Interactions of Gut Bacteria and Oral Drugs Might Have Clinical Implications

Among people who have the same disease, a particular drug can vary greatly in its effectiveness and adverse effects. Although some of this variability is due to each patient's unique genetics, a new study adds to the evidence that some of the variability also might be due to patients' gut flora.

Investigators studied the effects of 15 drugs on 25 strains of human gut bacteria and found a remarkable variety of drug–bacteria interactions. For a given agent, some bacteria store the drug without chemically modifying it, whereas other bacteria chemically modify it to make it more or less bioactive. Either way, the gut bacteria can affect the amount of a drug (or an active drug metabolite) that is available to the body. The converse also can happe…