Chapter 37 Respiratory Drugs 2

Question 1

ß Agonists (Sympathomimetic Bronchodilators)

Answer 1

• Salbutamol (Airomir, Ventolin)
• Others include isoproterenol, epinephrine, ephedrine
• Dilate airways by stimulating ß2 adrenergic receptors located throughout the lungs (increased levels of cAMP cause bronchial smooth muscles to relax resulting in bronchodilation & increased airflow)
• May also have dilating effect on peripheral vasculature causing decreased diastolic pressure
• ß2 facilitates K+ shift into cells from blood resulting in temporary decrease in serum K+
• Non-selective ß agonists will also produce vasoconstriction which reduces edema or swelling of mucous membranes; cardiovascular effects (increase HR and contraction)
• Causes relief of severe bronchospasm associated with acute exacerbations of asthma and chronic bronchitis
• Nonselective ß & α receptor agonists such as epinephrine will be used to treat shock and hypotension as well as hyperkalemia related to kidney failure

Question 2

B Agonists adverse effects and interactions

Answer 2

• Adverse effects include tremor, hypertension or hypotension, vascular headache (B2 specifically). Also insomnia, restlessness, anorexia, heart stimulation , hyperglycemia, tremor, vascular headache
• Overdose management may include use of a ß blocker
• Interactions include Non-selective ß blocker + ß agonist bronchodilator will antagonizes or render ineffective bronchodilation, ß agonist + MAOIs can cause hypertension, and Xanthines and digoxin used concurrently increase risk of cardiac toxicity and reduced digoxin level

Question 3

Antileukotrines

Answer 3

• montelukast sodium (Singulair)
• Prevent leukotrienes from attaching to receptors located on circulating immune cells (lymphocytes) and immune cells within the lungs (alveolar macrophages)
• Reduction of leukotriene synthesis or action results in smooth muscle relaxation of bronchial airways, decreased mucus secretion and reduced vascular permeability (reduced edema)
• Prevents migration of neutrophils and leukocytes to lungs as these cells will cause further inflammatory response in the airways
• Used prophylatic and long term treatment of asthma in adults and children. Also approved for use in allergic rhinitis
• Montelukast is considered safe in children 2yrs and older (improvement seen in about 1 week)
• Not intended for acute asthma attack
• Recommended to take in the evenings

Question 4

Antileukotrines adverse effects and interactions

Answer 4

• Fewer adverse effects and interactions with montelukast sodium (Singulair)
• Some case reports of Churg-Strauss syndrome on montelukast: desctruction of blood vessels, subq nodules, large skin plaques and elevated eosinophils
  Interactions
• Phenobarbital decreases montelukast concentrations

Question 5

Corticosteroids

Answer 5

• Fluticasone proprionate (Flovent)
• methylprednisolone (Solu-Medrol) and prednisone are readily used as systemic corticosteroids
• Works to reduce inflammation and enhance activity of ß agonists. Inhibit the inflammatory response by all WBCs but particularly well on mast cells and alveolar macrophages in localized respiratory tract tissues
• Nonspecific anti-inflammatory: Stabilize cell membranes from releasing harmful bronchoconstricting substances (histamine, slow-reacting substance of anaphylaxis or SRS-A)
• Control of inflammatory response in bronchospastic disorders such as asthma and COPD
• Often used concurrently with ß agonists
• Systemic corticosteroids are generally only used during acute exacerbations (IV or oral)

Question 6

Corticosteroids contraindications, adverse effects, and interactions

Answer 6

• Contraindicated in patients who are hypersensitive to glucocorticoids, patients who have tested positive for Candida albicans or systemic fungal infections
• Adverse Effects include pharyngeal irritation, dry mouth, oral fungal infections, insomnia, nervousness, seizures, brittle skin, bone loss, osteoporosis, bone growth suppression in children especially with larger doses
• Systemic steroids may also cause adrenal insufficiency (Addison crisis), immune suppression, fluid and electrolyte disturbances endocrine effects
• Slow tapering of systemic drugs are required to avoid adrenal gland failure and ensuing Addison crisis
  Interactions
• Interactions are more likely with systemic versus inhaled corticosteroids
• Interactions include increased glucose levels resulting in increased dose of antidiabetic drugs. raised blood levels of immunosuppressants, reduced clearance of steroids when using antifungal itraconazole and increased clearance when using phenytoin, phenobarbital and rifampin

Question 7

Anticholinergics

Answer 7

• Ipratropium bromide (Atrovent)
• Work by blocking Ach receptors on bronchial tree to prevent bronchoconstriction, indirectly causing airway dilation
• Used for the prevention of bronchospasm associated with chronic bronchitis or emphysema (maintenance effect). Not for management of acute bronchospasms

Question 8

Anticholinergics contraindications, adverse effects, and interactions

Answer 8

Contraindications include an allergy to atropine
Adverse Effects include dry mouth or throat, nasal congestion, heart palpitations, GI distress, headache, coughing and anxiety
Interactions include possible additive effects when used with other anticholinergics