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Frequency distribution curves and quantal concentration-effect and dose-effect curves. A. Frequency distribution curves. An experiment was performed on
100 subjects, and the effective plasma concentration that produced a quantal response was determined for each individual. The number of subjects who
required each dose was plotted, giving a log-normal frequency distribution (purple bars). The normal frequency distribution, when summated, yields the
cumulative frequency distribution—a sigmoidal curve that is a quantal concentration-effect curve (red bars, red line). B. Quantal dose-effect curves.
Animals were injected with varying doses of a drug and the responses were determined and plotted. The calculation of the therapeutic index, the ratio of
the LD50 to the ED50, is an indication of how selective a drug is in producing its desired effects relative to its toxicity. See text for additional explanation.
Source: Pharmacodynamics: Molecular Mechanisms of Drug Action, Goodman and Gilman's Manual of Pharmacology and Therapeutics, 2e
Citation: Hilal-Dandan R, Brunton LL. Goodman and Gilman's Manual of Pharmacology and Therapeutics, 2e; 2016 Available at:
http://mhmedical.com/ Accessed: May 04, 2017
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