The blood–brain barrier is a preventive barrier that prevents MOST ____________ medications from reaching the brain

a. Lipid-soluble
b. Water-soluble
c. Non-ionized, unbound
d. Barbiturate

b
Rationale: a. Lipid-soluble medications readily pass the blood–brain barrier.
b. Water-soluble medications cannot permeate the blood–brain barrier.
c. A non-ionized, unbound medication can pass the blood–brain barrier.
d. A barbiturate is an example of a non-ionized, unbound drug.