This article provides insufficient context for those unfamiliar with the subject. (October 2009)
Up-and-down procedure (or method) is an alternative to the LD acute 50 toxicity test.  
It requires fewer animals to achieve similar accuracy as the LD
50 test. However, the U.S. Food and Drug Administration has begun to approve non-animal alternatives.   
References [ edit ]
^ Lipnick, RL; Cotruvo, JA; Hill, RN; Bruce, RD; Stitzel, KA; Walker, AP; Chu, I; Goddard, M; et al. (1995). "Comparison of the up-and-down, conventional LD50, and fixed-dose acute toxicity procedures". . Food and chemical toxicology 33 (3): 223–31. PMID 7896233. doi: 10.1016/0278-6915(94)00136-C.
^ Lichtman, A (1998). "The up-and-down method substantially reduces the number of animals required to determine antinociceptive ED50 values". Journal of Pharmacological and Toxicological Methods. 40 (2): 81–5. PMID 10100496. doi: 10.1016/S1056-8719(98)00041-0.
^ Acute Oral Toxicity (AOT) Up-And-Down-Procedure
^ "Allergan Receives FDA Approval for First-of-Its-Kind, Fully in vitro, Cell-Based Assay for BOTOX® and BOTOX® Cosmetic (onabotulinumtoxinA)". Source: Allergan, Inc. News Provided by Acquire Media. 24 June 2011 . Retrieved . 2011-06-26
^ "In U.S., Few Alternatives To Testing On Animals". . 12 April 2008 Washington Post . Retrieved . 2011-06-26