Which statement accurately describes MEC and MTC in relation to therapeutic and toxic effects?

Which statement accurately describes MEC and MTC in relation to therapeutic and toxic effects?

• A. MEC is the upper bound for efficacy, MTC is lower bound for toxicity
• B. MEC is the plasma level below which therapeutic effects will not occur; MTC is the level at which toxicity occurs
• C. MEC equals MTC
• D. MEC and MTC relate to absorption rate

Answer: (B)

The main idea is thresholds that separate efficacy from toxicity. MEC, the minimum effective concentration, is the lowest plasma level at which therapeutic effects begin. If the concentration is below this, you don’t get the desired effect. MTC, the minimum toxic concentration, is the level at which toxicity starts to appear. Between these two values sits the therapeutic window—enough drug to be effective but not so high as to cause toxicity. So describing MEC as the lower bound for efficacy and MTC as the level where toxicity occurs correctly captures their roles. The other statements either misstate the bounds or confuse these concepts with absorption.

The main idea is thresholds that separate efficacy from toxicity. MEC, the minimum effective concentration, is the lowest plasma level at which therapeutic effects begin. If the concentration is below this, you don’t get the desired effect. MTC, the minimum toxic concentration, is the level at which toxicity starts to appear. Between these two values sits the therapeutic window—enough drug to be effective but not so high as to cause toxicity. So describing MEC as the lower bound for efficacy and MTC as the level where toxicity occurs correctly captures their roles. The other statements either misstate the bounds or confuse these concepts with absorption.