Pharmacy PEBC Practice Exam

The liver is primarily responsible for drug metabolism due to its rich enzymatic activity and capacity to process various substances. Hepatic metabolism involves several biochemical processes, including oxidation, reduction, hydrolysis, and conjugation, which transform lipophilic compounds into more hydrophilic metabolites that can be easily excreted from the body.

The liver contains a vast array of cytochrome P450 enzymes that play a crucial role in the oxidative metabolism of many drugs. This organ enables the body to regulate the duration and intensity of drug action, and it also plays a key role in the detoxification of potentially harmful substances. Through first-pass metabolism, drugs administered orally may be significantly metabolized before reaching systemic circulation, which highlights the liver's pivotal role in pharmacokinetics.

While other organs like the kidneys are involved in drug excretion, and to some extent, extrahepatic metabolism can occur in tissues such as the lungs or intestines, none contribute to drug metabolism as extensively as the liver does. The heart's primary role is related to pumping blood and maintaining circulation rather than metabolizing substances. Thus, the liver stands out as the dominant organ for drug metabolism in the body.