What form of an acidic drug favors partitioning across a cell membrane (lipid bilayer)?

Question

Quizplus · Accepted Answer

A lipid bilayer is composed of hydrophobic fatty acid chains, making it a non-polar environment. Therefore, the most favorable form of a drug to partition across a cell membrane is the non-ionized or unionized form (HA), as it is able to interact with the non-polar environment. The ionized form (A-) is polar and less likely to permeate the membrane. NaA is an ionized form and not favored for the same reason.

What Form of an Acidic Drug Favors Partitioning Across a Cell