Dose-response relationships. A Dose-response relationships. A. The LD50 of a compound is determined experimentally, usually by administration of the chemical to mice or rats (orally or intraperitoneally). The midpoint of the curve representing percentage of population responding (response here is death) versus dose (log scale) represents the LD50, or the dose of drug that is lethal in 50% of the population. The LD50 values for both compounds are the same (~10 mg/kg); however, the slopes of the dose-response curves are quite different. Thus, at a dose equal to one-half the LD50 (5 mg/kg), fewer than 5% of the animals exposed to compound Y would die, but about 25% of the animals given compound X would die. B. Depiction of ED and LD. The crosshatched area between the ED91 (10 mg/kg) and the LD9 (100 mg/kg) gives an estimate of the margin of safety. Source: Drug Toxicity and Poisoning, Goodman & Gilman's: The Pharmacological Basis of Therapeutics, 13e Citation: Brunton LL, Hilal-Dandan R, Knollmann BC. Goodman & Gilman's: The Pharmacological Basis of Therapeutics, 13e; 2017 Available at: http://accessbiomedicalscience.mhmedical.com/DownloadImage.aspx?image=/data/books/2189/goodman13_ch4_f001-1.png&sec=166183166&BookID=2189&ChapterSecID=166183158&imagename= Accessed: December 17, 2017 Copyright © 2017 McGraw-Hill Education. All rights reserved