Antihistamine

An antihistamine is a drug which serves to reduce or eliminate effects mediated by histamine, an endogenous chemical mediator released during allergic reactions, through action at the histamine receptor. Only agents where the main therapeutic effect is mediated by negative modulation of histamine receptors are termed antihistamines - other agents may have antihistaminergic action but are not true antihistamines.

Third-generation H₁-receptor antagonists

These are the active enantiomer (levocetirizine, desloratadine) or metabolite (fexofenadine) derivatives of second-generation drugs intended to have increased efficacy with fewer adverse drug reactions. Indeed, fexofenadine is associated with a decreased risk of cardiac arrhythmia compared to terfenadine. However, there is little evidence for any advantage of levocetirizine or desloratadine, compared to cetirizine or loratadine respectively.

Related Topics:
Adverse drug reaction - Cardiac arrhythmia

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Systemic

• levocetirizine
• desloratadine
• fexofenadine