Clonidine is a centrally acting α2 adrenergic agonist and imidazoline receptor agonist used to treat high blood pressure, attention deficit hyperactivity disorder, anxiety disorders, tic disorders, withdrawal (from either alcohol, opioids, or smoking), migraine, menopausal flushing, diarrhea, and certain pain conditions. Clonidine treats high blood pressure by stimulating α2 receptors in the brain, which decreases peripheral vascular resistance, lowering blood pressure. It has specificity towards the presynaptic α2 receptors in the vasomotor center in the brainstem. This binding decreases presynaptic calcium levels, thus inhibiting the release of norepinephrine (NE). It has also been proposed that the antihypertensive effect of clonidine is due to agonism on the I1 receptor (imidazoline receptor), which mediates the sympatho-inhibitory actions of imidazolines to lower blood pressure. Clonidines mechanism of action in the treatment of ADHD is to increase noradrenergic tone in the prefrontal cortex (PFC) directly by binding to postsynaptic α2A adrenergic receptors and indirectly by increasing norepinephrine input from the locus coeruleus. Clonidine indicated in the treatment of hypertension. Clonidine hydrochloride tablets may be employed alone or concomitantly with other antihypertensive agents. The US Food and Drug Administration (FDA) has approved clonidine for the treatment of attention deficit hyperactivity disorder (ADHD), under the trade name of Kapvay alone or with stimulants in 2010, for pediatric patients aged 6–17 years.

(S)-Carteolol is an enantiomer of the racemic drug carteolol, that is used to treat glaucoma. (S) isomer is a partial agonist with the high affinity to the beta-adrenoceptors. It was shown, that in the treatment of glaucoma, the therapeutic advantage of the R(+)-isomers is similar to the S(-)-isomers and there is no stereo-selectivity between the two enantiomers.

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.

Clonidine is a centrally acting α2 adrenergic agonist and imidazoline receptor agonist used to treat high blood pressure, attention deficit hyperactivity disorder, anxiety disorders, tic disorders, withdrawal (from either alcohol, opioids, or smoking), migraine, menopausal flushing, diarrhea, and certain pain conditions. Clonidine treats high blood pressure by stimulating α2 receptors in the brain, which decreases peripheral vascular resistance, lowering blood pressure. It has specificity towards the presynaptic α2 receptors in the vasomotor center in the brainstem. This binding decreases presynaptic calcium levels, thus inhibiting the release of norepinephrine (NE). It has also been proposed that the antihypertensive effect of clonidine is due to agonism on the I1 receptor (imidazoline receptor), which mediates the sympatho-inhibitory actions of imidazolines to lower blood pressure. Clonidines mechanism of action in the treatment of ADHD is to increase noradrenergic tone in the prefrontal cortex (PFC) directly by binding to postsynaptic α2A adrenergic receptors and indirectly by increasing norepinephrine input from the locus coeruleus. Clonidine indicated in the treatment of hypertension. Clonidine hydrochloride tablets may be employed alone or concomitantly with other antihypertensive agents. The US Food and Drug Administration (FDA) has approved clonidine for the treatment of attention deficit hyperactivity disorder (ADHD), under the trade name of Kapvay alone or with stimulants in 2010, for pediatric patients aged 6–17 years.

(S)-Carteolol is an enantiomer of the racemic drug carteolol, that is used to treat glaucoma. (S) isomer is a partial agonist with the high affinity to the beta-adrenoceptors. It was shown, that in the treatment of glaucoma, the therapeutic advantage of the R(+)-isomers is similar to the S(-)-isomers and there is no stereo-selectivity between the two enantiomers.

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.