A new study published this month in the journal Hypertension has shown gut bacteria can reduce the effectiveness of certain antihypertensive drugs. The research provides the first clues into why some people not respond well to medication.
Among those with hypertension, an estimated 20% have resistant hypertension, where their blood pressure remains high despite aggressive treatment.
“The only thing doctors can really do in these patients is adding or switching medications and increasing the dose with the hope they can find something that works,” said Dr Tao Yang, an assistant professor at University of Toledo and the study’s first and lead author. “Until now, we haven’t had any clear indication what the mechanism is for resistant hypertension. Our research could provide a first step toward identifying new ways to effectively overcome treatment-resistant hypertension.”
Recent research has focused on the link between blood pressure and the gut microbiome. That work has helped to unravel potential causes of hypertension beyond diet and exercise. However, Dr Yang’s research is the first to examine the impact of gut bacteria on blood pressure medication itself.
In the study, UToledo scientists compared the effectiveness of the antihypertensive drug quinapril in rats with normal gut bacteria against those with gut microbiota depleted by high doses of antibiotics.
Researchers found a clear difference between the two, with animals that were given antibiotics first responding much better to quinapril.
Analysis of the gut bacteria composition in the animals identified the bacteria Coprococcus as the culprit. Laboratory experiments proved that Coprococcus comes, a dominant bacteria species in this genus, can break down quinapril and ramipril, resulting in the compromised blood pressure-lowering effects.
While the study was confined to animal models and lab experiments, researchers did find at least one intriguing case study that seems to support the notion that this could be applicable to humans.
That 2015 report, published in the International Journal of Cardiology, described a woman with a long history of treatment-resistant hypertension whose blood pressure was controlled without any antihypertensive medication for the two weeks she was taking antibiotics for a post-surgical infection. Her blood pressure was able to be controlled with only one medication for six months after stopping antibiotics, before again becoming treatment-resistant.
“This is just one report and more research is needed. However, this suggests that gut bacteria can play a very real and very important role in regulating the efficacy of blood pressure medication,” Dr Yang said.
The research group intends to further explore the interaction between additional blood pressure medications and other common types of gut bacteria.
Though long-term use of antibiotics isn’t a realistic strategy for addressing treatment-resistant hypertension, Dr Yang said it should be possible for someone to alter their microbiota through probiotics, prebiotics and changes in diet.
“The ultimate goal of my research is to identify ways we can specifically target the bacteria in an individual’s gut to improve drug efficacy,” he said. “This has the potential to benefit a lot of people.”
Source: University of Toledo
