Introduction
Nasal decongestants are medicines used to relieve a blocked or stuffy nose. Nasal congestion occurs when the blood vessels in the nasal lining become swollen due to inflammation. Decongestants work by causing local vasoconstriction, which reduces swelling and opens the nasal passages. They provide quick relief in colds, sinusitis and allergic rhinitis.
Mechanism of Action
Most nasal decongestants are alpha adrenergic agonists. When applied topically in low concentrations (0.05–0.1%), they stimulate alpha receptors on the blood vessels of the nasal mucosa. This leads to:
- Constriction of blood vessels
- Reduced swelling of nasal membranes
- Improved air passage
Common Nasal Decongestants
The major drugs used as nasal decongestants include:
- Imidazoline derivatives: Naphazoline, Xylometazoline, Oxymetazoline
- Pseudoephedrine
- Phenylpropanolamine (banned in India)
Naphazoline
Naphazoline is a sympathomimetic agent with strong alpha-adrenergic activity. It acts on alpha-1 receptors (Gq type) present on vascular smooth muscles of the nasal mucosa. By activating these receptors, it increases intracellular calcium and causes vasoconstriction, leading to rapid reduction of swelling.
Uses
- Quick relief of nasal congestion
- Used in common cold, sinus congestion and allergic rhinitis
Adverse Drug Reactions (ADRs)
- Hypertension
- Cardiac arrhythmias
Pseudoephedrine
Pseudoephedrine is an oral sympathomimetic drug widely used for nasal and sinus congestion. It shrinks the swollen blood vessels in the nasal mucosa and helps relieve stuffiness.
Uses
- Nasal congestion due to common cold
- Hay fever and allergic rhinitis
- Sinus congestion and sinusitis
Adverse Effects
- Nervousness
- Dizziness
- Insomnia
- Excitability
- Stomach discomfort
Phenylpropanolamine
Phenylpropanolamine is a sympathomimetic drug that acts on both alpha and beta adrenergic receptors. Due to serious safety concerns, especially risk of stroke, it was banned in India in 2011. It remains available in a few European countries.
Important Notes on Nasal Decongestants
- They provide symptom relief only and do not treat the underlying cause.
- Topical nasal decongestants should not be used for more than 3–5 days to avoid rebound congestion (rhinitis medicamentosa).
- Use cautiously in patients with hypertension, heart disease or hyperthyroidism.
Detailed Notes:
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