Norpropranolol is an active metabolite of the β-adrenergic receptor (β-AR) antagonist propranolol .1,2 It is formed from propranolol by the cytochrome P450 (CYP) isoform CYP1A2.2 Norpropranolol binds to β-ARs (Kd = 42 nM in turkey erythrocytes) and inhibits (-)-isoproterenol-induced activation of adenylate cyclase with a Ki value of 175 nM.1
1.Bilezikian, J.P., Dornfeld, A.M., and Gammon, D.E.Structure-binding-activity analysis of beta-adrenergic amines—I. Binding to the beta receptor and activation of adenylate cyclaseBiochem. Pharmacol.27(10)1445-1454(1978) 2.Masubuchi, Y., Hosokawa, S., Horie, T., et al.Cytochrome P450 isozymes involved in propranolol metabolism in human liver microsomes. The role of CYP2D6 as ring-hydroxylase and CYP1A2 as N-desisopropylaseDrug Metab. Dispos.22(6)909-915(1994)