STUDIES ON THE RECEPTOR PROFILE OF BISOPROLOL

  • 1 January 1986
    • journal article
    • research article
    • Vol. 36-1  (2) , 197-200
Abstract
The in vitro binding affinity of (.+-.)-1-[4-(2-isopropoxyethoxymethyl)-phenoxy]-3-isopropylamino-2-propranol hemifumarate (bisoprolol, EMD 33 512) to .beta.1-, .beta.2-.alpha.1-, .alpha.2, D1-, D2-, 5-HT2- and muscarinic cholinergic receptors of rat was compared with that of atenolol, betaxolol and propranolol. Bisoprolol showed a high specific binding affinity to .beta.1-adrenoceptors (heart) and a low specific binding affinity to .beta.2-adrenoceptors (lung). The .beta.1-selectivity of bisoprolol (.beta.2/.beta.1 = 34.7) proved to be higher than that of atenolol (8.7) and betaxolol (12.5). Propranolol (0.59) was non-selective as expected. Bisoprolol and atenolol exhibited no remarkable binding affinity to .alpha.1-, .alpha.2-, D1-, D2-, 5-HT2- and muscarinic cholinergic receptors at concentrations up to 1 .times. 104 mol/l. For betaxolol binding affinities for .alpha.2-, D2- and 5-HT2-receptors were found with IC50 values ranging between 2 .times. 10-5 and 7 .times. 10-5 mol/l. For propranolol binding affinities for .alpha.1-, .alpha.2-, D1-, D2- and 5-HT2-receptors were found with IC50 values ranging between 2 .times. 10-6 and 9 .times. 10-5 mol/l.