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Considering Test Methods’ Impact on Your Brand

By: Brian Dell, Celsis Analytical Services
Posted: December 7, 2009, from the December 2009 issue of GCI Magazine.

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The technical advances afforded by modern in vitro test methods make it feasible to reduce the number of animals used for testing, refine the historical data provided by in vivo testing methods, replace existing in vivo tests with less expensive, faster in vitro approaches and ultimately deliver a level of reproducibility that cannot be obtained with animal-based test methods. Several in vitro assays have been proven to achieve these goals.

Alternative Testing Primer

A prime example of a proven in vitro alternative to in vivo testing is the use of the Irritection Assay System as a substitute for the animal-based Draize test. Since the 1940s, the Draize test has used ocular and dermal testing in a live rabbit to gauge acute toxicity of beauty products. The Irritection Assay System is a standardized and quantifiable alternative model that detects and predicts the ocular or dermal irritation of potential raw materials or compounds.

For the testing of new products, the Irritection Assay System (a standardized, quantitative in vitro test method) can be specifically applied to evaluate the ocular and/or dermal irritation caused by a test sample. During the testing process, a proprietary protein solution is placed into the wells of a Petri dish to mimic the proteins in the eye, and a membrane disk is placed upon the protein layer in the well. Different volumes or dilutions of test sample are incubated on the membrane, the membrane is observed for deterioration and the remaining material in each well is mixed and tested for the degree of turbidity (a measure of the degree to which transparency is lost) against a standard curve through optical density. Comparison of the density scores allows for the calculation of an irritancy score.

At the early stage of product development, an in vitro assay such as the Irritection format can be used to determine whether or not testing in animals is necessary. In the instance where the Irritection results are positive for irritation or corrosion, there is no need to prove this again in an animal model. The product can either be discarded or it can be reformulated and re-evaluated using the Irritection test format. This practice reduces the total number of animals used in the research phase of product development. Additionally, there is a time and cost savings afforded by the early determination of a product’s irritancy score. Working toward the same decision point in animal studies is significantly more time-consuming and expensive.

Replacement of animal tests occurs when an in vitro assay is deemed acceptable as an equivalent alternative to the animal test. The Corrositex toxicology test is an excellent example of an in vitro assay replacement for animal testing. The test determines the dermal corrosive potential of chemicals and chemical mixtures and replaces a dermal corrosivity rabbit test. In the Corrositex testing system, a glass vial filled with a chemical detection fluid capped by a proprietary bio-barrier membrane, which is designed to mimic the effect of corrosives on living skin. Corrositex measures the time required for a test article to pass through a hydrated collagen matrix and supporting filter membrane. The results, expressed as a break-through time, correlate well with rabbit dermal corrosivity tests. Consequently the Corrositex test has been recognized as an acceptable replacement for the analogous animal test by a number of agencies—including the U.S. Food and Drug Administration.

Improve Reproducibility