Certified Addiction Counselor (CAC) Practice

Which type of drug interaction produces effects that are less than the sum of the drugs involved?

1. Synergistic interaction

2. Additive interaction

3. Antagonistic interaction

4. Potentiation

The correct answer is: Antagonistic interaction

The correct answer focuses on antagonistic interactions, which are characterized by one drug reducing or inhibiting the effects of another. In these interactions, the combined effect of the drugs is indeed less than what would be expected if their effects were simply added together. This is important in clinical practice as it highlights the need for awareness of potential interactions between medications, especially for patients receiving multiple prescriptions. For example, if a patient is using a stimulant and an anti-anxiety medication together, the sedative effects of the latter might counteract the stimulating effects of the former, resulting in an overall diminished effect compared to taking either one of those drugs alone. Recognizing antagonistic interactions can be crucial for effective treatment planning and ensuring patient safety. In contrast, synergistic interactions occur when the combined effect of two drugs is greater than the sum of their individual effects, while additive interactions lead to effects that equal the total of each drug's effects. Potentiation refers to a situation where one drug enhances the effect of another, leading to an increased overall effect. Understanding these types of interactions is essential for safe medication administration and for predicting patient responses to drug combinations.