What is a beta blocker? Why they are vital to those with various heart diseases

One way or another, beta blockers are always in the news. Take, for instance, Los Angeles Chargers Head Coach Jim Harbaugh, who revealed in October that he's part of a growing group of Americans who suffer from heart disease.

Nearly 127.9 million Americans aged 20 and older battle with cardiovascular diseases, according to the American Heart Association and National Institutes of Health joint annual study. Harbaugh's fight is with atrial flutter, a condition where the heart's upper chambers beat faster than the lower chambers, something he has in common with millions of Americans. The disorder is one of many other heart-related problems that can be maintained through beta blockers, a classification of drugs, according to the AHA.

"They have an impact in terms of blood pressure control and with that, can have significant beneficial impact on the cardiovascular system," AHA Volunteer President Dr. Keith Churchwell, who specializes in cardiovascular medicine.

What is a beta blocker?

Churchwell said the drug class slows the heart by inhibiting and binding to beta one and beta two receptors on the heart. They limit the production of epinephrine, norepinephrine, adrenaline and noradrenaline, which helps lower a person's blood pressure.

They're prescribed to people with some irregular heart rhythms, heat attacks, heart failure, chest pain and other cardiovascular problems. Churchwell added beta blockers are one of the most prescribed drugs to treat the heart. He said some doctors will use it to treat anxiety disorders and migraines.

"They have quite a bit of extensive utilization because of their ability to treat a number of disorders," Churchwell said.

Sir James Black discovered the class of drugs in 1964, according to the National Institutes of Health. He showed other scientists that the medicine could be developed by "applying basic knowledge of receptor-driven cell-signalling systems to clinical problems."

According to healthcare company GoodRx, the eight most common generic beta blocker drugs are metoprolol, carvedilol, atenolol, propranolol, labetalol, bisoprolol, timolol and nadolol. Anyone prescribed the medication is typically required to take them for the rest of their lives or long-term, Churchwell said.

"Patients may need, over time, to have their doses reduced, given their increase in overall sensitivity," he said. "Patients may actually develop an adverse response to beta blockade."

Types of beta blockers

The Cleveland Clinic classified beta blockers into two categories, cardioselective and nonselective, according to its website. The latter is for medicines that block the B1 receptors found in the heart, which when activated, focus on elevated heart rate, increasing pumping force and releasing a kidney enzyme called renin.

Cardioselective beta blockers acebutolol, atenolol, betaxolol, bisoprolol, esmolol, metoprolol and nebivolol. Nonselective ones are carvedilol, labetalol, nadolol, penbutolol, pindolol, propanolol, sotalol and timolol. Some of the medications, the clinic said, can lower both heart rate and blood pressure, are only available in intravenous forms and can expand blood vessels.

How many people take beta blockers?

About 30 million people take beta blockers in the United States, according to the Cleveland Clinic, a medical research and treatment facility headquartered in Ohio.

The White House said in an April statement that particular Medicare recipients can get generic versions of the drugs for $2. The news came during his pitch on how the federal government will expand access to health care and increase the affordability of medications.

What are the side effects of beta blockers?

Like any drug, taking beta blockers comes with side effects. Churchwell said they can cause bronchial constriction, which can be a problem for people with chronic lung disease, asthma and diabetes. He added the drugs can mask symptoms of hypoglycemia as the blockers limit the effects of adrenaline.

"We have to be thoughtful about patients who are diabetic in terms of taking beta blockers," he said. "They do slow the heart rate, which is good, but also can lead to fatigue."

According to the Mayo Clinic, the other side effects of taking beta blockers are:

• Cold hands or feet

• Extreme tiredness

• Weight gain

• Dizziness or lightheadedness

• Shortness of breath

• Trouble sleeping

Who shouldn't take beta blockers?

Not everyone's medical condition is suited for beta blockers. Churchwell said that people with asthma and chronic obstructive pulmonary disease are on a specific form of a beta blocker to avoid worsening lung functions.

He added people who've had allergic or otherwise adverse reactions to beta blockers shouldn't take the medication. But if they are necessary, he said doctors will typically prescribe smaller doses and monitor how a person's body reacts to the medicine.

According to the Cleveland Clinic, people with certain types of heart arrhythmias shouldn't take the drugs as they can aggravate some heartbeats.

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This article originally appeared on USA TODAY: What is a beta blocker? Why they're vital to those with heart diseases