A decongestant or nasal decongestant relieves nasal congestion in the upper respiratory tract. These drugs are available in the form of sprays or nasal drops (topical decongestants) or as tablets or capsules usually combined with paracetamol. Other forms of nasal decongestants are steam inhalation and saline nasal drops which provide temporary relief from congestion. Congestion is caused by swelling of the blood vessels inside the nose in response to irritation in case of infection or allergy. Glands in the affected areas start to produce mucus which may trap pathogens. Both the swollen vessels and excess mucus production can block the nose and cause nasal stuffiness. Nasal decongestants work by acting on adrenergic receptors in the nose which constricts the blood vessels as well as reduces inflammation and mucus formation. Some of the agents commonly used in decongestants include pseudoephedrine, phenylephrine, levomethamphetamine, propylhexedrine, synephrine, tetrahydrozoline, naphazoline, oxymetazoline, and xylometazoline.
Pseudoephedrine is used to relieve the symptoms of congestion, but cannot treat the cause of the problem or accelerate recovery. It can be taken as a regular tablet or as a long-acting agent that is released over a 12- or 24- hour period (extended-release). The drug can also be taken in liquid form. Pseudoephedrine can cause vomiting, headache, nausea, vomiting, and restlessness, dizziness, breathing difficulty, abdominal pain, and a fast or irregular heartbeat.
- It should not be given to children aged less than 4 years.
- Pseudoephedrine should not be given to the patient if already taking MAO inhibitors such as selegiline, tranylcypromine, or phenelzine.
- Should be carefully given in patients with glaucoma, high blood pressure, diabetes, thyroid disease, heart disease, or difficulty urinating.
- A large intake of caffeine can increase the adverse side effects of this medication.
Phenylephrine hydrochloride is a nasal decongestant that helps to relieve a blocked nose. It reduces the size of the blood vessels in the nose and sinuses helping you to breathe more easily. Phenylephrine is a sympathomimetic drug, which means that it mimics the actions of epinephrine (commonly known as adrenaline) or norepinephrine. Phenylephrine selectively binds to alpha-1 receptors which cause blood vessels to constrict. The primary side effects are high blood pressure with slow heart rate, reflex bradycardia if given intravenously, prostatic hyperplasia may worsen, phenylephrine is a pregnancy category C drug.
Xylometazoline stimulates adrenergic receptors on the lamina propria of blood vessels in the nose. The decongestant effect is due to the constriction of large veins in the nose which swell up during the inflammation of any infection or allergy of the nose reducing blood flow to engorged, edematous tissue. The standard adult solution strength is 0.1% w/v xylometazoline, and the dose for children under 12 is usually 0.05% every 8-10 h.
Side effects: Rebound congestion, or rhinitis medicamentosa, increases blood pressure, oxymetazoline is category C, indicating risk to the fetus.
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