FPGEE for National Association of Boards of Pharmacy (NABP) Practice Exam

Ester drugs are primarily hydrolyzed where in the body?

1. In the liver

2. In the plasma

3. In the intestines

4. In the kidneys

The correct answer is: In the plasma

Ester drugs are primarily hydrolyzed in the plasma due to the action of plasma esterases. These enzymes, which are predominantly found in the blood, catalyze the hydrolysis of ester bonds, leading to the breakdown of ester compounds into their respective acids and alcohols. This process allows for the rapid inactivation and clearance of ester drugs, making plasma the primary site of hydrolysis. This mechanism is crucial in pharmacology as it affects the pharmacokinetics of ester-based medications, influencing their duration of action and overall therapeutic effect. Although other organs, such as the liver and intestines, are involved in drug metabolism, the hydrolysis of ester drugs primarily occurs in the plasma due to the specific presence of the necessary enzymes in that compartment.