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Discover how Cimetidine works as an H2 blocker to reduce stomach acid and treat ulcers GERD and related digestive disorders. Structure of Cimetidine It is a first-generation H₂-receptor antagonist featuring a thiazole ring connected to a dimethylamine side chain and an imidazole moiety. Chemical Formula: C₁₆H₂₄N₄S Mode of Action Cimetidine selectively inhibits H₂ receptors on … Read more

This topic describes how H2 antagonists reduce stomach acid by blocking histamine action and are used to treat ulcers acid reflux and related conditions. Definition H2 Antagonists: H₂ antagonists are a class of drugs that block histamine H₂ receptors located on the parietal cells of the stomach. By inhibiting histamine’s action, these drugs reduce the … Read more

Cromolyn Sodium is a mast cell stabilizer widely used in the treatment of allergic conditions such as asthma, allergic rhinitis, and conjunctivitis. Unlike typical antihistamines, it does not block H₁ receptors directly but works by preventing the release of histamine and other inflammatory mediators from sensitized mast cells. Its unique chemical structure, a polysulfated derivative … Read more

Levocetirizine is the active enantiomer of cetirizine, offering enhanced potency and reduced side effects in the treatment of allergic conditions. Structurally, it retains the piperazine ring seen in cetirizine but provides greater selectivity for peripheral H₁ receptors. Structure of Levocetirizine It is the active enantiomer of Cetirizine, featuring a similar piperazine structure with enhanced selectivity. … Read more

Loratadine is a second-generation, non-sedating H₁-antihistamine commonly used to manage allergic rhinitis, urticaria, and seasonal allergic reactions. It features a tricyclic structure that enhances peripheral selectivity and reduces central nervous system penetration, resulting in minimal sedation. It works by selectively blocking peripheral H₁ receptors, providing long-lasting relief from histamine-induced symptoms such as sneezing, itching, and … Read more

Cetirizine is a second-generation H₁-antihistamine derived from hydroxyzine, widely used for managing allergic rhinitis, chronic urticaria, and seasonal allergies. Its structure includes a piperazine ring substituted with a carboxylic acid group and an aromatic ring, contributing to its peripheral selectivity. By blocking H₁ receptors without significant CNS penetration, it effectively relieves histamine-mediated symptoms with minimal … Read more

Astemizole is a second-generation H₁-antihistamine known for its non-sedating action due to limited blood-brain barrier penetration. Structurally, it features a benzoxazole ring fused to a piperazine moiety, contributing to its high receptor selectivity. It effectively treats allergic rhinitis, urticaria, and chronic idiopathic urticaria by blocking H₁ receptors and exhibiting mild anti-inflammatory properties without significant central … Read more