What are the classification the histamine H1 receptors antagonist?
There are several classifications of histamine H1 receptor antagonists, including:
1. First-generation antihistamines: These antihistamines are sedating and are often used for their sedative effects in addition to their antihistaminic properties. Examples include diphenhydramine, chlorpheniramine, and promethazine.
2. Second-generation antihistamines: These antihistamines are non-sedating and are preferred for daytime use due to their reduced sedative effects. Examples include loratadine, cetirizine, and fexofenadine.
3. Selective antihistamines: These antihistamines selectively target the H1 receptor and have minimal or no affinity for other receptors, reducing the risk of side effects. Examples include levocetirizine and desloratadine.
4. Dual-action antihistamines: These antihistamines not only block the H1 receptor but also have additional properties, such as anti-inflammatory effects or mast cell stabilization. Examples include azelastine and ketotifen.
5. Combination antihistamines: These antihistamines contain a combination of an H1 receptor antagonist and another medication, such as a decongestant or a corticosteroid. Examples include cetirizine/pseudoephedrine and fluticasone/azelastine.