A larger TI value correlates with which of the following?

A larger TI value correlates with which of the following?

• A. Lower drug safety
• B. More variability in response
• C. Higher drug safety
• D. Narrower safety margin

Answer: (C)

Therapeutic index measures the safety window between the dose that produces the therapeutic effect and the dose that causes toxicity. A larger TI means this gap is bigger, so you can achieve the desired effect without approaching toxic levels, which equates to higher drug safety. For example, if the effective dose is 10 mg and the toxic dose is 200 mg, the TI is 20—a wide safety margin. If those values were closer, the TI would be smaller and safety would be reduced. This concept doesn’t describe variability in response, and a larger TI does not indicate a narrower safety margin; it indicates a wider, safer margin between efficacy and toxicity.

Therapeutic index measures the safety window between the dose that produces the therapeutic effect and the dose that causes toxicity. A larger TI means this gap is bigger, so you can achieve the desired effect without approaching toxic levels, which equates to higher drug safety. For example, if the effective dose is 10 mg and the toxic dose is 200 mg, the TI is 20—a wide safety margin. If those values were closer, the TI would be smaller and safety would be reduced.

This concept doesn’t describe variability in response, and a larger TI does not indicate a narrower safety margin; it indicates a wider, safer margin between efficacy and toxicity.