PSYLLIUM STUDIES OF LONG-TERM EFFECTS ON CHOLESTEROL ARE NEEDED FOR OTC CHOLESTEROL-LOWERING USE, FDA TELLS P&G (METAMUCIL) AND RYDELL (FIBERALL)
Psyllium's long-term effects on cholesterol must be established before the ingredient can be marketed OTC with either professional or consumer label claims for cholesterol reduction, FDA OTC Drug Evaluation Division Director William Gilbertson, PharmD, told Procter & Gamble and Rydelle Labs in July 29 letters. "It is imperative to establish that psyllium results in sustainable clinically significant reductions in total and LDL cholesterol," Gilbertson said. "The Division of OTC Drug Evaluation is therefore proposing that serum cholesterol lowering claims for psyllium hydrophilic mucilloid not be included in either professional or consumer labeling at this time." Gilbertson also noted that FDA has some concerns regarding the safety of long-term use of psyllium. "From a safety point of view," he said, "the effects of long-term treatment with psyllium hydrophilic mucilloid on intestinal absorption and/or metabolism minerals (e.g., iron, calcium, zinc) and fat-soluble vitamins (e.g., A, D, and K) have not been clearly determined." Gilbertson's letter responds to September 1987 petitions from both companies to allow a cholesterol reduction claim for the ingredient in the laxative final monograph. Psyllium, which was classified as a Category I laxative ingredient in the Laxative Tentative Final Monograph, is the active ingredient in both Procter & Gamble's Metamucil and Rydelle Lab's Fiberall powder and wafers. Rydelle, however, has just signed an agreement to sell the product to Ciba-Geigy's consumer product group (see next story). Based on a review of 37 studies referenced by Rydelle and 29 studies referenced by Procter & Gamble to support the hypercholesterolemia indication, Gilbertson said that a Metamucil study conducted by Anderson, et al., and five other psyllium studies "provide some evidence for the efficacy of the drug." However, he concluded that "substantial evidence from adequate and well-controlled studies is lacking." The division director outlined a number of issues that should be resolved in future studies to support the indication. "The product's effects on HDL-cholesterol (or lack of effect) need to be determined in both sexes and in a much larger study than that reported by Anderson," Gilbertson said. The Anderson study, which compared Metamucil to placebo in 28 males for 10 weeks, found that total and low-density lipoprotein (LDL) cholesterol were lowered "by 11.7% and 18% over the 3.6% and 2.6% reductions seen in the placebo group, respectively," FDA noted. However, Gilbertson said, it is "unknown whether a larger study might show an effect on HDL cholesterol, as was the case for cholestyramine." Discussing additional areas for study, Gilbertson said "it is important to establish a dose-responsive curve for psyllium, [and]. . . mechanism of action studies must be pursued much more intensively." Also, he continued, "it may be necessary to establish that formulations of psyllium hydrophilic mucilloid other than those previously studied are bioequivalent in lipid-altering efficacy, i.e., do excipients, particularly polymeric ones, have a modulating effects on psyllium's action on lipids." The division director added that "at some point, evaluation of the adjunctive use of psyllium on cardiovascular morbidity and mortality may be appropriate." The extensive list of data that FDA is requesting may make the OTC claim more attractive for an NDA submission than a monograph submission. Neither P&G nor Ciba Consumer would speculate on whether or not the NDA route might be used in an attempt to get exclusivity. P&G, However, said that it plans to pursue additional studies using the guidance in FDA's letter.
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