Which term is used for a drug that enhances the effects of another drug?

The term that refers to a drug that enhances the effects of another drug is "synergist." In pharmacology, a synergistic effect occurs when two or more substances work together to produce a more powerful effect than they would individually. This means that when a synergist is combined with another drug, the total effect is greater than the sum of their individual effects. This principle is important in therapy as it can help in maximizing the efficacy of treatment while potentially minimizing dosages and side effects.

The other terms have distinct meanings in the context of drug interactions: an antagonist inhibits or counteracts the effects of another drug, while an inhibitor typically decreases the activity of an enzyme or a receptor, leading to a reduced effect of a drug. An agonist, on the other hand, activates or mimics the action of a receptor, which does not necessarily involve enhancing the effect of another drug. Thus, "synergist" is the most accurate term for describing a drug that enhances the effects of another.