Nadolol is a nonselective beta-adrenergic receptor antagonist with a long half-life, and is structurally similar to propranolol. Clinical pharmacology studies have demonstrated beta-blocking activity by showing (1) reduction in heart rate and cardiac output at rest and on exercise, (2) reduction of systolic and diastolic blood pressure at rest and on exercise, (3) inhibition of isoproterenol-induced tachycardia, and (4) reduction of reflex orthostatic tachycardia. Nadolol has no intrinsic sympathomimetic activity and, unlike some other beta-adrenergic blocking agents, nadolol has little direct myocardial depressant activity and does not have an anesthetic-like membrane-stabilizing action. Like other beta-adrenergic antagonists, nadolol competes with adrenergic neurotransmitters such as catecholamines for binding at sympathetic receptor sites. Like propranolol and timolol, nadolol binds at beta(1)-adrenergic receptors in the heart and vascular smooth muscle, inhibiting the effects of the catecholamines epinephrine and norepinephrine and decreasing heart rate, cardiac output, and systolic and diastolic blood pressure. It also blocks beta-2 adrenergic receptors located in bronchiole smooth muscle, causing vasoconstriction. By binding beta-2 receptors in the juxtaglomerular apparatus, nadolol inhibits the production of renin, thereby inhibiting angiotensin II and aldosterone production. Nadolol therefore inhibits the vasoconstriction and water retention due to angiotensin II and aldosterone, respectively. Nadolol is used in cardiovascular disease to treat arrhythmias, angina pectoris, and hypertension.

Dobutamine is a sympathomimetic drug used in the treatment of heart failure and cardiogenic shock. Dobutamine hydrochloride is a direct-acting inotropic agent whose primary activity results from stimulation of the ß-receptors of the heart while producing comparatively mild chronotropic, hypertensive, arrhythmogenic, and vasodilative effects. It does not cause the release of endogenous norepinephrine, as does dopamine. Dobutamine directly stimulates beta-1 receptors of the heart to increase myocardial contractility and stroke volume, resulting in increased cardiac output. Dobutamine Injection, USP is indicated when parenteral therapy is necessary for inotropic support in the short-term treatment of adults with cardiac decompensation due to depressed contractility resulting either from organic heart disease or from cardiac surgical procedures.

Timolol is the non-selective Beta antagonist used as eye drops to treat increased pressure inside the eye such as in ocular hypertension and glaucoma. Timolol is also used for high blood pressure, chest pain due to insufficient blood flow to the heart, to prevent further complications after a heart attack, and to prevent migraines. Timolol is a beta1 and beta2 (non-selective) adrenergic receptor antagonist that does not have significant intrinsic sympathomimetic, direct myocardial depressant, or local anesthetic (membrane-stabilizing) activity. Timolol, when applied topically on the eye, has the action of reducing elevated, as well as normal intraocular pressure, whether or not accompanied by glaucoma. Elevated intraocular pressure is a major risk factor in the pathogenesis of glaucomatous visual field loss and optic nerve damage. The precise mechanism of the ocular hypotensive action of Timolol is not clearly established at this time. Tonography and fluorophotometry studies of the timolol maleate ophthalmic solution in man suggest that its predominant action may be related to the reduced aqueous formation. However, in some studies, a slight increase in outflow facility was also observed. In a study of plasma drug concentration in six subjects, the systemic exposure to timolol was determined following once daily administration of Timolol Maleate Ophthalmic Gel Forming Solution 0.5% in the morning. The mean peak plasma concentration following this morning dose was 0.28 ng/mL. Side effects, when given in the eye, include burning sensation, eye redness, superficial punctate keratopathy, corneal numbness.

Terbutaline is a relatively selective beta2-adrenergic bronchodilator that has little or no effect on alpha-adrenergic receptors. The drug has exerts a preferential effect on beta2-adrenergic receptors but stimulates beta-adrenergic receptors less selectively than relatively selective beta2-agonists. Terbutaline appears to have a greater stimulating effect on beta-receptors of the bronchial, vascular, and uterine smooth muscles (beta2 receptors) than on the beta-receptors of the heart (beta1 receptors). This drug relaxes smooth muscle and inhibits uterine contractions, but may also cause some cardiostimulatory effects and CNS stimulation. The pharmacologic effects of terbutaline are at least in part attributable to stimulation through beta-adrenergic receptors of intracellular adenyl cyclase, the enzyme that catalyzes the conversion of adenosine triphosphate (ATP) to cyclic- 3',5'- adenosine monophosphate (c-AMP). Increased c-AMP levels are associated with relaxation of bronchial smooth muscle and inhibition of release of mediators of immediate hypersensitivity from cells, especially from mast cells. Terbutaline is used for the prevention and reversal of bronchospasm in patients 12 years of age and older with reversible, obstructive airway disease, as well as symptomatic management of reversible bronchospasm associated with bronchitis and emphysema. Also used acute IV and sub-Q therapy in selected women to inhibit uterine contractions in preterm labor (tocolysis) and prolong gestation when beneficial.

Metaproterenol, also known as Orciprenaline, is a brochodilator that is FDA approved for the treatment of bronchial asthma and for reversible bronchospasm which may occur in association with bronchitis and emphysema. Metaproterenol Sulfate is a potent beta-adrenergic stimulator with a rapid onset of action. It is postulated that beta-adrenergic stimulants produce many of their pharmacological effects by activation of adenyl cyclase, the enzyme which catalyzes the conversion of adrenosine triphosphate to cyclic adenosine monosphosphate. Metaproterenol is a moderately selective beta(2)-adrenergic agonist that stimulates receptors of the smooth muscle in the lungs, uterus, and vasculature supplying skeletal muscle, with minimal or no effect on alpha-adrenergic receptors.

Isoproterenol (trade names Medihaler-Iso and Isuprel) is a medication used for the treatment of bradycardia (slow heart rate), heart block, and rarely for asthma. Isoproterenol is a non-selective β adrenoreceptor agonist and TAAR1 agonist that is the isopropylaminomethyl analog of epinephrine. Isoprenaline's effects on the cardiovascular system (non-selective) relate to its actions on cardiac β1 receptors and β2 receptors on smooth muscle within the tunica media of arterioles. Isoprenaline has positive inotropic and chronotropic effects on the heart. β2 adrenoceptor stimulation in arteriolar smooth muscle induces vasodilation. Its inotropic and chronotropic effects elevate systolic blood pressure, while its vasodilatory effects tend to lower diastolic blood pressure. The overall effect is to decrease mean arterial pressure due to the β2 receptors' vasodilation. The adverse effects of isoprenaline are also related to the drug's cardiovascular effects. Isoprenaline can produce tachycardia (an elevated heart rate), which predisposes patients to cardiac arrhythmias.

Ephedrine (l-form) is an alkaloid, which was initially purified from Ephedra plant. The extract form Ephedra has been used in China for medicinal purposes for several thousand years. Ephedrine acts as an agonist at alpha- and beta-adrenergic receptors and indirectly causes the release of norepinephrine from sympathetic neurons. The drug crosses the blood brain barrier and stimulates the central nervous system. Ephedrine products are now banned in many countries, as they are a major source for the production of the addictive compound methamphetamine. FDA has approved ephedrine only for the treatment of clinically important hypotension occurring in the setting of anesthesia.

Meluadrine (Hoku 81) is a beta-adrenergic receptor agonist with tocolytic activity. Meluadrine binds to and activates beta-2 adrenergic receptors of myometrial smooth muscle in the uterus, thereby activates adenyl cyclase, an enzyme that catalyzes the conversion of adenosine triphosphate (ATP) to cyclic-3',5'-adenosine monophosphate (cAMP). Increased cAMP levels leads to a reduction in intracellular calcium concentration, thereby causes smooth muscle relaxation and decreases the intensity of uterine contractions. Meluadrine is a bronchodilator, and one of the metabolites of tulobuterol. Meluadrine was approximately 8 times more potent than tulobuterol, approximately twice as potent as salbutamol, and approximately as potent as isoprenaline in relaxing effect on the isolated tracheal smooth muscle preparation of guinea pigs.

Carmoterol is a long-acting β2-adrenoceptor agonist with a rapid onset of action and potent bronchodilating activity. Carmoterol has a similar onset of action compared to salbutamol and formoterol, and a faster onset of action compared to salmeterol. Furthermore, the duration of tracheal smooth muscle relaxation is longer for carmoterol compared to both formoterol and salmeterol. In asthmatic patients, the PK of carmoterol is proportional to the dose, and nonlinear accumulation of the drug after repeated dosing treatments is negligible. In patients with persistent asthma carmoterol 2 µg administered once daily is as effective as formoterol 12 µg twice daily. Safety and tolerability results are similar between carmoterol and formoterol. There were no significant changes in ECG results, blood pressure or serum potassium or glucose levels

ICI-118551 is a selective β2 adrenergic receptor antagonist, that was originally developed for the regulation of blood pressure. ICI-118551 crosses the blood-brain barrier and it was in phase I clinical trials for the treatment of chronic anxiety. Currently, ICI-118,551 has no known therapeutic use in humans although it has been used widely in research to understand the action of the β2 adrenergic receptor, as few other specific antagonists for this receptor are known.