median effective dose
Quick Summary
The median effective dose, or ED50, is a pharmacology term representing the dose of a drug that produces a specific effect in 50 percent of a test population. This dose is typically 50 percent of the maximum obtainable effect.1
ED50 values are useful for comparing the potency of different drugs that have similar effects. When measuring an all-or-nothing response, the ED50 indicates the dose that elicits a response in half of the individuals tested.1
A related concept is the median lethal dose (LD50), which is the dose that causes mortality in 50 percent of a test group, often used as a rough estimate of drug toxicity. The ratio of LD50 to ED50 is known as the therapeutic index, indicating a drug's margin of safety. A narrower therapeutic index suggests a higher likelihood of unwanted side effects.12
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