Bronchodilators Lecture Notes

Overview

• Bronchodilators: Medications that assist breathing by keeping airways dilated.
• Used in obstructive lung diseases like Asthma and Chronic Obstructive Pulmonary Disease (COPD).

Asthma

• Characteristics: Chronic inflammation, asthma exacerbations/attacks.
• Triggers: Viruses, allergens, stress, aspirin, NSAIDs, exercise.
• Symptoms: Dyspnea, wheezing, chest tightness, coughing.
• Mechanism: Reversible bronchial muscle spasms and mucus production.

Chronic Obstructive Pulmonary Disease (COPD)

• Characteristics: Chronic inflammation and fibrosis, often due to smoking.
• Symptoms: Dyspnea, productive cough.
• Types: Includes chronic bronchitis and emphysema.
  • Chronic Bronchitis: Long-term bronchial inflammation.
  • Emphysema: Destruction/enlargement of alveoli.
• Mechanism: Irreversible airway obstruction, air trapped in lungs.

Types of Bronchodilators

1. Beta-2 Agonists

   • Examples: Albuterol, Salmeterol.
   • Forms: Aerosolized, via MDI or nebulizers.
   • Action: Bind to beta-2 adrenergic receptors, promote smooth muscle relaxation.
   • Subtypes:
     • Short-acting (SABAs): e.g., Albuterol for acute relief.
     • Long-acting (LABAs): e.g., Salmeterol with corticosteroids for maintenance.

2. Anticholinergics

   • Examples: Ipratropium, Tiotropium.
   • Forms: Inhalers or nebulizers.
   • Action: Block M3 muscarinic receptors, reduce smooth muscle constriction.
   • Efficacy: Less effective in asthma, preferred in COPD.

3. Methylxanthines

   • Example: Theophylline.
   • Forms: Oral or IV.
   • Action: Inhibit phosphodiesterase, promote muscle relaxation.
   • Use: Less common due to side effects.

Side Effects

• Beta-2 Agonists: Tremors, restlessness, insomnia, tachycardia, palpitations.
  • Use caution in heart, renal disease, hyperthyroidism, diabetes, pregnancy.
• Anticholinergics: Pupil dilation, dry mouth, tachycardia, restlessness.
  • Caution in glaucoma, heart disease, hyperthyroidism.
• Methylxanthines: Insomnia, nausea, vomiting, narrow therapeutic window.
  • Avoid in seizure disorders, heart/renal/liver diseases.

Administration Tips

• Preparation: Assess baseline vital signs and lung sounds.
• Education: Explain purpose, administration method, side effects.
• MDI Use:
  • Demonstrate using a spacer.
  • Steps: Shake canister, attach spacer, exhale, inhale the medication slowly.
  • Advise rinse mouth post-inhalation to avoid oral infections.
• Theophylline:
  • Monitor serum levels for toxicity (>20 mcg/mL).
  • Avoid smoking, caffeine, alcohol.

Post-Administration

• Assess lung sounds, vital signs.
• Monitor for significant changes or adverse effects.
• Evaluate therapeutic effectiveness: decreased dyspnea, improved wheezing, better airway exchange.

Summary

• Bronchodilators dilate airways, improve airflow, used in asthma and COPD.
• Types: Beta-2 agonists, anticholinergics, methylxanthines.
• Important to assess, educate, and monitor patients for effective use and side effects.