This document was created by Alex Yartsev (dr.alex.yartsev@gmail.com); if I have used your data or images and forgot to reference you, please email me Dose response: EC50, ED50, LD50 Important definitions Percentage of individuals responding to this dose Therapeutic effect Lethal effect A Toxic effect 100% 50% ED50 TD50 LD50 Dose ED50: Median effective dose The dose required to achieve 50% of the desired response in 50% of the population TD50: Median Toxic dose of 50% for 50%: The dose required to get 50% of the population reporting this specific toxic effect LD50: Median lethal dose The dose required to achieve 50% mortality from toxicity EC50: Half maximum effective concentration The concentration of a drug at which 50% of its maximum response is observed LC50: Half lethal concentration The concentration of a drug at which 50% mortality Ifrom toxicity is observed These are derived from bell curves; i.e in a population of individuals, there will always be variation in drug response – but a majority of them will respond roughly the same way to this drug, and that’s the fat part of the bell curve From “Goodman & Gilman's The Pharmacological Basis of Therapeutics” 11th ed by Brunton et al,and “Basic & Clinical Pharmacology” 11th ed By Katzung et al