In pharmacology, what type of drug interaction occurs when two drugs produce an additive effect?

• A. Synergistic interaction
• B. Potentiation
• C. Additive interaction
• D. Antagonistic interaction

Answer: (C)

Additive interaction: when two drugs are given together and their effects simply add up, so the total effect equals the sum of the individual effects. If Drug A produces a certain amount of effect and Drug B produces another, the combined effect is roughly A plus B. This is different from a synergistic interaction, where the combination produces more than the sum of the parts, and from antagonistic interaction, where one drug reduces the effect of the other. Potentiation is when one drug enhances the effect of another, often without contributing its own effect. So, when the question describes an additive effect, the best way to describe it is an additive interaction.