FDA may consider a standardized sunscreen testing method for higher-SPF products if sufficient additional information is provided and found acceptable, the agency said at a working group meeting with industry in Rockville, Md. Oct. 26.

The agency told the Cosmetic, Toiletry & Fragrance Association that the trade group's proposed SPF 15 preparation standards may serve as an alternative to the current method used to determine SPF level accuracy in the sunscreen final monograph. The reg was published in the May 21 Federal Register (¹ Also see ""SPF 30 Plus" Term Required For High-Protection Sunscreens - FDA Final Reg" - Pink Sheet, 24 May, 1999.).

The agency believes the data submitted could support the CTFA methodology as an appropriate SPF 15 standard if additional information demonstrates that multiple laboratories can successfully use the standard, FDA Division of Dermatology & Dental Drug Products Reviewer Paul Brown, PhD, stated.

The standard used to measure SPF values up to 30 "represents at this time a straightforward, well-understood and sound method," the sunscreen monograph states. However, recognizing that "testing methods in this arena are evolving," the agency leaves open the possibility for amendments if accurate methods for testing high SPF values are confirmed.

The SPF measurement method outlined in the reg is a standard sunscreen preparation with an SPF level of 4.47. "The use of this low SPF standard may not accurately estimate errors in SPF determinations at higher SPF values," Brown acknowledged.

A standard SPF determination, the FDAer said, can "serve as an interval indicator of experimental error. If the standard is not accurately measured, then the study is not considered valid." Necessary properties of a suitable method standard include a low level of variation across labs, sensitivity to experimental error and ease of preparation with a certain degree of accuracy, he continued.

FDA initially told CTFA in a Sept. 2 letter one of the two SPF standards submitted by the trade group could be used as an appropriate standard. The association had tested the preparations on 153 subjects in a round-robin study involving seven labs.

While the CTFA standard was found to have a low variability between labs, "the study did not specifically address whether the standards were sensitive to experimental errors," Brown noted. He did point to one lab where "erroneous SPF values were measured with an improper sunscreen application technique. The data from this lab suggest that the standard sunscreens were able to detect this particular type of error."

Two additional studies received by the agency from Schering-Plough and Hawaiian Tropic indicate assays can differentiate between products with SPF values of 15 and higher with low variation between subjects. "However, the studies did not address the need for a high-SPF standard because variability from lab to lab and sensitivity to experimental error were not evaluated," Brown noted.

In response, Patricia Agin, PhD, Schering-Plough Health-Care Products, said there can be "different interpretations" regarding SPF standards and suggested the use of a control preparation in this type of test "is not a standard in the analytical sense. It is not a classical standard...but it is a control on the laboratory methodology that is really more SPF-independent than it is dependent."

Reacting to a suggestion from Brown that standards be developed for specific sunscreen ranges, Agin maintained such a move "should not be necessary if it functions as a methodology control."

FDA Division of Dermatology & Dental Drug Products Chemistry Team Leader Wilson DeCamp said the agency would be satisfied with any "appropriate method," but "would be less happy with separate methods for two components in combination for SPF 15 products."

Additional methods for sunscreen standards to be considered by the agency may include the high performance liquid chromatography method for combination padimate O (7%) and oxybenzone (3%) for use in SPF 15 sunscreen formulations.

"We have a lot of different methods here that could be developed," DeCamp said. "We don't know if that method will work in an oxybenzone/padimate O combination....The way we find that out is to validate that method in our laboratories." Agin told the agency Schering-Plough plans to submit method validation on the HPLC method.

The agency also addressed existing specifications for solar simulators in the final monograph. Sharon Miller, PhD, Office of Science and Technology, Center for Devices & Radiological Health, noted the requirement that less than 1% of the total energy from solar simulators comes from wavelengths shorter than 290 nm "is inadequate." She continued, "We think that current technology allows something a little tighter."

Under European Cosmetic, Toiletry & Perfumery Association guidelines, the accumulative erythemal radiation is recommended to be less than 1%. However, in the final monograph, FDA recommends a more specific standard, at .1% or .01%. In support of FDA's decision, Miller noted in data submitted to the agency testing more than two dozen solar simulators, all were able to meet the .1% limit and about half could meet the .01% mark.

"I don't think that at this point in time it is practical to go down to .01% due to the limitations of measure implementation currently available and the filters which are available," Schering's Agin responded. "While some solar simulators may meet that level or below, I think that is really serendipitous that they do. Certainly it is not standard."

A .1% limit is "probably more acceptable, but would put us in the position of then being out of sync with the rest of the world who have already enacted the COLIPA specifications," she continued. "I would recommend staying with the COLIPA specifications, however I suppose we could look at the .1%."

FDA also addressed the necessary size cohort for high-SPF tests. Rajagopalan Srinivasan, PhD, Division of Biometrics III team leader, Center for Drug Evaluation & Research, said the agency supports the final rule requirements that a test panel be between 20 and 25 subjects, but noted that with additional information he would consider a larger number if 80% successfully completed a trial.

Finally, Division of OTC Drug Products Team Leader John Lipnicki discussed agency labeling concerns for high-SPF products. Because the concept is difficult to explain on limited label space and in plain language, Lipnicki said consumer understanding of SPF protection may not be accurate.

Lipnicki reiterated that labeling for high-SPF products should convey UVA/UVB proportionality, a sun alert message and clinical relevance based on individual use.

The next FDA/industry meeting, tentatively slated for January, will cover UVA issues. At least one more meeting likely will follow to "tie up loose ends," Office of OTC Drug Products Deputy Director Linda Katz, MD, noted. CTFA VP-Legal and General Counsel Thomas Donegan said two other issues - anti-aging and indications for use - also should be topics of an upcoming meeting.

High-SPF Test Standards Possible Following Modifications - FDA

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