Scientists pinpoint what turns three common drugs into toxic weapons

8 Feb 2019

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The unintended side effects of medication can often come as a surprise to some, but new findings may have discovered the culprit.

Despite the best intentions of pharmaceutical companies in the production of some medication, there is a small minority of cases where the treatment that works for the many actually harms the few.

Now, after examining what is creating these toxic effects, researchers from Yale University and ETH Zurich believe they have found what is behind this, and admit it came as a surprise.

Publishing its findings in Science, the research team pointed the finger at our own vital, delicate gut microbiome and how bacteria found there can transform three particular drugs into harmful toxins.

The first drug used during testing was an antiviral drug that causes a severe toxic reaction in some, and the researchers watched to see how gut bacteria turned it into a harmful compound. Afterwards, the team administered the drug to mice carrying bacteria engineered to lack this drug-transforming ability, and measured the levels of toxic compound.

The data gathered from that experiment was then used to develop a mathematical model to successfully predict the role of gut bacteria in metabolising a second antiviral drug and clonazepam, an anti-seizure and anti-anxiety drug.

The results showed that the gut microbiomes were responsible for producing between 20pc and 80pc of the circulating toxic metabolites derived from the three drugs. With the new predictive model, researchers in the future will be able to potentially identify those most at risk of side effects from a range of different drugs.

“If we can understand the microbiome’s contributions to drug metabolism, we can decide which drugs to give to patients or even alter the microbiome so patients have a better response,” said the study’s co-lead author, Michael Zimmermann.

Much like the human mind, the gut microbiome often poses many more questions than answers, though another recent breakthrough did help identify 100 new gut bacteria living within us.

In creating the most comprehensive collection of human intestinal bacteria to date, the new resource will help researchers worldwide to investigate how our microbiome keeps us healthy, and its role in disease.

Colm Gorey was a senior journalist with Silicon Republic