The ingredient combination of zinc chloride, sodium citrate, hydrogen peroxide and sodium lauryl sulfate is Category I for safety, but efficacy data for the dental rinse combo are insufficient to determine its effectiveness for antiplaque/antigingivitis claims, FDA's Dental Plaque Subcommittee recommended unanimously at the group's final meeting in Rockville, Md. Dec. 2-3.

The combo is used in Prevention Labs' Prevention Mouthrinse, which the subcommittee reviewed at its May 27-29 meeting. At the time, the subcommittee decided to re-review the safety of the Prevention product after suggesting the need for a six-month clinical trial ("The Rose Sheet" June 8, p. 9).

Subcommittee member Max Listgarten, DDS, University of Pennsylvania, presented the summary review of studies of the product in comparison to Warner-Lambert's Listerine in hamsters and a double-blind clinical trial of the various active ingredients in Prevention.

Listgarten said the test results show "the available data indicate the product is safe for the use as a mouthrinse and therefore, it will be a Category I for safety."

However, "the animal and clinical data fail to support the claims made by this product...and specifically indications for the use of this rinse or statements that exclude gingival hemorrhage and...gingivitis as a treatment two weeks prior to periodontal treatment."

"I don't think these indications are supported by clinical data," Listgarten concluded. "Therefore, while the product may be considered safe, it is not considered effective for those indications listed. As for those periodontal indications, the product will have to be categorized as Category III."

A 30-day Prevention study involved topical applications of the mouthrinse to the abraded and non-abraded cheek pouches of hamsters in solutions of .12% chlorhexidine digluconate, 1%, 2% and 3% hydrogen peroxide and 5% sodium lauryl sulfate. A control group received topical applications of water.

Those animals receiving applications of Prevention "gained weight normally and did not demonstrate any evidence of mucosal irritation in the form of inflammation, hyperplasia, atrophy and hyperkeratosis versus the water control subjects." The mouthrinse also did not interfere with healing of abraded hamster cheek pouches.

Prevention Mouthrinse was tested in a 30-day study involving 76 hamsters divided into three groups with equal numbers of male and female animals.

For comparison, one group of animals received topical applications of 5% SLS on their cheek pouches, another group received topical applications of Listerine, and a group of 10 animals received topical applications of Listerine and water.

Test results showed no evidence of mucosal irritation in the form of epithelial damage, inflammation, atrophy and hyperkeratosis, Listgarten said.

In a double-blind study conducted on 119 human adults, subjects were fitted with tooth shields that covered a specific quadrant to enable plaque to accumulate on a controlled area of teeth.

The subjects were assigned to one of three experimental groups that, in addition to brushing their teeth, rinsed with varying formulations of mouthrinse.

The test results showed "no statistically significant differences in gingival or index scores or bleeding sites...either on the shielded or non-shielded teeth," Listgarten said.

While plaque scores increased for those subjects with shielded teeth, Listgarten noted the results were "not clinically significant....None of the tested rinses had any effect on the prevention of gingivitis," he said.

The subcommittee had planned to review the ingredients triclosan and the combination of triclosan and zinc citrate; however, FDA Center for Drug Evaluation & Research Liaison Robert Sherman, announced the ingredients would not be reviewed and will be completed separately.

The subcommittee's final report on ingredients to be included in the final monograph for antiplaque/antigingivitis claims is expected out in two to three months, the group said.

Zinc Chloride, SLS Dental Rinse Combo Needs More Efficacy Data

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