People who take pills to lower their blood pressure often take other drugs that reduce the pills’ effectiveness, a large study suggests. Reuters Health reports that researchers studied data on 521,028 adults prescribed blood pressure pills for the first time and 131,764 people taking at least four different pills to lower their blood pressure.
Roughly 18% were also taking drugs that make blood pressure pills less effective, the study found. These include medicines like non-steroidal anti-inflammatory drugs (NSAIDs), acetaminophen, or 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. “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 realise the risks, the report says 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.
Patients who need blood pressure medicine should ask their doctor if any of the other medications they’re taking might interfere, said Dr Gunnar Gislason, a professor of cardiology at Copenhagen University Hospital Herlev and Gentofte and director of research at the Danish Heart Foundation.
And 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, Gislason, who wasn’t involved in the study, said.
The way different drugs can increase blood pressure varies, Hwang is quoted in the report as saying. “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 (water pills), which cause the body to get rid of fluid.”
“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 report says the study wasn’t designed to prove whether or how certain prescription drugs might interfere with the effectiveness of blood pressure medicines or increase blood pressure.
Another limitation is that it focused only on patients who were taking prescribed medicines that can interfere with blood pressure drugs, and many painkillers like acetaminophen and naproxen are available over the counter without a prescription in the US, the study authors note.
“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) US population blood pressure control is still very poor,” said Dr Liffert Vogt of Amsterdam University Medical Centre. “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.”
Background: Withdrawing medications that interfere with blood pressure (BP) is recommended in patients with uncontrolled BP, yet real-world use of such agents is not well characterized among individuals with hypertension. We aimed to evaluate the use of BP-interfering prescription medications among US patients with hypertension.
Methods: This retrospective drug utilization study used medical and prescription claims (January 2008 to December 2014) in the MarketScan commercial claims database. We included adults, aged 18–65 years, with a hypertension diagnosis (International Classification of Diseases, Ninth Revision, code 401) and ≥1 antihypertensive medication fill. Two hypertension cohorts were examined—new antihypertensive drug users (incident hypertension) and patients requiring titration to a fourth antihypertensive (incident treatment-resistant hypertension [TRH]). Patient-level exposure to BP-interfering medications was assessed 6 months before and after the index date, defined as the first prescription fill of an antihypertensive drug or the first occurrence of overlapping use of ≥4 antihypertensive drugs.
Results: We identified 521,028 patients with incident hypertension and 131,764 patients with incident TRH. The most prevalent BP-interfering prescription medications were nonsteroidal anti-inflammatory drugs (NSAIDs), acetaminophens, and hormones. Overall, 18.3% of the incident hypertension cohort and 17.6% of the incident TRH cohort initiated a BP-interfering medication following antihypertensive titration. Among patients previously taking a BP-interfering medication, 57.6% with incident hypertension and 64.9% with incident TRH refilled that medication after antihypertensive intensification.
Conclusions: The use of prescription BP-interfering medications, especially NSAIDs, is prevalent among patients requiring intensification of their antihypertensive regimen. Greater efforts to limit the use of these medications, where feasible, may be required among patients with uncontrolled hypertension.
Andrew Y Hwang Chintan V Dave Steven M Smith