Question

What is the process whereby a drug is transformed by the liver to another chemical?

Answer 1

The liver performs drug metabolism, a biotransformation process that involves two phases: Phase I (oxidation, reduction, hydrolysis) and Phase II (conjugation). In the liver, enzymes convert drugs into less harmful metabolites for excretion, though sometimes this leads to toxication.

Step-by-step explanation:

Drug Metabolism in the Liver

The process whereby a drug is transformed by the liver into another chemical is known as drug metabolism. This vital function of the liver is part of the body's detoxification mechanism, which converts toxic substances into less harmful products and then into forms that are easily excreted. The liver participates in up to 500 functions, many in combination with other systems, but one of its primary roles is the breakdown or modification of toxic substances, including alcohol, medication, and physiological substances, such as hormones.

Drug metabolism generally occurs in two phases in the liver. Phase I involves oxidation, reduction, and hydrolysis. An example is the oxidation of alcohols to their corresponding acids. Phase II is characterized by conjugation, wherein substances are coupled with other compounds to facilitate excretion. This metabolism is facilitated by enzymes like Catechol-O-Methyl-Transferase (COMT) and Mono-Amine Oxidase (MAO), transforming substances into excretable metabolites like Vanillylmandelic acid (VMA), the major excretory product of catecholamines.

The liver's ability to modify substances can sometimes lead to toxication, where the metabolite produced is more toxic than its precursor. Nonetheless, the overall detoxification mechanism is crucial in maintaining homeostasis within the body.

Answer 2

The liver transforms a drug into another chemical through drug metabolism, involving phases of oxidation, reduction, and conjugation. This detoxification results in substances that can be excreted from the body, and is a part of the liver's many functions. The FDA ensures the safety and effectiveness of drugs prior to approval.

Step-by-step explanation:

The Liver and Drug Metabolism

The process whereby a drug is transformed by the liver into another chemical is known as drug metabolism.

This vital process involves a detoxification mechanism where the liver functions to convert toxic substances into less harmful products. Generally, drug metabolism can be divided into two phases:

Phase I includes oxidation, reduction, and hydrolysis while Phase II involves conjugation.

For example, in the case of alcohol such as ethanol, it is oxidized to acetaldehyde by the enzyme alcohol dehydrogenase in a reaction known as a zeroth-order reaction, especially at high concentrations of ethanol.

The liver's ability to metabolize substances is crucial for the detoxification of various harmful foreign substances, such as drugs, as well as physiological substances like hormones that must be regularly eliminated.

This comprehensive process ensures these substances become suitable for excretion.

Notably, the liver is estimated to perform up to 500 different functions, often in collaboration with other systems and organs, with drug metabolism being just one of these critical roles.

The extensive process of drug approval by the Food and Drug Administration (FDA) starts after a drug's initial discovery and development, ensuring that the drug is not toxic and is effective for intended treatments.