Consistent with the side effect information listed in the Physician's Desk Reference, use of isotretinoin appears to increase the risk of inflammatory bowel disease (IBD), US researchers report in the American Journal of Gastroenterology for July. NEW YORK (Reuters Health) - Consistent with the side effect information listed in the Physician's Desk Reference, use of isotretinoin appears to increase the risk of inflammatory bowel disease (IBD), US researchers report in the American Journal of Gastroenterology for July.

Isotretinoin was first approved for acne in the US in 1982, and numerous case reports have surfaced linking the drug to IBD. Until now, a systematic review of the association had not been conducted.

Dr. Corey A. Siegel, from Dartmouth-Hitchcock Medical Center in Lebanon, New Hampshire, and colleagues reviewed all reports of isotretinoin-associated IBD that were filed with the US Food and Drug Administration via the MedWatch system, which began in 1996.

The authors used a standard measure called the Naranjo adverse drug reaction probability scale to grade the likelihood that a particular IBD case was, in fact, caused by isotretinoin use.

Between 1997 and 2002, a total of 85 isotretinoin-related cases of IBD were reported. In 4 cases, isotretinoin was graded as a "highly probable" cause of the IBD, in 58 as a "probable" cause, and in 23 as a "possible" cause. The causative link between isotretinoin use and IBD was never graded as "doubtful".

"Physicians and patients should be made aware of this possible association and it should be included in the already extensive consent process required before isotretinoin is prescribed," the authors conclude.

"We do not think that this should prohibit the use of isotretinoin," they advise, "but careful consideration should be made in those patients at higher risk for inflammatory bowel disease (prior personal history, family history) or with symptoms suggestive of inflammatory bowel disease."

Am J Gastroenterol 2006;101:1569-1573.