Chapter 38: Upper Respiratory Disorder Drug Therapy

Upper Respiratory Disorder Drug Therapy establishes a clear framework for treating common upper respiratory infections (URIs) such as the common cold, acute rhinitis, sinusitis, and acute pharyngitis, distinguishing between viral etiologies and bacterial infections like beta-hemolytic streptococci. A significant portion of the text is dedicated to antihistamines (H1 antagonists), explaining how these agents compete for H1 receptor sites to decrease nasopharyngeal secretions and treat allergic rhinitis. The summary contrasts the pharmacodynamics of first-generation antihistamines, such as diphenhydramine—which are associated with significant drowsiness and anticholinergic effects like dry mouth and urinary retention—against second-generation agents like cetirizine, fexofenadine, and loratadine, which offer relief with minimal sedation. The discussion extends to nasal and systemic decongestants, describing how sympathomimetic amines stimulate alpha-adrenergic receptors to induce vasoconstriction and shrink swollen nasal mucous membranes. Crucial safety protocols are outlined regarding the risk of rebound nasal congestion (rhinitis medicamentosa) from overuse of topical sprays like oxymetazoline, as well as the potential for systemic hypertension and dysrhythmias with oral decongestants like pseudoephedrine. Additionally, the chapter covers the use of intranasal glucocorticoids (e.g., fluticasone, mometasone) for their anti-inflammatory benefits, antitussives (both opioid and nonopioid like dextromethorphan) that suppress the cough center in the medulla, and expectorants like guaifenesin that facilitate mucus removal. The content concludes by integrating the nursing process, emphasizing patient assessment for contraindications such as glaucoma and hypertension, and educating patients on hydration and drug safety to prevent adverse interactions with CNS depressants.