When two drugs' effects are less than the sum of their individual effects, this is referred to as?

When two drugs are combined and their overall effect is less than the sum of their individual effects, this phenomenon is known as antagonism. In this context, antagonism occurs when one drug counteracts or diminishes the effect of another drug, leading to a reduced overall effectiveness when they are used together. This can happen when the mechanisms of action of the two drugs interfere with each other, preventing them from achieving their full therapeutic potential.

In contrast, synergism refers to an interaction where the combined effect of the drugs is greater than the sum of their individual effects. Additive effects mean that the total effect is equal to the sum of the effects of the individual drugs, which is not applicable in this scenario. Displacement effects typically refer to situations where one drug displaces another from protein binding sites, potentially leading to increased free concentrations of the displaced drug but does not directly relate to the overall effect being less than the sum of individual actions.

Thus, the appropriate term for the described situation is antagonism, as it specifically captures the scenario where the combined drug effects do not achieve the anticipated therapeutic results.