Clinical Safety and Irritation Testing

Cumulative Irritation Evaluations

Nelson Labs Bozeman performs clinical evaluations in its Skin Technology Center for cumulative skin irritation in accordance with the guidance for industry titled “Skin Irritation and Sensitization Testing of Generic Transdermal Drug Products” (December 1999) controlled by the Center for Drug Evaluation and Research (CDER), part of the U.S. Food and Drug Administration (FDA).

Study Requirements:

The FDA guidance requires that a drug product and its vehicle be tested, along with a high-irritancy control material, sodium lauryl sulfate (SLS), also known as sodium dodecyl sulfate (SDS), and a low-irritancy control material, 0.9% saline, by applying small quantities to a single site on the skin of the upper back of 30 or more subjects each day for 21 days and occlusively patching each site while the applied material is wet.

If the testing is for an abbreviated new drug application (ANDA), in which bioequivalency data are necessary, a fifth material—the so-called innovator patch—is also tested, and the outcome for the test material is compared with that for the innovator, i.e. the product already approved to market to which the test material claims to be equivalent.

The degree of irritation at the sites is scored for degree of erythema, vesiculation, and peripheral extension each day prior to reapplication of the materials.

Sensitization Testing

Nelson Labs Bozeman performs sensitization testing using the Modified Draize test in accordance with the guidance for industry titled “Skin Irritation and Sensitization Testing of Generic Transdermal Drug Products” (December 1999) controlled by the Center for Drug Evaluation and Research (CDER), part of the U.S. Food and Drug Administration (FDA). Nelson Labs Bozeman also performs testing for skin sensitization to chemicals in natural rubber products with labeling claims of either reduced potential for sensitizing users to rubber chemical additives or reduced potential for causing reaction in individuals sensitized to rubber chemical additives (FDA 1999).

Test Requirements:

The method requires that the product and its vehicle be tested. During the induction phase of testing, test materials are applied to skin sites on the upper back—the same sites of application each time—of 200 subjects and patched three times per week for three weeks, for a total of nine applications. Patches remain in place for 48 hours at a time on weekdays and 72 hours on weekends. Evaluation and scoring of skin reactions are performed and recorded at the time of each patch removal.

The induction phase is followed by a rest phase of two weeks, during which time no product applications are performed.

Then, during the challenge phase, materials are applied to new skin sites on the back and patched for a 48-hour period of exposure, at the end of which patches are removed. The challenge sites are evaluated 30 minutes after the patches have been removed and again 24, 48, and 72 hours after for evidence of allergic reaction.

Test Codes

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