Use the drop-down menus to select the answer that completes each sentence. During the tests that are performed to test the potential dosing of a drug, researchers will determine the , which indicates how much of the drug is needed to be effective. The margin of safety, or , is a ratio of the safe dose and the effective dose; a large margin of safety is the best. The frequency of a drug should be determined based on the of the drug, which can indicate how quickly the drug is excreted from the body.