Up-and-down procedure

Up-and-down procedure ^[1] (or method) for toxicology tests in medicine is an alternative to the LD₅₀ test, in which animals are used for acute toxicity testing. ^{[2] [3]} It requires fewer animals to achieve similar accuracy as the LD₅₀ test because animals are dosed one at a time. ^[4] If the first animal survives, the dose for the next animal is increased; if it dies, the dose is decreased. It is usual to observe each animal for 1 or 2 days before dosing the next animal, however, surviving animals should be monitored for 7 days in case of delayed death. The up-and-down method is not recommended where deaths beyond 2 days are the norm. ^[5] The US EPA provides a statistical program to calculate the oral LD₅₀ and 95% Confidence Limits called AOT425StatPgm ^[6] . This program will notify the user when a stopping criteria has been met, while being able to generate statistically valid LD₅₀, using fewer animals. ^[1] The U.S. Food and Drug Administration has begun to approve non-animal alternatives. ^{[7] [8]}

References

1. "Test No. 425: Acute Oral Toxicity: Up-and-Down Procedure". OECD. 2022-06-29. Retrieved 2025-08-04.
2. Lipnick, R.L.; Cotruvo, J.A.; Hill, R.N.; Bruce, R.D.; Stitzel, K.A.; Walker, A.P.; Chu, I.; Goddard, M.; Segal, L.; Springer, J.A.; Myers, R.C. (March 1995). "Comparison of the up-and-down, conventional LD50, and fixed-dose acute toxicity procedures". Food and Chemical Toxicology. 33 (3): 223–231. doi:10.1016/0278-6915(94)00136-c. PMID   7896233.
3. Lichtman, Aron H (August 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): 81–85. doi:10.1016/s1056-8719(98)00041-0. PMID   10100496.
4. "Acute Oral Toxicity Up-And-Down-Procedure". US EPA. 2 June 2015.
5. Bruce, R (February 1985). "An up-and-down procedure for acute toxicity testing". Fundamental and Applied Toxicology. 5 (1): 151–157. doi:10.1016/0272-0590(85)90059-4. PMID   3987991.
6. "Acute Toxicity Six-Pack | MB Research Laboratories". 2022-06-21. Retrieved 2025-08-04.
7. "Allergan Receives FDA Approval for First-of-Its-Kind, Fully in vitro, Cell-Based Assay for BOTOX® and BOTOX® Cosmetic (onabotulinumtoxinA)" (Press release). Allergan. June 24, 2011. Retrieved May 19, 2020.
8. Gaul, Gilbert M. (12 April 2008). "In U.S., Few Alternatives To Testing On Animals". The Washington Post.

Further reading

• Dixon, W. J. (1965). "The Up-and-Down Method for Small Samples". Journal of the American Statistical Association. 60 (312): 967–978. doi:10.1080/01621459.1965.10480843. JSTOR   2283398.
• Brownlee, K. A.; Hodges, J. L.; Rosenblatt, Murray (1953). "The Up-and-Down Method with Small Samples". Journal of the American Statistical Association. 48 (262): 262–277. doi:10.1080/01621459.1953.10483472. JSTOR   2281287.
• Dixon, W.J. (March 1991). "Staircase bioassay: The up-and-down method". Neuroscience & Biobehavioral Reviews. 15 (1): 47–50. doi:10.1016/s0149-7634(05)80090-9. PMID   2052197. S2CID   39936998.