Nitrogen-containing heterocycles exhibit a diverse range of biological activities and are widely explored and utilized by the pharmaceutical industry for drug discovery. There are a lot of synthesized N-Containing heterocyclic compounds that showed antiallergic/antihistamine activities. A series of imidazole derivatives (Such as cimetidine), benzimidazole derivatives (Such as Astemizole, Bilastine, Emedastine,
Mizolastine, and Clemizole), and 2-methylpropanamide and benzamide derivatives of carboxyterfenadine are synthesized and evaluated as H1 antihistamine activity. Quinazolinone derivatives, pteridinones related compounds, and piperidine derivatives (such as Fexofenadine) also have strong antihistamine activity with a low sedative effect. Antihistaminic activity of the synthesized compounds was studied on the
histamine-induced contractions of guinea-pig ileum tissues.
Keywords: Anti-allergic, Antihistaminic, Drugs, Heterocycles, Nitrogen.
