Potentiation refers to which of the following?

• A. Antagonism between drugs
• B. Reduced effect when combined
• C. Enhancement of the effect of one drug by another drug
• D. No interaction

Answer: (C)

Potentiation is when one drug increases the effect of another drug, often with the potentiating agent having little or no effect on its own. A classic example is a drug that alters the way another drug is processed in the body, such as slowing its elimination so the other drug stays in the system longer and has a greater effect. For instance, probenecid can raise penicillin levels by reducing its renal excretion, thereby enhancing penicillin’s impact. This is different from antagonism, where one drug diminishes the effect of another, and from no interaction, where the drugs don’t affect each other. Potentiation can occur even if the potentiating drug contributes little pharmacologic effect by itself.