What occurs during phase 1 metabolism of a medication?

What occurs during phase 1 metabolism of a medication?

Phase I reactions of drug metabolism involve oxidation, reduction, or hydrolysis of the parent drug, resulting in its conversion to a more polar molecule. Phase II reactions involve conjugation by coupling the drug or its metabolites to another molecule, such as glucuronidation, acylation, sulfate, or glicine.

What is a Phase 1 metabolite?

Phase 1 metabolism involves chemical reactions such as oxidation (most common), reduction and hydrolysis. There are three possible results of phase 1 metabolism. The drug becomes completely inactive. One or more of the metabolites are pharmacologically active, but less so than the original drug.

What is a Phase 1 reaction?

Phase I reactions are broadly grouped into three categories: oxidation, reduction, and hydrolysis. As most small molecule drugs are lipophilic in nature, drug metabolism converts these hydrophobic compounds into more water soluble compounds that can be excreted. Typically, oxidation is the most common phase I reaction.

What are the 3 phases of metabolism?

The metabolism of xenobiotics is often divided into three phases:- modification, conjugation, and excretion.

What is the main purpose of Phase I metabolism?

Phase I metabolism consists of reduction, oxidation, or hydrolysis reactions. These reactions serve to convert lipophilic drugs into more polar molecules by adding or exposing a polar functional group such as -NH2 or -OH.

Where does Phase 1 and 2 metabolism occur?

The liver is the primary site for metabolism. Liver contains the necessary enzymes for metabolism of drugs and other xenobiotics. These enzymes induce two metabolism pathways: Phase I (functionalization reactions) and Phase II (biosynthetic reactions) metabolism.

What is phase II metabolism?

phase II reactions convert a parent drug to more polar (water soluble) inactive metabolites by conjugation of subgroups to -OH, -SH, -NH2 functional groups on drug. drugs metabolized via phase II reactions are renally excreted.

What is a Phase 2 reaction?

Phase II reactions consist of adding hydrophilic groups to the original molecule, a toxic intermediate or a nontoxic metabolite formed in phase I, that requires further transformation to increase its polarity. These reactions include conjugation reactions, glucuronidation, acetylation, and sulfation.

What are phase 1 enzymes?

Phase I enzymes are responsible for reactions involving oxidation, reduction, and hydrolysis. Oxidation involves the enzymatic addition of oxygen or removal of hydrogen, carried out by mixed function oxidases, often in the liver.

What are the 2 phases of metabolism?

Metabolism is often divided into two phases of biochemical reaction – phase 1 and phase 2. Some drugs may undergo just phase 1 or just phase 2 metabolism, but more often, the drug will undergo phase 1 and then phase 2 sequentially.

Does Lead undergo biotransformation?

Biotransformation-Lead (Pb) Environmental methylation of Pb involves methylcobalamin (Ridley et al., 1977). Lead in the metallic form when ingested is converted to a salt. Alkylleads can be metabolized by cytochrome P450 enzymes from tetra- to tri- to inorganic Pb (Kehoe and Thamann, 1931; Bolanowska, 1968).

What is the difference between Phase 1 and Phase 2 metabolism?

Phase II Metabolism •Phase I and Phase II Summary: Recall that Phase I reactions involve functionalization of drugs through oxidation, reduction, and hydrolysis reactions. Once drugs have undergone Phase I metabolism, they become more polar and are easier to eliminate.

What are the phases of metabolism in pharmacology?

Overview Phase I metabolism oxidation (via cytochrome P450), reduction, and hydrolysis reactions Phase II metabolism glucuronidation, acetylation, and sulfation reactions “conjugation reactions” that increase water solubility of drug with a polar moiety glucuronate, acetate, and sulfate, respectively

What are the Phase 1 and Phase 2 reactions of biotransforming enzymes?

Reactions catalyzed by xenobiotic biotransforming enzymes are generally divided into two groups: Phase I and phase II. 1. Phase I reactions involve hydrolysis, reduction and oxidation, exposing or introducing a functional group (-OH, -NH 2, -SH or –COOH) to increase reactivity and slightly increase hydrophilicity. 1 H 2.

What is the difference between Phase I and Phase II reactions?

Another difference is that Phase II reactions are detoxification reactions, meaning that the resulting metabolites do not have any toxic side effects. Remember, this was not always the case in Phase I reactions, as sometimes Phase I reactions yield metabolites that may be pharmacologically inactive but are nevertheless toxic to the body.

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