‘Inactive’ drug ingredients aren’t always inactive, study finds

Common pills including ibuprofen and antacids often have inactive ingredients that add color or act as preservatives, but a new study finds that these ingredients may not always be lacking activity. Some of these components could interact with a drug's molecular target and potentially cause side effects, researchers concluded, after analyzing 600 common inactive ingredients — called excipients — against 3,000 molecular targets. Thirty-eight excipients were found to have more than 130 previously unknown activities against biological targets, and five excipients had activity that could have caused toxicity to tissues. Although the study didn't establish whether any of these inactive ingredients actually caused side effects, the FDA ought to more regularly look at how excipients interact with specific targets as part of drug evaluations, the authors say.