SABAs and LABAs: Asthma Medications

Short-Acting Beta-2 Agonists (SABAs)

• Albuterol (ProAir®, Ventolin®, Proventil®): Used for quick relief of asthma symptoms and exercise-induced bronchospasm.

• Mechanism: Stimulates beta-2 adrenergic receptors in bronchial smooth muscle, causing bronchodilation.

• Pharmacokinetics:

  • Onset: 5-15 minutes
  • Duration: 4-6 hours
  • Metabolism: Liver; excretion in urine

• Use: PRN (as needed). Frequent use (>2 days/week) may indicate poor asthma control.

• Side effects: Tremors, tachycardia, hypokalemia.

• Levalbuterol (Xopenex®): Rescue inhaler for asthma and COPD. Has fewer beta-1 effects.

• Mechanism: Selectively stimulates beta-2 receptors, leading to bronchodilation (R-enantiomer of albuterol).

• Pharmacokinetics:

  • Onset: 5-10 minutes
  • Duration: 3-6 hours
  • Metabolism: Hepatic; excretion in urine

• Side effects: Less tachycardia than albuterol.

Long-Acting Beta-2 Agonists (LABAs)

• Salmeterol (Serevent®): Maintenance therapy for moderate-to-severe asthma and COPD, always in combination with inhaled corticosteroids (ICS).
• Mechanism: Selectively stimulates beta-2 receptors, prolonging bronchodilation.
• Pharmacokinetics:
  • Onset: 30-60 minutes
  • Duration: 12+ hours
  • Metabolism: Hepatic (CYP3A4)
• Black Box Warning (BBW): Increased risk of asthma-related death if used without inhaled corticosteroids (ICS).

Inhaled Corticosteroids (ICS)

• Fluticasone (Flovent®, Arnuity®): First-line maintenance therapy for persistent asthma.

• Mechanism: Inhibits inflammatory cytokines, reducing airway inflammation.

• Pharmacokinetics:

  • High first-pass effect, low systemic absorption
  • Metabolism: Hepatic (CYP3A4)

• Use: Long-term asthma control

• Side effects: Oral thrush, if patients do not rinse their mouth after use. May take 1-2 weeks for full effect.

• Budesonide (Pulmicort®): Long-term control of asthma and COPD.

• Mechanism: Suppresses airway inflammation by reducing inflammatory cell activity.

• Pharmacokinetics:

  • Onset: Several days to weeks
  • Preferred ICS in pregnancy; available as a nebulizer

• Metabolism: Hepatic (CYP3A4)

Antimuscarinic Agents

• Ipratropium Bromide (Atrovent®): Short-acting (SAMA), used for COPD maintenance therapy and asthma exacerbation, combined with a SABA.
• Mechanism: Blocks muscarinic (M3) receptors to prevent bronchoconstriction.
• Pharmacokinetics:
  • Onset: 15 minutes
  • Duration: 4-6 hours
• Tiotropium (Spiriva®): Long-acting (LAMA), used for maintenance therapy of COPD and severe asthma.
• Mechanism: M3 receptor antagonist reducing bronchoconstriction and mucus secretion.
• Pharmacokinetics:
  • Duration: 24 hours

Leukotriene Receptor Antagonists

• Montelukast (Singulair®): Asthma prophylaxis, allergic rhinitis, Exercise-induced asthma.
• Mechanism: Blocks leukotriene D4 receptors, reducing airway inflammation and bronchoconstriction.
• Pharmacokinetics:
  • Hepatic metabolism (CYP2C9, CYP3A4)
• Black Box Warning (BBW): Neuropsychiatric events (mood changes, aggression).
• Use: Second-line option to inhaled corticosteroids (ICS)

Biologics (Severe Asthma)

• Omalizumab (Xolair®): For severe allergic asthma.

• Mechanism: Binds to IgE, preventing mast cell activation.

• Pharmacokinetics: SC every 2-4 weeks.

• Black Box Warning (BBW): Anaphylaxis risk; patients must be observed after injection

• Mepolizumab (Nucala®): Eosinophilic asthma - targets IL-5.

Phosphodiesterase-4 (PDE-4) Inhibitors

• Roflumilast (Daliresp®): Severe COPD with chronic bronchitis.
• Mechanism: Inhibits PDE-4, reduces inflammation.
• Pharmacokinetics: Oral once daily.
• Side effects: GI distress, weight loss, psychiatric symptoms.

Intranasal Corticosteroids for Allergic Rhinitis

• Fluticasone (Flonase®): for allergic rhinitis,
• Mechanism: Reduces nasal inflammation.
• Pharmacokinetics: Low systemic absorption

Decongestants

• Oxymetazoline (Afrin®): For nasal congestion.
• Mechanism: Alpha-adrenergic agonist, causing nasal vasoconstriction.
• Pharmacokinetics:
  • Onset: Minutes
  • Duration: 12 hours
• Use: Limit use to 3 days to prevent rebound congestion (rhinitis medicamentosa).

Overview of short and long-acting beta-2 agonists. Includes mechanisms, pharmacokinetics, uses, and side effects of albuterol, levalbuterol and salmeterol. Focus on asthma and COPD treatments.