What was known before
Scientists have already demonstrated that bacteria that live in the gut can influence the effectiveness of drugs that people take. A previous study looked at the effects of gut enzymes on 271 drugs. It was negative for 176 drugs. In 2020, scientists described how a waste product of certain bacteria (imdazole propionate) could inhibit the activity of metformin, a common drug used to treat type 2 diabetes.
It is also known that the gut microbiome can affect how some cancer drugs work. Certain bacteria can increase the toxicity of chemotherapy.
What turned out
In a new study, scientists from the University of Cambridge and the European Laboratory of Molecular Biology focused on how 25 strains of common gut bacteria affect 15 commonly used drugs taken by mouth.
Scientists report that their findings came as a surprise to them. Most of the interactions between bacteria and drugs have been due to the microbes being able to absorb and store drugs. Previously, this mechanism was not considered as an important factor: it was believed that the main role in interactions belongs to the biotransformation of drugs.
In total, in a laboratory study, the authors found 70 different interactions between bacteria and drugs, 29 of which were not previously described. 17 newly discovered effects were associated with the accumulation of drugs by bacteria. These drugs include roflumilast (used for chronic obstructive pulmonary disease), montelukast (for bronchial asthma), rosiglitazone (for diabetes mellitus).
Using the antidepressant duloxetine as an example, scientists investigated the molecular mechanisms of drug accumulation in intestinal bacteria. It turned out that the medicine is not only “stored” in the microbe, but also affects what substances it secretes. Other gut bacteria were affected by this change, and their population changed.
In an experiment on roundworms, the researchers found that bacteria are able to absorb enough medicine to affect their effectiveness. The effect of the drug on the behavior of the worms varied depending on which bacteria colonized their intestines.
Scientists point out that the study of the interaction of gut bacteria with drugs is only in its early stages. It will be difficult to answer the question of how these interactions affect the clinical efficacy of drugs. The composition of the gut microbiota is unique to each person, so interactions with drugs will differ from person to person.
Next, scientists plan to study how the human gut microbiome is related to how it responds to taking antidepressants.