Conventional Test Method:

Acute Oral LD50

(formerly OECD TG 401, now deleted as a test method)

Alternative Test Method:

Name & Description:

Neutral Red Uptake (NRU) test with rodent cells (mouse 3T3 fibroblasts)
(3T3 NRU assay)

This is an in vitro basal cytotoxicity assay used to determine starting doses of test compound for two acute oral toxicity test methods (the Up-and-Down Procedure and Acute Toxic Class Method). Neutral red is a dye that is taken up by living cells. If the test compound causes alterations to the cell membranes (e.g., cytotoxicity and/or inhibition of cell growth) then the amount of neutral red taken up by the cells will decrease.

Validation Status:

US: Endorsed as valid by ICCVAM for the purpose of determining starting doses for in vivo acute oral toxicity tests (2006)

Regulatory Status:

US: Recommended by ICCVAM to regulatory agencies for approval (2008)

Effect or Potential Effect on Animal Use:

(part of a tiered testing strategy that results in use of fewer animals)

Information Last Updated:
May 2012