Nebivolol

Nebivolol is a β₁ receptor blocker with nitric oxide-potentiating vasodilatory effect used in treatment of hypertension and, in Europe, also for left ventricular failure. It is highly cardioselective under certain circumstances.

Pharmacology and biochemistry

β1 Selectivity

Beta blockers help patients with cardiovascular disease by blocking β receptors, while many of the side-effects of these medications are caused by their blockade of β2 receptors. For this reason, beta blockers that selectively block β1 adrenergic receptors (termed cardioselective or β1-selective beta blockers) produce fewer adverse effects (for instance, bronchoconstriction) than those drugs that non-selectively block both β1 and β2 receptors.

In a laboratory experiment conducted on biopsied heart tissue, nebivolol proved to be the most β1-selective of the β-blockers tested, being approximately 3.5 times more β1-selective than bisoprolol. However, the drug's receptor selectivity in humans is more complex and depends on the drug dose and the genetic profile of the patient taking the medication. The drug is highly cardioselective at 5 mg. In addition, at doses above 10 mg, nebivolol loses its cardioselectivity and blocks both β1 and β2 receptors. (While the recommended starting dose of nebivolol is 5 mg, sufficient control of blood pressure may require doses up to 40 mg). Furthermore, nebivolol is also not cardioselective when taken by patients with a genetic makeup that makes them "poor metabolizers" of nebivolol (and other drugs) or with CYP2D6 inhibitors. As many as 1 in 10 whites and even more blacks are poor CYP2D6 metabolizers and therefore might benefit less from nebivolol's cardioselectivity although currently there are no directly comparable studies.