Question

Which one of the following is a pharmacodynamic drug interaction?

• A. Inhibition of drug metabolism
• B. Increase in drug elimination
• C. Additive or synergistic effects
• D. Change in the pH of the GIT

Hint:

Pharmacodynamic = What the drugs "Do" to each other at the receptor.

Answer 1

The Correct Option is C

Step 1: Concept
Drug interactions are classified as pharmacokinetic (how the body acts on the drug) or pharmacodynamic (how the drug acts on the body).

Step 2: Meaning
Pharmacodynamic interactions occur when drugs act on the same receptor or physiological system to enhance or oppose each other.

Step 3: Analysis
Metabolism, elimination, and pH changes are all pharmacokinetic processes (ADME). Additive effects (1+1=2) or synergistic effects (1+1=3) occur when two drugs work together at the site of action.

Step 4: Conclusion
Therefore, additive or synergistic effects represent a pharmacodynamic drug interaction.

Final Answer: (C)