The rate at which a drug reaches active sites in the brain is determined mostly by its degree of

A) water solubility.
B) lipid solubility.
C) drug metabolism via the liver.
D) depot binding in blood, bone, and fat.
E) drug metabolism in the kidneys.

Answer: B
Rationale: The rate at which a drug reaches active sites in the brain is determined mostly by its degree of lipid solubility.