Which term describes a weaker effect when more than one drug is taken?

• A. Antagonism
• B. Systemic Effect
• C. Tolerance
• D. Cumulation

Answer: (A)

Antagonism is when the combined effect of two drugs is weaker than what either would produce alone because they interfere with each other’s actions. This can happen when they compete for the same receptor sites or one drug blocks the action of the other at its target, leading to a diminished overall response. A familiar example is when an antagonist blocks opioid receptors, reducing or reversing the opioid’s effects. This contrasts with tolerance (a decreased response to repeated use of the same drug), cumulation (drug buildup in the body with continued dosing), and systemic effect (how a drug spreads and acts throughout the body), which do not describe the weakening of another drug’s effect due to interaction.