Drugs Used in Upper Respiratory Disorders: Overview

Antihistamines are H1 receptor antagonists that block histamine from binding to H1 receptors on cells. By preventing histamine attachment, they effectively reduce allergic symptoms such as runny nose and itching. This mechanism provides relief for individuals suffering from allergic rhinitis and other allergic upper respiratory conditions.

Systemic decongestants like Sudafed are taken orally and cause vasoconstriction throughout the body, but they increase blood pressure and heart rate. Nasal decongestants like Afrin are sprayed directly into nostrils and work locally on nasal blood vessels. While nasal decongestants are effective short-term, prolonged use can worsen congestion.

Intranasal steroids inhibit mast cell and white blood cell responses, reducing inflammatory mediator production and decreasing vascular permeability. These actions directly reduce inflammation in the nasal passages and help alleviate symptoms of allergic rhinitis, improving breathing and overall comfort for patients.

Antitussives suppress coughing by depressing the cough center in the medulla or reducing sensory nerve responsiveness. Expectorants work differently by hydrating and thinning respiratory secretions, making mucus easier to expel. While antitussives relieve cough discomfort, expectorants help clear airways by facilitating mucus clearance.

Mucolytics are chemicals or proteins that directly break down mucus by reducing its thickness and facilitating clearance. Expectorants hydrate and thin secretions to aid expulsion. Both address excessive mucus production, but mucolytics chemically alter mucus structure while expectorants modify secretion consistency.

Decongestants address nasal congestion by causing vasoconstriction of small blood vessels in nasal membranes, opening clogged passages and promoting sinus drainage. They are effective for managing colds, sinusitis, and rhinitis. Both systemic and nasal decongestants provide this benefit, though with different side effect profiles.

Mast cells and white blood cells are key players in the immune response that triggers allergic rhinitis. Intranasal steroids inhibit their responses and reduce inflammatory mediator production, effectively decreasing inflammation and alleviating allergy symptoms. This targeted immune suppression provides relief without affecting systemic immune function.