokinetics:
- Onset: Rapid onset, typically within 5–10 minutes after inhalation.
- Duration: The bronchodilatory effect lasts for approximately 6 to 8 hours, which is slightly longer than racemic salbutamol.
- Metabolism: Metabolized in the liver to an inactive sulfate conjugate.
- Excretion: Primarily eliminated through urine.
Side Effects
- Central Nervous System: Dizziness, nervousness, tremor, and headache.
- Cardiovascular: Palpitations, tachycardia (less frequent than with racemic salbutamol), and chest pain.
- Respiratory: Sore throat, dry mouth, and paradoxical bronchospasm.
- Systemic: Flu-like syndrome, leg cramps, and hypokalemia (at high doses).
Extra Important Information: Usage Insights
- Enantiomer Benefit: Because it lacks the (S)-salbutamol isomer, it is associated with fewer cardiac side effects like racing heart or jitteriness.
- Emergency Use: Like all SABAs, this is a reliever medication. It does not treat the underlying inflammation of asthma.
- Monitoring: Patients with pre-existing heart disease or hyperthyroidism should be monitored closely.
Pregnancy & Lactation
- Pregnancy: Category C. Use during pregnancy only if the potential benefit justifies the potential risk to the fetus.
- Lactation: It is unknown whether levosalbutamol is excreted in human milk. Caution should be exercised when administered to nursing women.
Storage
Store at room temperature (below 30°C). Protect from light and moisture. Inhaler canisters should be kept away from extreme heat or open flames.
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