ED50 is defined as which of the following?

ED50 is defined as which of the following?

• A. The dose required to produce the required effect in 50% of patients receiving the drug
• B. The dose that produces death in 50% of patients
• C. The dose that produces maximum effect in 50% of patients
• D. The dose that produces 90% of effect

Answer: (A)

ED50 is the median effective dose—the amount of drug needed to achieve the defined therapeutic effect in 50% of the population. This measure comes from the dose–response curve and reflects potency: drugs with lower ED50 reach the desired effect at smaller doses. It’s distinct from toxicity (LD50, lethal dose for 50% of subjects) and from the dose that yields 90% of the effect (ED90). So the statement that the dose required to produce the defined effect in half of the patients best describes ED50.

ED50 is the median effective dose—the amount of drug needed to achieve the defined therapeutic effect in 50% of the population. This measure comes from the dose–response curve and reflects potency: drugs with lower ED50 reach the desired effect at smaller doses. It’s distinct from toxicity (LD50, lethal dose for 50% of subjects) and from the dose that yields 90% of the effect (ED90). So the statement that the dose required to produce the defined effect in half of the patients best describes ED50.