Pharmacokinetics Question

[Focused1]

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You are investigating two new drugs, A and B. During the course of animal studies, you find that following intravenous administration, drug A is 90% bound to albumin. Drug B is found to be 50% bound to albumin. With respect to pharmacokinetics, which of the following is a correct statement based on the given information?

• A Compared to drug B, more drug A is filtered by the glomerulus
• B 90% of drug A is available for distribution into tissues
• C 90% of drug A is pharmacologically active
• D Drug A is more dependent on liver biotransformation for clearance than drug B
• E Drug A is 40% more active than drug B

 

[aspiringmd1015]

def not A, C, or E. either B or D. Thinking about lipid solubility here, if its lipid soluble mus tbe carried by albumin, so if its lipid soluble, it needs biotransformation to be cleared, so im leaning on D, but B makes sense too.

 

[Focused1]

The key says D.. but i dont understand it..

 

[LichenPlanus]

Drug A = 90% bound to albumin -> more retained in plasma bound to albumin -> less Vd (less distributed to tissue)/more retained in plasma -> more metabolized by liver
Drug B = 50% bound to albumin -> less bound to protein/albumin = higher Vd (volume distribution) -> more distributed to tissue directly - less liver metabolism