COPD is defined as airflow limitation that is not fully reversible. the airflow limitation is due to an abnormal inflammatory response to noxious particles in the airway. it presents clinically as a combination of chronic bronchitis and emphysema.
therapy for COPD depends on the severity, which is graded mild/moderate/severe based on FEV1 criteria:
COPD is considered irreversible, and hence incurable. because of this, therapy is symptomatic.
bronchodilators
- short-acting B2-adrenergic agonists (albuterol)
- long-acting B2-adrenergic agonists (salmeterol)
- muscarinic receptor antagonists (ipratropium)
- theophylline
B2-adrenergic agonist bronchodilators take advantage of the selective functionality of B2-adrenergic receptors for bronchial smooth muscle relaxation:
B2-adrenergic agonist toxicity is due to its lesser affinity for B1-adrenergic receptors. the main adverse effect is tachycardia. also, they are known to cause hyperglycemia due to beta-adrenergic receptor action on liver (remember that epinephrine mobilizes glucose).
muscarinic receptor antagonists block the cholinergic bronchoconstrictive tone in the lungs. as a non-selective agent, it can only be delivered by inhalation and does not diffuse into the blood. this limits side-effects to the oronasal cavity. since muscarinic receptors mediate secretions from endocrine and exocrine glands, side-effects are limited to coughs, nasal dryness, and irritation.
theophylline is no longer used for first line bronchodilation. it is an adenosine receptor antagonist, but may also have non-specific inhibition of PDE isozymes (resulting in sustained cAMP levels). its effect is also bronchial smooth muscle relaxation. side-effects are generally non-specific: nausea, vomiting, anxiety, insomnia, and tachycardia. think caffeine-like.
glucocorticosteroids
- fluticasone
the use of anti-inflammatory corticoisteroids is considered controversial – despite the underlying inflammatory nature of COPD’s progression, no study has proven the efficacy of corticosteroids in improving outcome for patients. because of its limited delivery through inhalation, side-effects include oral candidiasis, nasal and throat irritation.
antibiotics
given in severe cases of purulent secretions.
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