effective dose (ED), 1. on a graded dose-response curve in the laboratory, the dosage of a drug that may be expected to cause a response of the desired magnitude. See also therapeutic dose. 2. in a clinical setting, the dose needed to cause the desired response in a percentage of the people to whom it is given (e.g., an ED50 dosage of a drug is expected to produce a response in 50% of the patients receiving it).
