The metabolism of xenobiotics is often divided into three phases: modification, conjugation, and excretion. These reactions act in concert to detoxify xenobiotics and remove them from cells.

There are four ways to quantify drug responses.1. IC50: Half maximal inhibitory concentration2. EC50: Half maximal effective concentration3. GI50: Half maximal growth inhibition concentration4. LD50: Lethal dose 50All four refer to the concentration of a drug that satisfies certain conditions, and the conditions have different meanings. Some view IC50 and GI50 as the same thing, so let's look at..

Efficacy: Efficacy indicates the maximum intensity of response to a drug, eg. if the intensity of drug A is higher than drug B, then drug A is more efficacious than drug B ED50 (effective dose-50%) is the dose or drug that gives rise to the designated response in 50% of the subjects or produced a 50% response. ED50 is easier to measure than maximum effect and is used to determine the efficacy Si..