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The development of newer antihypertensive drug classes—ACE inhibitors and angiotensin receptor blockers (ARBs), in particular—has made ß-blockers a less attractive option for managing high blood pressure than they were initially. This is largely because ACE inhibitors and ARBs are associated with fewer side effects and are better tolerated. However, the value of ß-blockers is undisputed in patients with coronary artery disease (CAD) and heart failure. Much evidence has demonstrated that hypertensive patients with previous myocardial infarction (MI) or who possess other clear evidence for CAD and/or heart failure have better mortality outcomes when treated with ß-blockers. The agents also prevent further major cardiac events in this patient group.

New ß-Blockers Developed

The use of ß-blockers for hypertension had started to diminish in recent years (except for patients with CAD and heart failure), but the emergence of vasodilator ß-blockers has rekindled interest to use these drugs in select patients. Currently, two agents qualify as vasodilator ß-blockers: carvedilol and nebivolol. The mechanisms of action for these drugs are different from previous ß-blockers. In the case of carvedilol, beyond functioning as a non-selective ß-blocker, it has ß-blocking properties. This can improve tolerability and help patients avoid the unwanted metabolic effects commonly seen with traditional ß-blockers.

Nebivolol is the newest vasodilator ß-blocker to be approved by the FDA. With regard to hemodynamic and metabolic properties, nebivolol is similar to carvedilol, but these agents work differently. Carvedilol is a non-cardioselective ß-1, ß-2, and ß-receptor blocker. Nebivolol, on the other hand, is more cardioselective than any other available agent because it primarily blocks ß-1 receptors. It also produces vasodilation and reduces total peripheral resistance, brought about by enhancing vascular nitric-oxide release. This improves endothelial function, thereby potentially leading to additional benefits above and beyond ß-blockade or blood-pressure lowering alone. Although nebivolol has shown some benefits in treating heart failure in elderly populations, it’s not yet approved for this indication.

Choosing Between Vasodilator ß-Blockers

Currently, the majority of the available evidence demonstrates that carvedilol benefits patients with heart failure or MI, but many hypertensive patients may benefit with nebivolol. The agent appears to work equally well across various patient subgroups, including older and younger individuals as well as African Americans and Caucasians. As with all ß-blockers, nebivolol should not be used in patients with asthma or airway disease, or in those with peripheral arterial disease. Physicians should understand that complaints of respiratory difficulty may rarely occur with nebivolol, but should immediately recognize that this problem could be the result of ß-blocker use. In general, the drug has antihypertensive efficacy similar to that of other approved ß-blockers.

While nebivolol should prove useful in treating hypertensive patients because of its wide-ranging efficacy and its favorable side-effect profile, it’s important to note that its actions may not necessarily improve cardiovascular outcomes beyond those expected from effective blood pressure reduction. However, when compared with traditional ß-blockers, the drug is patient-friendly because it lowers vascular resistance and systemic blood flow, and has few, if any, metabolic adverse effects. Complaints such as fatigue, decreased exercise tolerance, or reduced sexual function are less likely than with traditional ß-blockers. Such features are likely to make nebivolol an attractive treatment option for physicians and patients alike.

Michael A. Weber, MD, has indicated to Physician’s Weekly that he is a member of the speakers’ bureau for Boehringer-Ingelheim, Bristol Myers Squibb, Daiichi Sankyo, Forest Pharmaceuticals, Glaxo Smith Kline, Merck, Novartis, Pfizer, and Sanofi-Aventis. He also serves as a consultant for Boehringer-Ingelheim, Bristol Myers Squibb, Daiichi Sankyo, Forest Pharmaceuticals, Gilead, Merck, Novartis, and Takeda Pharmaceuticals.