TI true statement?

TI true statement?

• A. TI Is The Ratio Of Toxic Dose To Therapeutic Dose
• B. TI Is The Time To Onset
• C. TI Is The Difference Between Minimum Therapeutic And Minimum Toxic Concentrations
• D. TI Is The Volume Of Distribution

Answer: (C)

The key idea being tested is what the therapeutic index (TI) actually measures. TI expresses the safety margin of a drug as a ratio, specifically the dose that causes toxicity in 50% of individuals divided by the dose that produces a therapeutic effect in 50% (TD50/ED50). Expressed this way, TI shows how much higher the toxic dose is compared with the effective dose—the larger the TI, the safer the drug generally is. The option that defines TI as a ratio of a toxic dose to a therapeutic dose aligns with this standard definition and thus correctly describes TI. In contrast, describing TI as the difference between the minimum therapeutic concentration and the minimum toxic concentration points to the therapeutic window (or therapeutic range), which is a range of concentrations where the drug is effective without being toxic, not the TI itself. Time to onset and volume of distribution relate to how quickly a drug acts or how it distributes in the body, not to the safety margin captured by TI.

The key idea being tested is what the therapeutic index (TI) actually measures. TI expresses the safety margin of a drug as a ratio, specifically the dose that causes toxicity in 50% of individuals divided by the dose that produces a therapeutic effect in 50% (TD50/ED50). Expressed this way, TI shows how much higher the toxic dose is compared with the effective dose—the larger the TI, the safer the drug generally is.

The option that defines TI as a ratio of a toxic dose to a therapeutic dose aligns with this standard definition and thus correctly describes TI. In contrast, describing TI as the difference between the minimum therapeutic concentration and the minimum toxic concentration points to the therapeutic window (or therapeutic range), which is a range of concentrations where the drug is effective without being toxic, not the TI itself. Time to onset and volume of distribution relate to how quickly a drug acts or how it distributes in the body, not to the safety margin captured by TI.