Up-and-down procedure

Up-and-down procedure (or method) for toxicology tests in medicine is an alternative to the LD₅₀ test, in which animals are used for acute toxicity testing. It requires fewer animals to achieve similar accuracy as the LD₅₀ test because animals are dosed one at a time. 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. The U.S. Food and Drug Administration has begun to approve non-animal alternatives.

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.