Pre-validation

Pre-validation may involve multiple laboratory studies to optimize and standardize the protocol, and develops preliminary data on reproducibility within a single laboratory (e.g, performance criteria). Depending upon the level of refinement required for the protocol, pre-validation can be a very time consuming stage of the validation process.

Several different types of studies may be needed in pre-validation, including:

• Optimization studies to choose optimum conditions for the assay, refine the protocol, and eliminate duplicative or non-sensitive endpoints.
• Special studies to resolve unknown issues related to protocol design.
• Studies that use a small number of chemicals to demonstrate that the protocol can provide a measure of a relevant endpoint.
• Multi-chemical studies to determine relevance:
• Studies should state expectations for each chemical;
• Studies should be conducted using chemicals with specific mechanisms of action; and
• Studies should generally use 8 to 12 chemicals for in vivo screens, perhaps more for in vitro screens, and fewer for Tier 2 studies.

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