Drugs That Must Cross the Blood Brain Barrier and Enter

Drugs that must cross the blood brain barrier and enter the brain to exert therapeutic effects will be clinically useful if

A) they are lipophilic
B) they are hydrophilic but are able to enter the brain by active transport or facilitated diffusion
C) they are not subject to active transport enzymes (efflux pumps) that move the drug out of the brain and back into the systemic circulation
D) all the above
E) none of the above