The size or the gap between ED and LD for a given drug is referred to as the:

• A. A Intoxication ratio
• B. B Safety or therapeutic margin
• C. C Neurotransmitter ratio
• D. D Psychoactivity ratio

Answer: (B)

The main idea here is the drug’s safety margin—the space between the dose that produces the desired effect (ED) and the dose that can cause harm (LD). This gap shows how forgiving a drug’s dosing is: a larger margin means you can administer a bigger amount before toxicity occurs, making the drug safer to use. People often express this concept as the therapeutic index, which is the ratio of the toxic dose to the effective dose, but the simple gap itself is what we call the safety or therapeutic margin. The other terms listed don’t describe this relationship; they aren’t standard ways to refer to the distance between effective and lethal doses.