Non sedating antihistamines for allergic rhinitis
The second-generation antihistamines are nonsedating in most patients and are preferred as first-line therapy.
Few adverse effects are reported (cetirizine may cause drowsiness in as many as 10% of patients); therefore, many specialists prefer the use of second-generation agents for allergic rhinitis.
Regular use of an intranasal steroid spray may be more appropriate for patients with chronic symptoms.
Daily use of an antihistamine, decongestant, or both can be considered either instead of or in addition to nasal steroids.
They compete with histamine for histamine receptor type 1 (H1) receptor sites in the blood vessels, GI tract, and respiratory tract, which, in turn, inhibits physiologic effects that histamine normally induces at the H1 receptor sites.Competes with histamine on H1-receptor sites on effector cells in blood vessels and respiratory tract.For symptomatic relief of symptoms caused by release of histamine in allergic reactions. May suppress histamine activity in subcortical region of CNS.Competes with histamine for H1 receptors in GI tract, blood vessels, and respiratory tract, reducing hypersensitivity reactions. Bedtime dosing may be useful if sedation is a problem. Second-generation agent with a rate of sedation not significantly different from that of placebo.
Competes with histamine for H1 receptors in GI tract, blood vessels, and respiratory tract, reducing hypersensitivity reactions. Pseudoephedrine stimulates vasoconstriction by directly activating alpha-adrenergic receptors of the respiratory mucosa.
They can be used prn, but adverse effects may limit their usefulness when taken on a daily basis.