Question:medium
A drug with high plasma protein binding property has which of the following properties?
A drug with high plasma protein binding property has which of the following properties?
Show Hint
Only free drug is filtered at the glomerulus.
Updated On: Jun 23, 2026
- Less GFR
- Less drug interaction
- Higher volume of distribution
- Less tubular secretion
Show Solution
The Correct Option is A
Solution and Explanation
Step 1: Think of the drug as existing in two pools, bound and free. The bound pool is too large to pass the glomerular filter, while the free pool moves with water and small solutes.
Step 2: When binding is high, the free pool shrinks. Since glomerular filtration only takes the free fraction, the filtered load falls, so glomerular filtration of the drug is reduced.
Step 3: By contrast, the proximal tubular secretion system uses active carriers that pull the drug from the protein, so this route is not limited by high binding.
Step 4: A highly bound drug is more prone to displacement interactions and stays largely in the vascular compartment, giving a small volume of distribution. Hence lesser GFR is the right answer.
\[\boxed{\text{Less GFR}}\]
Step 2: When binding is high, the free pool shrinks. Since glomerular filtration only takes the free fraction, the filtered load falls, so glomerular filtration of the drug is reduced.
Step 3: By contrast, the proximal tubular secretion system uses active carriers that pull the drug from the protein, so this route is not limited by high binding.
Step 4: A highly bound drug is more prone to displacement interactions and stays largely in the vascular compartment, giving a small volume of distribution. Hence lesser GFR is the right answer.
\[\boxed{\text{Less GFR}}\]
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