Question

You are talking with a patient about taking tetracycline along with an antacid. You tell the patient not to take these two drugs at the same time because the antacid can reduce the absorption of tetracycline. When one drug reduces the effect of another drug, it is

A. an allergic reaction
B. a synergistic effect
C. an antagonistic effect
D. an adverse reaction

Answer 1

An antagonistic effect occurs when one drug reduces the effectiveness of another, such as when antacids decrease the absorption of tetracycline, hindering its therapeutic action. This interaction is different from synergistic effects where drugs enhance each other's efficacy.

Step-by-step explanation:

When one drug reduces the effect of another drug, this is known as an antagonistic effect. Taking tetracycline along with an antacid can lead to this type of interaction, where the antacid may decrease the absorption of tetracycline in the stomach, thereby reducing its efficacy. In contrast, a synergistic effect occurs when two drugs work together to produce a combined effect that is greater than the sum of their individual effects.

For instance, the combination of trimethoprim and sulfamethoxazole (Bactrim) exhibits a synergistic interaction that enhances their therapeutic effect. While antacids can have beneficial effects such as neutralizing stomach acid, they can also interact with other medications like tetracycline, which requires an acidic stomach environment for proper absorption. This interaction does not represent an allergic reaction, adverse reaction, or a synergistic effect.