Roughly one-third of the drugs reviewed as part of an iniative to monitor pediatric meds resulted in changes to labeling and production of Medication Guides. And several more required continued monitoring for side effects, according to a study in Pediatrics.

You may recall the FDA Modernization Act provides an additional six months of marketing exclusivity to companies that perform pediatric trials, but because some safety concerns aren’t detected until after marketing, the FDA is required to report to advere events its pediatric advisory committee occurring during the first year after exclusivity is granted.

And so a group of FDA employees and Duke University researchers reviewed the committee’s recommendations over four years on 67 drugs that were granted exclusivity. The upshot: safety monitoring during the early postmarketing period is crucial to detect rare, serious, or pediatric-specific adverse events.

Why? Several side effects revealed during the advisory reviews “were rare and life-threatening,” according to the study. Monitoring helped identify red lights that weren’t previously noticed.

For instance, after the committee’s recommendations, Roche’s Tamiflu labeling was changed to include psychiatric risks, Johnson & Johnson’s Duragesic carried new warnings about inappropriate use and J&J’s Ditropan labeling carried a caution about hallucinations in children, according to the study.

The research didn’t examine how often the agency took the actions recommended by the advisers, and the FDA couldn’t immediately say in how many cases it followed the advice, an FDA spokeswoman tells Bloomberg News.

Of 67 drugs reviewed by the committee between June 2003 and April 2007, 44 or 66 percent, were returned to routine monitoring for adverse. The committee recommended label changes for 12, or 18 percent, continued monitoring for 10, or 15 percent, MedGuides for nine, or 14 percent, and an update on label changes resulting from discussions with the sponsor for one drug.

“Fortunately, the majority of drugs given exclusivity had no adverse events of a frequency or severity that prevented a return to routine adverse event monitoring,” the authors concluded.