Which term is the ratio of lethal dose to effective dose?

Which term is the ratio of lethal dose to effective dose?

• A. Therapeutic index
• B. Margin of safety
• C. Pharmacokinetics
• D. Preclinical testing

Answer: (A)

Safety margin for a drug is captured by the therapeutic index, which is the ratio of the dose that can be lethal to half of those exposed to it to the dose that produces the desired therapeutic effect in half of those exposed. In other words, it compares the lethal dose (LD50 or TD50) to the effective dose (ED50). A larger ratio means a wider safety buffer between an effective dose and a lethal one, indicating the drug is safer to use across a range of doses. The term described here is the therapeutic index. Margin of safety is related but not the exact ratio highlighted in the question, and pharmacokinetics or preclinical testing refer to different concepts entirely.

Safety margin for a drug is captured by the therapeutic index, which is the ratio of the dose that can be lethal to half of those exposed to it to the dose that produces the desired therapeutic effect in half of those exposed. In other words, it compares the lethal dose (LD50 or TD50) to the effective dose (ED50). A larger ratio means a wider safety buffer between an effective dose and a lethal one, indicating the drug is safer to use across a range of doses. The term described here is the therapeutic index. Margin of safety is related but not the exact ratio highlighted in the question, and pharmacokinetics or preclinical testing refer to different concepts entirely.