[usluipek]

Pls, Can someone explain why only free non-ionized drug contribute to drug concentration gradient?

 

[usluipek]

Thanks for the explanation. But if an ionized drug does not cross membrane, it will accumulate outside of cell and will increase extracelluar concentration. I am still a little confused.

 

[usluipek]

By the way, where are you reading this is not high yield for the USMLE

I was going over concepts, and came across this question. May be USMLE will not ask this directly, but I think concept is important, especially for the first reading.