Pharmacodynamics<unk>  is a sympathomimetic that selectively agonizes α1 and, partially, α2 adrenergic receptors. Since vascular beds widely express α1 receptors, the action of<unk>  results in vasoconstriction. In addition, the local application of the drug also results in vasoconstriction due to its action on endothelial postsynaptic α2 receptors; systemic application of α2 agonists, in contrast, causes vasodilation because of centrally-mediated inhibition of sympathetic tone via presynaptic α2 receptors. Vasoconstriction of vessels results in relief of nasal congestion in two ways: first, it increases the diameter of the airway lumen; second, it reduces fluid exudation from postcapillary venules. It can reduce nasal airway resistance (NAR) up to 35.7% and reduce nasal mucosal blood flow up to 50%. Pharmacokinetics Imidazolines are sympathomimetic agents, with primary effects on α adrenergic receptors and little if any effect on β adrenergic receptors.<unk>  is readily absorbed orally. Effects on α receptors from systemically absorbed<unk>  hydrochloride may persist for up to 7 hours after a single dose. The elimination half-life in humans is 5–8 hours. It is excreted unchanged both by the kidneys (30%) and in feces (10%).
Oxymetazoline
Xylometazoline
Methylergometrine
Erythrocrine
Terbutaline
Terazosin
Papaverine
Dihydroergotamine