Which class does Chlorpheniramine maleate belong to?

Chlorpheniramine maleate is classified as a first-generation antihistamine. This designation is primarily due to its ability to cross the blood-brain barrier, leading to central nervous system effects, including sedation. First-generation antihistamines, such as chlorpheniramine, are known for their anticholinergic properties, which can help relieve allergic symptoms but also come with side effects such as drowsiness, dry mouth, and blurred vision.

These characteristics distinguish first-generation antihistamines from second-generation antihistamines, which typically cause less sedation as they are more selective for peripheral H1 receptors and less likely to penetrate the central nervous system. Non-sedating antihistamines are often associated with this group as well. Topical antihistamines refer to those applied directly to the site of action, and chlorpheniramine does not fit this category since it is taken orally. Therefore, the classification of chlorpheniramine as a first-generation antihistamine is based on its pharmacological properties and the historical classification of antihistamines.