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National Psoriasis Foundation For further information:
Voice: (503) 244-7404
Fax: (503) 245-0626

Skin-Cap: the NPF's investigation

[First Posted 4/19/99]

Note: This article is from the Mar/Apr 2000 Bulletin, the bi-monthly national newsletter of the National Psoriasis Foundation©.

o Background on Skin-Cap

o Message from NPF President & CEO Gail M. Zimmerman

o Q&A about the NPF's Skin-Cap Investigation

o Comments or questions? Contact the NPF

Background on Skin-Cap

As many of you may know, Skin-Cap was a popular over-the-counter (OTC) spray product that claimed its only active ingredient was zinc pyrithione, an ingredient approved by the U.S. Food and Drug Administration (FDA) for OTC products in treating dandruff.

Yet, Skin-Cap was marketed in the U.S. as a psoriasis treatment. The FDA removed it from the consumer market in August 1997 because the FDA determined that it contained a prescription medication that was not listed on the label. Congressional law requires all medications containing prescription ingredients be approved and regulated by the FDA to ensure that consumers are aware of the benefits and side effects of the drugs.

Cheminova, the Spanish manufacturer of Skin-Cap, did not disclose that its product contained a prescription ingredient nor did the company submit an application to the FDA for the product's approval for sale in the U.S.

Testing had indicated that the product contained clobetasol propionate, a prescription steroid medication that is very effective in clearing psoriasis, but which can also cause serious long-term health problems if it is not used appropriately. More than 100 Skin-Cap users told the NPF that the product caused severe adverse reactions, and several dermatologists reported similar experiences in some of their Skin-Cap patients, who in some cases required hospitalization.

At the same time, hundreds of people who used Skin-Cap told the NPF this was the most effective product they had ever used, especially for the scalp. Many of them also felt that Skin-Cap worked better than the available clobetasol propionate products (including prescription brand Temovate). These people said they had not observed any problems in using Skin-Cap.

Because of the overwhelming interest in this issue, both from people who liked Skin-Cap and wanted it back, and from people who were concerned about its side effects, the NPF decided to investigate the composition of Skin-Cap and what might be necessary to bring it back to the consumer market.

We would like to share with you the results of that investigation -- what we did and what we learned. An overview is presented in the letter below and the details are provided in the accompanying questions and answers.

Message from Gail M. Zimmerman,
NPF Chairman & CEO

Dear NPF Members:

Gail M. Zimmerman

The NPF Board of Trustees and I recognize that many people with psoriasis have a strong desire to see Skin-Cap made available to them. And we believe that people with psoriasis have a right to make educated decisions about their treatment, with as much information as possible. That belief is a central part of the NPF mission.

That's why we initiated our Skin-Cap investigation more than two years ago, to learn what might be done to get someone to bring it back to the market, and, toward that end, to possibly identify any additional unlisted ingredients. We formulated a strategy to address this very complicated issue as effectively as we could with the limited resources we had available.

As a result of our research, we believe that clobetasol propionate was the primary reason for Skin-Cap's effectiveness. We tested for several other potentially active ingredients that various investigators reported might be in the product, but we did not find them.

Our tests also revealed that there are many additional ingredients in the product. It is possible that one or more of these ingredients might enhance the steroid's effectiveness. We have concluded at this point in our investigation that further testing and analysis of this product would require the much larger resources of a pharmaceutical company.

We brought this issue to two companies that seriously considered the product, and one may be pursuing testing at this time. We will continue to discuss this issue with the pharmaceutical industry and solicit interest in further testing.

We appeal to Cheminova to disclose the full list of Skin-Cap ingredients and to go through the established legal channels to seek approval of the product and re-introduction to the U.S. market. An FDA representative has advised us the agency is willing to review an application for approval of a Skin-Cap-type product.

Only Cheminova knows the precise ingredients of Skin-Cap. If the company continues to show no interest in pursuing legal channels of approval, someone else would have to conduct an expensive full-scale analysis of Skin-Cap to identify all of the ingredients.

We realize many of you are disappointed that Skin-Cap is not available. At this point in time, we don't know if it will ever be available. We understand that our findings are not likely to satisfy everyone, and indeed we are not satisfied. However, we hope that in reading this article you will understand the issues with which we have struggled and the limitations we have faced in conducting this investigation.

We are looking at opportunities to fund research into better, safer and more universal treatments for psoriasis, beyond topical steroids. We will have a comprehensive research plan in place by June which will outline our strategies for funding future basic and clinical research in psoriasis and psoriatic arthritis. We will be sharing the goals and objectives of this plan with you in the months ahead.

If you have any further questions, or would like copies of our test results, please call us at (503) 244-7404. (We may have to charge for duplication, depending on the requested materials.) You may ask for Corrine Kail at extension 16, or e-mail us at

We welcome any comments. I would like to personally thank you for your membership support, which is so important to us.

Gail M. Zimmerman
President & CEO

Q&A about the NPF's Skin-Cap investigation

What would be required to bring a Skin-Cap product back to the U.S. market?

The most obvious way to get Skin-Cap back on the U.S. market would be for Cheminova to submit the product to the FDA for approval, which would involve clinical trials to demonstrate that it works and that it is safe.

In lieu of that, another pharmaceutical company could try to bring a similar product to market, but this would require knowledge of the product's exact ingredients. As no one other than Cheminova knows exactly what is in Skin-Cap, the product would have to be reverse engineered to identify all of its ingredients.

Tests performed by the NPF and others indicate that Skin-Cap is a complex mixture of unknown substances. The independent laboratory that assisted us with our Skin-Cap testing said that to reverse engineer the product and figure out exactly what was in it would require an investment of at least one year and several hundred thousand dollars -- money the NPF does not have.

Even if the product's ingredients could be identified, it would still need to be a prescription medication (due to the clobetasol propionate), and it would require millions of dollars to conduct the necessary clinical trials to prove its safety.

Because the testing and development process that is required for prescription products can take 5-7 years, at a minimum expense of $20 million, a company would have to be convinced that the product would be very promising to warrant such an investment.

It is clear that because Skin-Cap is such a complicated substance, a company wanting to try to bring a Skin-Cap-type product to the market would face millions of dollars in costs, years of development and a very uncertain outcome.

Why did the NPF test Skin-Cap?

The NPF wanted to try and figure out some basic answers about Skin-Cap for two reasons: our members' extraordinary interest in this product, and the manufacturer's apparent unwillingness to take the product through the proper legal channels. Our members, Board of Trustees and medical advisors, many of whom witnessed the effectiveness of Skin-Cap on their patients, felt there were two key questions:

  1. Was it possible to identify additional unlabeled ingredients in Skin-Cap that might help explain why it seemed to work so well for some people, or to learn about any additional safety hazards?

  2. What might be done to get someone to bring Skin-Cap back to the market legitimately?

What were the steps in the NPF's investigation?

We gathered data from Skin-Cap users, members, physicians whose patients used Skin-Cap, and other researchers. We requested all records of the FDA's testing of Skin-Cap, and had those documents analyzed by a chemist at an independent, nonprofit laboratory.

We hired that independent laboratory to test for clobetasol propionate and several additional ingredients. We explored the possibility and the costs for someone to reverse engineer Skin-Cap, and we researched the steps that would be required to bring such a product to market legally.

We attempted to interest several pharmaceutical companies in researching Skin-Cap and bringing it, or something similar, back to the market.

What has the NPF learned through its investigation?

Results of Skin-Cap testing
Performed for the NPF by an independent laboratory
Ingredient Results (was it found)
Clobetasol propionate,
superpotent topical steroid
Retinoids, tretinoin, isotretinoin,
other vitamin A analogues
Cresol, potent coal
tar-like substance
Isopropyl myristate,
penetration enhancer
Yes, tentatively identified
Butane and isobutane,
standard propellant in spray products
Yes, tentatively identified
Analysis also indicates the presence of many other unknown, unlabeled ingredients.

  • Most Skin-Cap users we heard from found the treatment very helpful, but many people experienced serious side effects. We gathered extensive case histories, both from hundreds of people who were extremely satisfied using Skin-Cap to treat their psoriasis, and from more than one hundred people -- including many children -- who experienced serious side effects from the product, including severe pustular flares that required hospitalization.

  • Skin-Cap is a complex substance with many, many ingredients. We tested cans of Skin-Cap from six different lots and found significant amounts of the superpotent topical steroid clobetasol propionate, confirming the findings of other laboratories.

    We also checked for several other ingredients that various people and experts had speculated might be in the product. Those ingredients included retinoids (tretinoin, isotretinoin and other vitamin A derivatives); volatile compounds such as cresol; and propellants, penetration enhancers (which help medications get through the skin more effectively) and different kinds of alcohols. Tests revealed few of the specific ingredients we were looking for, but they did clearly demonstrate that Skin-Cap was a very complex substance with many unknown ingredients.

  • Skin-Cap does not seem to be absorbed through the skin better than similar steroid products. We consulted with a pharmaceutical company that tested Skin-Cap against other topical steroid products. Initial results determined that Skin-Cap does not seem to be absorbed through the skin better than similar steroid products.

    (These absorption tests were limited because they were performed on human cadaver skin. Skin-Cap could not be tested on humans because clinical trial regulations prohibit product testing on live human volunteers when the ingredients are unknown.) This does not help explain why so many people felt that Skin-Cap worked better than topical steroids, including clobetasol propionate, that they had used before.

Are there products on the market similar to Skin-Cap?

We understand that there are a number of companies marketing Skin-Cap "clones" through the mail and the Internet. Some of these companies say their products contain zinc pyrithione as the only active ingredient. (Zinc pyrithione, which is readily available to treat dandruff, has not been shown effective for psoriasis treatment.)

Most companies advise that their product be compounded with a steroid medication through a physician's prescription. (Skin-Cap is not approved for sale in this country, although we have been told that some people obtain it illegally through the mail or the Internet.)

We do not know about the safety, effectiveness or ingredients of any of these products, and we have heard little from people who have used them.

Why are clobetasol propionate products legal but Skin-Cap is not?

All companies with available prescription clobetasol propionate products (such as Temovate and others) have conducted all of the necessary tests and clinical trials required by law to demonstrate safety and effectiveness and have identified all of their product's ingredients.

How do Skin-Cap or "clone" distributors get my name, address or phone number to continue to contact me?

If you ever made an inquiry or purchased Skin-Cap, the distributors still have your contact information. Beyond that, the NPF does not know how your name would be obtained by these marketing companies. The NPF's membership list is confidential, and we never release contact information to any outside party.

Comments or questions? Contact the NPF

The NPF welcomes all comments and questions about this article or the Skin-Cap investigation. You can contact the NPF:

  • By phone, (503) 244-7404 (ask for Corrine Kail at ext. 16);
  • By fax, (503) 245-0626;
  • By e-mail,

See Also: | Skin-Cap Q&A;, August 1997 | NPF Services | NPF Membership |