Dimetapp

**Semantic type:** Pharmacologic Substance

**Definition:** A commercial combination preparation, by Wyeth, containing brompheniramine maleate and phenylpropanolamine hydrochloride, with antihistaminergic and vasoconstrictive properties. Brompheniramine maleate, a propylamine antihistamine binds to and blocks H1 receptors thereby preventing the actions of histamine. Phenylpropanolamine hydrochloride is a decongestant that causes constriction of blood vessels mediated through its alpha-adrenergic signaling, thereby reducing blood flow and improving nasal air flow. Dimetapp is used to relieve nasal congestion and to treat rhinitis.