Laxative Poses Cancer Risk, Says FDA Panel

The US Food and Drug Administration's Carcinogenicity AssessmentCommittee has voted that phenolphthalein, the active ingredient in many laxative products, may pose a carcinogenic risk to humans. The vote was based on the results of studies which showed that it is carcinogenic in rats. The FDA is reviewing the recommendations made by the CAC and is expected to make a decision on the products following the close of a public comment period on June 13.

The controversy goes back to December 1995, when the National Toxicology Program in the USA released data from a study looking at the effects of chronic administration of high doses of phenolphthalein over the lifespan of rats, and uncovered a risk of cancer. In 1996, the CAC suggested that this was not relevant to human use, and the FDA called for new studies to be performed in rats and mice. The CAC reviewed data from these new studies at its last meeting.

Notable products which may be affected by the action include the Ex-Lax range from Novartis Consumer Health. Other manufacturers, including Schering-Plough which markets bisacodyl-based products, have been quick to take advantage of the vote and issue statements pointing out that their products do not contain phenolphthalein, and that their safety is not in question.