Many Patients Take Drugs That Interfere With Antihypertensives

By Lisa Rapaport

(Reuters Health) - People who take pills to lower their blood pressure often take other drugs that reduce the pills' effectiveness, a recent study suggests.

Researchers studied data on 521,028 adults prescribed antihypertensives for the first time and 131,764 people taking at least four different medications for refractory hypertension.

Roughly 18% were also taking drugs that interfere with antihypertensives, the study found, including non-steroidal anti-inflammatory drugs (NSAIDs), acetaminophen, and hormones.

"In some cases, use of these blood pressure-interfering medications may be justified and the potential side effect of elevations in blood pressure may be acceptable to patients," said study leader Andrew Hwang of the High Point University Fred Wilson School of Pharmacy in North Carolina.

"But in other cases . . . there may be significant opportunities to switch to alternative treatments or reassess the need for continuing the interfering treatment," Hwang said by email. "If these drugs can be discontinued, it's possible we can reduce the prescribing cascade - that is, reduce the need for using additional medication to treat a side effect of another medication."

Patients may not realize the risks, the findings suggest.

Among people recently prescribed blood pressure medications for the first time, 58% later refilled prescriptions for drugs known to increase blood pressure, the study found.

Among people prescribed four or more blood pressure drugs, 65% refilled drugs known to increase blood pressure after stepping up their blood pressure treatment regimen.

If blood pressure drugs are not working, it's important to consider not just other drugs that might influence blood pressure but also herbal medications that often are considered harmless, said Dr. Gunnar Gislason, a professor of cardiology at Copenhagen University Hospital Herlev and Gentofte and director of research at the Danish Heart Foundation, who wasn't involved in the study.

The way different drugs can increase blood pressure varies, Hwang said.

"Some drugs, such as NSAIDs and hormones, elevate blood pressure mainly by causing the body to retain excess fluid," Hwang noted. "This effect counteracts the mechanism of some blood pressure medications like diuretics."

"Other drugs can cause blood pressure elevation by constricting the blood vessels, increasing heart rate, or by a combination of mechanisms," Hwang added. "There are also some drugs, such as acetaminophen, that we know increase blood pressure, but we don't know how."

The study was published online July 25 in the American Journal of Hypertension.

"Although this study cannot tell us the reasons why the prescription rate of blood pressure-interfering medication is so frequent, it may explain why in (the) U.S. population blood pressure control is still very poor," said Dr. Liffert Vogt of Amsterdam University Medical Center.

"Poorly controlled blood pressure (is) a major cause of heart disease and stroke," Vogt, who wasn't involved in the study, said by email. "For that reason, prescribing drugs that contribute to poor blood pressure control should be carefully considered."

SOURCE: https://bit.ly/2OLgv0v

Am J Hypertens 2018.

(c) Copyright Thomson Reuters 2018. Click For Restrictions - https://agency.reuters.com/en/copyright.html

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