Are gut microbes making a meal of our medication?

Ever wondered why some people respond well to a course of medication, while others hardly respond at all? It may have to do with the different levels of medication-munching microbes lurking in our guts, according to a new body of research.

Scientists from Harvard University and University of California San Francisco have just released results from an investigation into how gut microbiome interact with the medications we swallow. And the results suggest significant interference.

The research looked specifically at a drug used commonly in the treatment of Parkinsons disease, L-dopa. The drug is designed to deliver dopamine to the brain to relieve symptoms associated with Parkinsons, however it’s known that only 1- 5 per cent of the active ingredient actually reaches its intended target organ. Where does the remaining 95-99 per cent go?

It’s chewed up by gut bacteria, according to the new study, or more accurately, the medication is degraded by the actions of the bacteria. In the case of L-dopa, the chief antagonist was found to be a bacteria called Enterococcus faecalis and the bacteria’s enzyme, PLP-dependent tyrosine decarboxylase or TyrDC. Prevalence of this bacteria was found to be responsible for corrupting L-dopa significantly on its journey to the brain.

While this study looked specifically at a drug used to treat Parkinsons, it raises the very strong possibility that wide variations in people’s responses to many other drugs may be caused for the same reasons – specifically, differences in the make-up of our gut bacteria.

Vayu Maini Rekdal, first-author of the study, speculates that variations in the make-up of a person’s gut microbiome may also be the reason why some people experience severe side effects to a medication while others don’t.

“All of this suggests that gut microbes may contribute to the dramatic variability that is observed in side effects and efficacy between different patients taking L-dopa,” Maini Rekdul said.

The research paper concludes, “But this microbial interference may not be limited to L-dopa and Parkinson’s disease. (The) study could shepherd additional work to discover exactly who is in our gut, what they can do, and how they can impact our health, for better or worse.”

While the authors of the study suggest this research will pave the way to develop new drugs to inhibit the medicine-eating effect of Enterococcus faecalis, this only has implications for people taking L-dopa. Across the world, the number of drugs that might be adversely affected by different kinds of gut bacteria could number in the thousands. Developing a picture of which gut bacteria degrades what medications will be a prohibitively expensive exercise taking many years – but it’s a project worthy of doing if it means medications become more effective and side effects become less severe.

However while we’re waiting for the results of all this research to come in, there are ways to administer medicine that largely by-pass the digestive system – and gut microbiome – completely. These methods can be used in cases where it’s suspected, or known, that the medication is being degraded before it reaches its intended target:

The most obvious method is by an intravenous injection; delivering medication straight into the blood stream. However injections are invasive and not simple to administer in the home.

An easier at-home option is a troche placed under the tongue. With this method the medication is absorbed into the blood stream through the very thin lining of skin covering the numerous blood vessels that line the mouth.

Some medications can also be administered directly into the blood stream through topical creams applied to the arms, legs and torso, however this kind of administration is limited to the kinds of medications that can penetrate external skin, and these are not many.

Many commercial medications can be made up as a troche or cream by a fully licensed compounding pharmacy like National Custom Compounding. For more information call us on 1300 731 755 or drop a line to [email protected].

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