"There has been a lot of concern about this," said Dr. Sheila Fallon Friedlander at the annual Hawaii Dermatology Seminar sponsored by Skin Disease Education Foundation, in comments published on 5/1/10 in Internal Medicine News. "You can't say anything with certainty in life, but at least thus far the data we have are very reassuring that there is no association."
A seven-country systematic data search led by gastroenterologists at the University of North Carolina at Chapel Hill found "no clear relationship" between the use of isotretinoin and IBD. An earlier retrospective, nested-case study by investigators at the University of Manitoba utilized the comprehensive provincial IBD database to demonstrate that patients with IBD were no more likely than matched controls to have used isotretinoin prior to diagnosis of IBD.
"Our data suggest that isotretinoin is not likely to cause chronic IBD," the study authors concluded.
Dr. J. Mark Jackson of the University of Louisville, Kentucky, a longtime prescriber of isotretinoin for severe acne cases, told Internal Medicine News that "we now have some very good data reviews showing that IBD is not overrepresented in patients who use isotretinoin. When this issue comes up [in prescribing], we need to make people aware that this rumor has not been validated."
Dr. Seth D. Crocket of the University of North Carolina, who works in gastroenterology and hepatoplogy at the campus, co-authored the American investigation. "Our study was a critical appraisal of the literature and an assessment of causality," he indicated in an interview. "Basically we found that the only published evidence is case reports, which generally is considered poor evidence to establish causality. The best evidence is from epidemiologic studies such as the University of Manitoba study.
"It's important to recognize that the absence of published evidence does not mean the absence of an association; it just means that there's insufficient evidence in the scientific literature thus far to support a causal connection between isotretinoin and IBD."
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Dr. Jackson of the University of Louisville characterized the Manitoba study as "a really well-done study coming at a critical time," conducted by physicians who deal with IBD and therefore have no stake in protecting a drug that could cause it.
It should be noted that Dr. Jackson disclosed that he has received support from Roche Pharmaceuticals, the manufacturer or Accutane, according to disclosures cited in the Internal Medicine News article. Dr. Friedlander is also identified as a longtime prescriber of isotretinoin for severe acne.
While both studies suggested that isotretinoin was not likely to cause IBD, "there may be anecdotes of isotretinoin causing acute colitis," Dr. Friedlander said.