Ld50

In preclinical studies, the LD50 is the median lethal dose—the dose of a drug that produces death in 50 percent of the experimental animals tested. The LD50 can be estimated from a dose-effect curve, where the concentration of the drug is plotted against the percentage of animals that die. The ratio of the LD50 to the ED50 (the median effective dose) indicates the therapeutic index of a drug for that effect and suggests how selective the drug is in producing its desired effects. In clinical studies, the concentration of the drug required to produce toxic effects can be compared to the concentration required for therapeutic effects in the population to esimate the clinical therapeutic index.

(SEE ALSO: Research: Animal Model)

BIBLIOGRAPHY

GILMAN, A. G., ET AL., (EDS.). (1990). Goodman and Gilman's the pharmacological basis of therapeutics, 8th ed. New York: Pergamon.

NICK E. GOEDERS