What is Phase 1 and 2 of drug metabolism?
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.
Where does Phase 1 and 2 metabolism occur?
The majority of biotransformation takes place within the liver in cells called hepatocytes. However, several of the enzymes for phase I, phase II, and phase III reactions can also occur in extrahepatic tissues, such as adipose, intestine, kidney, lung, and skin.
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.
What is 2nd pass metabolism?
However, significant hepatic extraction still occurs because of second pass metabolism, whereby a fraction of venous blood travels through the hepatic portal vein and hepatocytes.
Where does phase 2 drug metabolism take place?
hepatocyte cytoplasm
Phase 2 metabolism involves conjugation – that is, the attachment of an ionised group to the drug. These groups can include glutathione, methyl or acetyl groups. These metabolic processes usually occur in the hepatocyte cytoplasm.
What occurs in Stage 2 of catabolism?
In stage II of catabolism, the metabolic pathway known as glycolysis. converts glucose into two molecules of pyruvate (a three-carbon compound with three carbon atoms) with the corresponding production of adenosine triphosphate (ATP).
What are the 4 main stages of metabolism?
ADVERTISEMENTS: Some of the main stages of cellular reaction in plants are as follows: (a) Glycolysis (b) Transition Reaction (c) The Krebs cycle (d) Electron Transport Chain.
What is first phase metabolism?
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. In other words, the metabolites are pharmacologically inactive.
Which of the following is Phase 2 metabolism reaction?
Phase II metabolic reactions are characterized as conjugation reactions and are catalyzed by enzymes known as transferases.
Do all drugs undergo phase 1 metabolism?
Some drugs undergo either phase 1 or phase 2 metabolism, but most undergo phase 1 metabolism followed by phase 2 metabolism. Aspirin (2-ethanoyloxybenzoic acid) hydrolyses to produce 2-hydroxybenzoic acid and ethanoic acid.
What is Phase 1 metabolism?
Not uncommonly, the term “phase I metabolism” contin- ues to be used, as an old-fashioned synon ym for P450-dependent oxidations. It i s simpler and much more accurate simply to say “P450” when that is what we mean. with a xenobiotic electrophil e. In most cases, hydrolysis and glutathion e conjugation are sequential. ) in a xenobiotic.
How does Phase 2 metabolism occur in a drug?
Hence, phase II metabolism occurs via methylation (methyltransferase), acetylation (N-acetyltransferase), sulfation (sulphotransferase) and glucuronidation (UDP-glucuronosyltransferase). The conjugated metabolites have increased molecular weight and become less active than the drug substrate.
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.