Which term best describes an interaction where two drugs together produce an effect greater than the sum of their individual effects?

Which term best describes an interaction where two drugs together produce an effect greater than the sum of their individual effects?

• A. Antagonistic
• B. Additive
• C. Synergistic
• D. Neutral

Answer: (C)

This describes a synergistic interaction, where combining two drugs produces a total effect greater than the sum of their separate effects. In other words, the drugs amplify each other’s impact rather than just adding up their individual responses. To see why, think of each drug’s effect as a number. If one drug gives a certain amount of response and the other adds its own amount, an additive interaction would equal the simple sum. But when the combined effect exceeds that sum, that extra boost is synergy. Mechanisms behind this can be pharmacodynamic, where the drugs boost each other’s action at the same target or pathway, or pharmacokinetic, where one drug increases the exposure or activity of the other. This is different from antagonistic interactions, where one drug diminishes the effect of the other; and from a purely additive interaction, where the combined effect equals the sum. Neutral would imply no interaction at all. So, the term that fits is synergy, because it specifically describes an effect bigger than the sum of the parts.

This describes a synergistic interaction, where combining two drugs produces a total effect greater than the sum of their separate effects. In other words, the drugs amplify each other’s impact rather than just adding up their individual responses.

To see why, think of each drug’s effect as a number. If one drug gives a certain amount of response and the other adds its own amount, an additive interaction would equal the simple sum. But when the combined effect exceeds that sum, that extra boost is synergy. Mechanisms behind this can be pharmacodynamic, where the drugs boost each other’s action at the same target or pathway, or pharmacokinetic, where one drug increases the exposure or activity of the other.

This is different from antagonistic interactions, where one drug diminishes the effect of the other; and from a purely additive interaction, where the combined effect equals the sum. Neutral would imply no interaction at all.

So, the term that fits is synergy, because it specifically describes an effect bigger than the sum of the parts.