Gut bacteria shown to affect statin efficacy in some people

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Researchers have found why statins or cholesterol lowering drugs work in some but not others. Gut bacteria may be the reason.

The team led by a Duke University scientist has identified three bile acids produced by gut bacteria that were evident in people who responded well to a common cholesterol-lowering drug called simvastatin. The finding, published Oct. 13, 2011, in PLoS One, demonstrates how gut bacteria can cause inherent differences in the way people digest, metabolize and benefit from substances such as drugs.

This study belongs to a new branch of science of drug action – metabolomics, which examines the thousands of biochemical components involved in cellular metabolism and how they affect health.

Lead author Rima Kaddurah-Daouk, associate professor in Duke's Department of Psychiatry and leader of the Pharmacometabolomics Network said, “This is personalized medicine – the effects of drugs and how we respond… We found that the benefit of statins could be partly related to the type of bacteria that lives in our guts. The reason we respond differently is not only our genetic makeup, but also our gut microbiome.”

For the study the team gathered data from a subset of participants enrolled in a large, national project called the Cholesterol and Pharmacogenetics (CAP) study, which was led by co-author Ronald M. Krauss, of Children's Hospital Oakland Research Institute. In the small trial Kaddurah-Daouk, Krauss and colleagues identified 100 people from the CAP study whose LDL cholesterol fell dramatically as a result of taking simvastatin; 24 who had a fairly good response on the drug; and 24 who showed little benefit.

Thereafter they analyzed the blood from the participants before any had taken the drug, searching for known bile acids and fat-like substances called sterols that are involved in the body's break-down and use of cholesterol.

Results showed that among the group who a strong response to the drug three bile acids had appeared to play a role. The bile acids are produced by certain gut bacteria. Among the people who responded poorly to the statin, five different bile acids were commonly evident.

The researchers hypothesize that because bile acids and statins share transporter routes to the liver and intestines producing more or less of certain bile acids could improve or diminish the drug's effects.

A blood test that screens for these specific bile acids could provide a way for doctors to determine who would respond to simvastatin and who would not. Additionally, new strategies could be developed to manipulate the gut microbiome using probiotics to spur different gut bacteria, which could then give the drugs a boost.

“We really need to partner with diagnostic and pharmaceutical companies to target drugs for subpopulations,” Kaddurah-Daouk said. “It's no doubt that metabolites from bacteria are playing an important role in regulating our systems. We're at a very early stage of understating this relationship, but eventually we could take a quick chemical assay and get a read on where we are metabolically.”

Dr. Ananya Mandal

Written by

Dr. Ananya Mandal

Dr. Ananya Mandal is a doctor by profession, lecturer by vocation and a medical writer by passion. She specialized in Clinical Pharmacology after her bachelor's (MBBS). For her, health communication is not just writing complicated reviews for professionals but making medical knowledge understandable and available to the general public as well.


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