Moxonidine Hydrochloride is a selective agonist at the imidazolinereceptor subtype 1, used as antihypertensive agent. Target: I1-R Moxonidine Hydrochloride is a centrally acting antihypertensive agent. Mixed Nischarin (I1 imidazolinereceptor) and α2-AR (adrenergic) agonist; displays 40-fold higher affinity for I1 receptors versus α2-adrenoceptors. Moxonidine reduced stimulated NE overflow (log EC50: -6.15 + - 0.14). AGN192403, a selective ligand at I1-R, had no influence on the dose-response curve of moxonidine (log EC50: -6.01 + - 0.25). The hypotensive and bradycardic actions of moxonidine but not clonidine are mediated through imidazolinereceptors and are dependent on intact noradrenergic pathways within the RVLM. Furthermore, the noradrenergic innervation may be associated with a 42 kDa imidazolinereceptor protein.
Cirazoline (free base) is a full agonist at the α1A adrenergic receptor, a partial agonist at both the α1B and α1D adrenergic receptors, and a nonselective antagonist to the α₂ adrenergic receptor. It is believed that this combination of properties could make cirazoline an effective vasoconstricting agent.