This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pharmacokinetics, Subject name: Pharmacology
High plasma protein binding of a drug results in:- 
Select and explain. 
A. Decreased glomerular filtration, B. High volume of distribution, C. Lowers duration of action, D. Less drug interaction
A: Decreased glomerular filtration
Answer: A: Decreased glomerular filtration 
Explanation: * High plasma protein binding (PPB) of a drug decreases its distribution into tissue and thus lower the volume of distribution. * As only free drug can be metabolized or excreted, high PPB usually increases the duration of action. * With higher PPB, there is more chance of getting displaced by other drugs leading to more drug interactions. * Drugs with high plasma protein binding have lesser glomerular filteration as proteins cannot be filtered across the glomerulus.