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Clinical Safety and Irritation Testing

Clinical Irritation

Nelson Labs Bozeman Skin Technology Center performs clinical evaluations for cumulative skin irritation in accordance with the FDA/CDER Guidance for Industry, Skin Irritation and Sensitization Testing, December 1999.

Study Requirements:

The FDA guidance requires that the drug product and its vehicle (product without active principle) be tested, along with a high-irritancy control material, sodium lauryl sulfate (SLS; also known as sodium dodecyl sulfate, or 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 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 equivalency).

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

Clinical Sensitization

Nelson Labs Bozeman performs sensitization testing by the Modified Draize test in accordance with the FDA/CDER Guidance for Industry, Skin Irritation and Sensitization Testing, December 1999. Additionally, BSL performs testing for skin sensitization to chemicals in natural rubber products with labeling claims of either (1) reduced potential for sensitizing users to rubber chemical additives or (2) 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 (product without active principle) be tested. During the Induction Phase of testing, test materials are applied to skin sites on the upper back of 200 subjects and patched three times per week for three weeks, the same sites of application each time, for a total of nine applications. Patches remain in place for 48 hours at a time on weekdays and 72 hours on the weekends. Evaluation and scoring of skin reactions are performed and recorded at the time of each patch removal.

The Induction Phase is followed by the Rest Phase of two weeks duration, during which 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 and 24, 48, and 72 hours after the patches have been removed for evidence of allergic reaction.

Bovine Corneal Opacity and Permeability (BCOP)

The Bovine Corneal Opacity and Permeability (BCOP) test is an in vitro method to evaluate chemicals inducing serious eye damage or serious eye irritation. This test method is used to classify substances as ocular corrosives and severe irritants, as defined by the U.S. Environmental Protection Agency (EPA), European Union (EU), and the Globally Harmonized System of Classification and Labeling of Chemicals (GHS). This in vitro test reduces the need for laboratory animals to be used in the performance of a standard Draize Test.


The Cytotoxicity Test is designed to evaluate the general toxicity of medical devices and materials. Testing involves extracting devices in a cell culture media and then exposing the extract fluid to mouse fibroblast cells (L929). The cells are allowed to grow in the extract fluid for a specified amount of time before the cells are evaluated using either qualitative or quantitative methods. The test is performed on all medical devices with patient contact, raw materials, and devices undergoing a cleaning validation or residual manufacturing. Learn more about our Cytotoxicity capabilities here.

Test Codes

If you would like to inquire about any of the services listed on this page, please submit the quote request form below.

  • CTX407
    Cytotoxicity: 3D Tissue Model Testing
  • CTX408
    Cytotoxicity: Tissue Test, Cytotoxicity Agar Overlay ISO 10993-5
  • CTX409
    Eye Irritation: Bovine Corneal Opacity and Permeability (BCOP) assay
  • CSK302
    Clinical Skin Care: Irritation
  • CSK303
    Clinical Skin Care: Sensitization, Repeat Insult Patch Test (RIPT) with Induction, Rest and Challenge Phases
  • CSK304
    Clinical Skin Care: Cumulative Irritation, Repeat Insult Patch Test (RIPT) with one Phase

Testing Locations

  • Bozeman, MT, USA

Learn more about our locations and their certifications.

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