Principles of EC50, ED50, pD2 and pA2 Values of Drugs

The effects of most drugs depend on the dose that is provided to the subject. In line with this, we have a concept called "dose descriptors", which takes into account the relationship between a particular dose of a drug and the corresponding effect produced by it. The commonly used "dose descriptors" include EC50 (half maximal effective concentration), LC50 (median lethal concentration), ED50 (median effective dose), TD50 (median toxic dose), LD50 (median lethal dose), etc. This chapter attempts to elucidate the basics of these determinants. In addition, we will also look at the drug toxicity studies that are commonly performed for any new drug.