Arolax

Approved Indications:

• Bronchial Asthma:
  Relief and prevention of bronchospasm in patients with reversible obstructive airway disease.
• Chronic Obstructive Pulmonary Disease (COPD):
  Management of acute exacerbations of bronchospasm.
• Exercise-Induced Bronchospasm (EIB):
  Prevention when administered before exercise.

Clinically Accepted Off-Label Uses:

• Adjunct therapy in hyperkalemia to promote intracellular potassium shift (hospital setting).

Adults:

• Inhalation Solution (via nebulizer):
  0.63 mg to 1.25 mg every 6–8 hours as needed.
  Maximum: 2.5 mg per dose.
• MDI:
  2 inhalations (90 mcg total) every 4–6 hours as needed.
  Do not exceed 12 inhalations per day.
• Oral Tablets:
  2 mg, taken 2–3 times daily.
• Oral Syrup:
  1–2 mg three times daily.

Pediatrics (6–12 years):

• Nebulization:
  0.31 mg to 0.63 mg every 6–8 hours.
• MDI:
  1 to 2 puffs (45 mcg each) every 4–6 hours.

Elderly:

• Start at the lower end of dosing due to increased cardiac sensitivity.

Renal Impairment:

• Use with caution; monitor renal function and electrolytes.

Hepatic Impairment:

• No specific adjustments; monitor for adverse effects.

Levosalbutamol is the (R)-enantiomer of racemic salbutamol. It selectively activates beta-2 adrenergic receptors in bronchial smooth muscle, stimulating cyclic AMP (cAMP) production. Elevated cAMP levels lead to relaxation of bronchial smooth muscle, causing bronchodilation. Compared to the racemic mixture, the (R)-isomer exhibits stronger beta-2 selectivity, enhanced bronchodilation, and fewer beta-1-mediated cardiac side effects.

• Absorption: Rapid after inhalation or oral intake.
• Bioavailability: ~25–30% (inhalation), ~40% (oral).
• Onset of Action: 5–15 minutes (inhalation).
• Peak Effect: 1–2 hours.
• Duration: 4–6 hours.
• Protein Binding: ~50%.
• Metabolism: Hepatic sulfate conjugation; minimal CYP450 involvement.
• Half-life: 3–6 hours.
• Excretion: Primarily renal as metabolites and unchanged drug.

• Pregnancy:
  Category C – Animal studies show risk; use only if benefits outweigh potential risks. No adequate human studies.
• Lactation:
  Unknown if excreted in breast milk. Use with caution. No documented adverse effects in nursing infants; monitor if used.

• Primary Class: Bronchodilator
• Subclass: Short-Acting Beta-2 Agonist (SABA)

• Known hypersensitivity to levosalbutamol or any component of the formulation
• History of paradoxical bronchospasm with beta-agonists
• Severe cardiac disorders (e.g., arrhythmias, hypertrophic cardiomyopathy)
• Use during acute myocardial infarction (with caution)

• Paradoxical Bronchospasm: Discontinue immediately if it occurs.
• Cardiovascular Effects: Use cautiously in patients with heart disease, hypertension, or arrhythmias.
• Seizures: May lower threshold; monitor in epileptic patients.
• Hypokalemia: Risk increases with high doses or when used with diuretics.
• Hyperglycemia: Temporary increases in blood sugar may occur.
• Overuse Warning: Frequent use (>2 times/week) may indicate poor asthma control; reassess therapy.

Common (≥1%):

• Neurologic: Tremor, headache, dizziness
• Respiratory: Throat irritation, cough, paradoxical bronchospasm
• Cardiovascular: Palpitations, tachycardia
• Gastrointestinal: Nausea

Less Common/Serious:

• Chest pain, hypertension
• Hypokalemia
• Muscle cramps
• Allergic reactions (rash, urticaria, anaphylaxis – rare)

• Beta-blockers: May reduce bronchodilation (especially non-selective agents).
• MAO Inhibitors & Tricyclic Antidepressants: May increase cardiovascular effects.
• Diuretics & Corticosteroids: Increase risk of hypokalemia.
• Digoxin: May reduce serum levels.
• Other Sympathomimetics: Additive cardiovascular effects possible.

Enzyme Systems:

• Minimal interaction with CYP450 isoenzymes. Not primarily metabolized via CYP3A4.

• GINA 2023 (Global Initiative for Asthma):
• Recommends combining SABA with inhaled corticosteroids for long-term control; monotherapy use should be minimized.
• FDA Labeling Update:
• Emphasizes risks of paradoxical bronchospasm and cardiovascular monitoring in children and elderly.
• Recent Studies:
• Indicate improved safety and tolerability of levosalbutamol over racemic salbutamol in pediatric and sensitive populations.

• Inhalation Solution & MDI:
• Store at 20°C to 25°C (68°F to 77°F).
• Protect from light and moisture.
• Do not freeze.
• Keep canisters away from heat or open flame.
• Oral Syrup/Tablets:
• Store below 30°C.
• Keep container tightly closed in a dry place.
• Protect from light.