Trimetoquinol hydrochloride dilates bronchial muscle selectively by stimulating Beta 2-receptors. It is used for the relief of bronchoconstriction associated with bronchitis, asthmatic bronchitis and bronchial asthma. Since the concurrent use of the drug with catecholamines such as Epinephrine and Isoproterenol may induce arrythmia or cardiac arrest in some cases, concurrent use is not recommended. Adverse reactions : Palpitation may occur occasionally, and alteration of blood pressure and precordial pain may appear rarely; headache may occur occasionally; tremor, dizziness, feverish sensation may also be encountered in a rare incidence; occasionally, nausea and anorexia may appear.

Zinterol (MJ-9184-1) is an beta-adregenrgic agonist demostrated activity toward beta1-3 receptors. Oral zinterol caused a fast-appearing and long-lasting bronchodilator effect in patients with with stable chronic obstructive lung disease, however it seems development of zinterol was discontitued.

Dilevalol, the RR-stereoisomer of labetalol, is a non-cardioselective β-adrenoceptor antagonist with substantial partial β2-agonist and negligible α1-blocking activity. Reduction in blood pressure during dilevalol administration is associated with peripheral vasodilatation, and heart rate remains essentially unchanged. Following oral administration, dilevalol is completely absorbed. Once-daily administration is possible, due to a long elimination half-life. In vitro and in vivo animal studies and results obtained in humans reveal that dilevalol is a nonselective blocker of β1- and β2-adrenoceptors, with a similar potency to propranolol, but has negligible antagonistic activity at α1-receptors. Dilevalol, the R,R′ stereoisomer, makes up 25% of racemic labetalol, the drug, approved by FDA for the treatment of hypertension. The relaxing potency of dilevalol was approximately 4.7 times more potent than that of labetalol. Dilevalol markedly reduced the diastolic blood pressure with only a slight increase of heart rate In pithed rats, while isoproterenol and pindolol caused moderate to marked positive chronotropic effects in proportion to their hypotensive effects. These results suggest that dilevalol has more potent ISA than labetalol. In contrast to labetalol, dilevalol possesses little, if any, alpha-adrenergic blocking activity. The compound is 3 to 10 times less potent than labetalol at α1-adrenergic receptors under a variety of experimental conditions. Moreover, it is 300- to 1000-fold less potent at alpha1-adrenergic receptors compared with β1-adrenergic receptors. The pA2 values for dilevalol as an α antagonist range from 5.9 to 6.4. Because maximal plasma concentrations of the drug after administration of a 400-mg dose are approximately 0.5 pmol, it is doubtful that alpha blockade is involved in the antihypertensive response to dilevalol in humans.

Ractopamine hydrochloride, a beta-adrenoceptor agonist, is a phenethanolamine salt approved for use as a feed additive. Recently published studies indicate that the RR-isomer (butopamine) is the stereoisomer with the most activity at the beta-adrenoceptor. Butopamine was shown to be a non-selective ligand at the beta1 and beta2-adrenoceptors, but signal transduction is more efficiently coupled through the b2-adrenoceptor than the beta1 adrenoceptor. Therefore, the RR-isomer of ractopamine is considered to be a full agonist at the beta2-adrenoceptor and a partial agonist at the beta1¬adrenoceptor. These results are consistent with the pharmacological characterization of racemic ractopamine in isolated cardiac (atria) and smooth muscle (costo-uterine, vas deferens, trachea), which shows a maximal response at beta2- and a submaximal response at beta1¬adrenoceptors when compared with the full beta1 and beta2-adrenoceptor agonist isoproterenol. Butopamine is chemically similar to dobutamine but, unlike dobutamine, it is not a catecholamine. Butopamine induces a positive inotropic response in patients with congestive heart failure but for equal increments in cardiac output, butopamine increases heart rate more than dobutamine. Butopamine inproved cardiac performance in patients with ventricular dysfunction and congestive heart failure. Butopamine was prepared by Tuttle et al (unpublished data) and has a structure similar to dobutamine. This compound is refractory to the action of catechol-O-methyl transferase and thus it is orally active and has a longlasting action. Clinical findings in acute heart failure cases have been reported by Thompson et al. Intravenous administration produced an increase in the cardiac index and heart rate and shortening of systolic time intervals. A few patients experienced ventricular ectopy, especially with the higher doses used. No data pertaining to oral administration are available.

Landiolol (Onoact) is an intravenously administered, ultra short-acting β1-blocker with an elimination half-life of 3-4 min and ≈8-fold greater cardioselectivity than esmolol in vitro. It is approved in Japan for the treatment of intraoperative and postoperative tachyarrhythmias, but in clinical practice is also used to prevent postoperative tachyarrhythmias, such as atrial fibrillation after coronary artery bypass grafting. Randomized controlled trials in patients undergoing open-heart surgery demonstrated that various dosages of landiolol (0.0005-0.04 mg/kg/min) [0.5-40 μg/kg/min] were more effective than diltiazem in converting postoperative atrial fibrillation to normal sinus rhythm during the first 8 h after surgery, and were more effective than placebo (or no landiolol) in preventing the development of atrial fibrillation during the first week after surgery (primary efficacy endpoints). Landiolol was generally well tolerated in clinical trials, with a relatively low risk of hypotension and bradycardia, although routine monitoring of cardiac function during landiolol administration is important. In general, adverse events such as reduced blood pressure resolve quickly after discontinuation of landiolol. Thus, as an ultra short-acting β1-blocker with a rapid onset of action and readily titratable and rapidly reversible effects, landiolol represents an important agent for the management of intraoperative and postoperative tachyarrhythmias.

Nebivolol is a competitive and highly selective beta-1 receptor antagonist with mild vasodilating properties, possibly due to an interaction with the L-arginine/nitric oxide pathway. In preclinical studies, nebivolol has been shown to induce endothelium-dependent arterial relaxation in a dose dependent manner, by stimulation of the release of endothelial nitric oxide. Nitric oxide acts to relax vascular smooth muscle cells and inhibits platelet aggregation and adhesion. Activation of β1-receptors by epinephrine increases the heart rate and the blood pressure, and the heart consumes more oxygen. Nebivolol blocks these receptors which reverses the effects of epinephrine, lowering the heart rate and blood pressure. In addition, beta blockers prevent the release of renin, which is a hormone produced by the kidneys which leads to constriction of blood vessels. At high enough concentrations, this drug may also bind beta 2 receptors. Marketed under the brand name BYSTOLIC, Nebivolol is indicated for the treatment of hypertension, to lower blood pressure. Lowering blood pressure reduces the risk of fatal and nonfatal cardiovascular events, primarily strokes and myocardial infarctions.

Nebivolol is a competitive and highly selective beta-1 receptor antagonist with mild vasodilating properties, possibly due to an interaction with the L-arginine/nitric oxide pathway. In preclinical studies, nebivolol has been shown to induce endothelium-dependent arterial relaxation in a dose dependent manner, by stimulation of the release of endothelial nitric oxide. Nitric oxide acts to relax vascular smooth muscle cells and inhibits platelet aggregation and adhesion. Activation of β1-receptors by epinephrine increases the heart rate and the blood pressure, and the heart consumes more oxygen. Nebivolol blocks these receptors which reverses the effects of epinephrine, lowering the heart rate and blood pressure. In addition, beta blockers prevent the release of renin, which is a hormone produced by the kidneys which leads to constriction of blood vessels. At high enough concentrations, this drug may also bind beta 2 receptors. Marketed under the brand name BYSTOLIC, Nebivolol is indicated for the treatment of hypertension, to lower blood pressure. Lowering blood pressure reduces the risk of fatal and nonfatal cardiovascular events, primarily strokes and myocardial infarctions.

Bisoprolol is a cardioselective beta1-adrenergic blocking agent. It lower the heart rate and blood pressure and may be used to reduce workload on the heart and hence oxygen demands. This results in a reduction of heart rate, cardiac output, systolic and diastolic blood pressure, and possibly reflex orthostatic hypotension. Bisoprolol can be used to treat cardiovascular diseases such as hypertension, coronary heart disease, arrhythmias, ischemic heart diseases, and myocardial infarction after the acute event. General side effects are: fatigue, asthenia, chest pain, malaise, edema, weight gain, angioedema. Concurrent use of rifampin increases the metabolic clearance of bisoprolol fumarate, shortening its elimination half-life.

Bisoprolol is a cardioselective beta1-adrenergic blocking agent. It lower the heart rate and blood pressure and may be used to reduce workload on the heart and hence oxygen demands. This results in a reduction of heart rate, cardiac output, systolic and diastolic blood pressure, and possibly reflex orthostatic hypotension. Bisoprolol can be used to treat cardiovascular diseases such as hypertension, coronary heart disease, arrhythmias, ischemic heart diseases, and myocardial infarction after the acute event. General side effects are: fatigue, asthenia, chest pain, malaise, edema, weight gain, angioedema. Concurrent use of rifampin increases the metabolic clearance of bisoprolol fumarate, shortening its elimination half-life.

Sotalol has both beta-adrenoreceptor blocking and cardiac action potential duration prolongation antiarrhythmic properties. Sotalol inhibits response to adrenergic stimuli by competitively blocking β1-adrenergic receptors within the myocardium and β2-adrenergic receptors within bronchial and vascular smooth muscle. It is FDA approved for the treatment of ventricular arrhythmias, symptomatic atrial fibtillation, symptomatic atriall flutter. Common adverse reactions include bradyarrhythmia, chest pain, lightheadedness, palpitations, rash, nausea, dizziness, headache, dyspnea, fatigue. Proarrhythmic events were more common in sotalol treated patients also receiving digoxin. Sotalol should be administered with caution in conjunction with calcium blocking drugs because of possible additive effects on atrioventricular conduction or ventricular function. Patients treated with sotalol plus a catecholamine depletor should therefore be closely monitored for evidence of hypotension and/or marked bradycardia which may produce syncope.