Betaxolol is a competitive, beta(1)-selective (cardioselective) adrenergic antagonist. Betaxolol is used to treat hypertension, arrhythmias, coronary heart disease, glaucoma, and is also used to reduce non-fatal cardiac events in patients with heart failure. (R)-Betaxolol (Dextrobetaxolol) is the R-isomer of Betaxolol (B328000), a cardioselective β1-adrenergic blocker. It is also an antihypertensive and antiglaucoma agent. Dextrobetaxolol had a much weaker affinity at both b1 and b2 receptors than levobetaxolol. Levobetaxolol (Kb=6 nM at b1 and Kb=39 nM at b2 receptors) more potently inhibited functional activities in cells expressing human recombinant b1 and b2 receptors than dextrobetaxolol (Kb=350 and 278 nM, respectively). Likewise, levobetaxolol was a more potent antagonist in isolated tissues than dextrobetaxolol. In functional assays in cultured human NPE cells levobetaxolol (Ki =16.4 nM) was a potent antagonist of isoproterenol-induced cAMP production with dextrobetaxolol (Ki =2.9 uM) being considerably weaker than the latter antagonist. In ocular hypertensive cynomolgus monkeys, levobetaxolol was more effective at reducing IOP than dextrobetaxolol. The results of the study of the pharmacokinetic behavior of the R and S enantiomers of betaxolol following iv and oral administration of the racemate to healthy male subjects failed to reveal any important difference between the pharmacokinetics of the R and S enantiomer of betaxolol. Thus, the pharmacokinetic behavior of racemic betaxolol accurately reflects the behavior of betaxolol enantiomers in this subject group.