Pseudoephedrine

Pseudoephedrine is a mixed-acting α1-adrenergic agonist with both indirect and direct actions. Pseudoephedrine can directly stimulate α1-adrenergic receptors on vascular smooth muscle in the nasal cavity and upper respiratory mucosa. Through Gq protein coupling, it activates phospholipase Cβ, increases IP3/DAG, raises cytosolic calcium, and activates protein kinase C, resulting in vasoconstriction and reduced mucosal blood flow and tissue edema. Pseudoephedrine can also enter sympathetic nerve terminals and promote the release of norepinephrine stored in vesicles, further enhancing α1 receptor-mediated vasoconstriction.