[ Read the disclaimer | Adults: Allergic rhinitis, seasonal/perennial: 5 mg po qd. In patients with liver or renal impairment, a starting dose of one 5 mg tablet every other day is recommended based on pharmacokinetic data.
Mechanism of Action Desloratadine is a long-acting tricyclic histamine antagonist with selective H1-receptor histamine antagonist activity.
Histamine is a natural substance, one of the important inflammatory mediators produced in certain cells in the body.(20) When introduced into the nose, histamine causes dilatation and leakage of blood vessels.Dextromethorphan may be beneficial in adults with cough, but its effectiveness has not been demonstrated in children and adolescents.Codeine has not been shown to effectively treat cough caused by the common cold.These are alpha-agonists which on topical application as dilute solution (0.05-0.1%) produce local vasoconstriction.
Regular use of these agents for long periods should be avoided because mucosal ciliary function is impaired: atrophic rhinitis and anosmia can occur due to persistent vasoconstriction.
Decongestant nasal sprays and eye drops often contain oxymetazoline and are used for topical decongestion.
Pseudoephedrine acts indirectly on the adrenergic receptor system, whereas phenylephrine and oxymetazoline are direct agonists.
Antihistamines and combination antihistamine/decongestant therapies can modestly improve symptoms in adults; however, the benefits must be weighed against potential side effects.
Newer nonsedating antihistamines are ineffective against cough.
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