Where do Phase 1 reactions occur?
The enzymes involved in Phase I reactions are primarily located in the endoplasmic reticulum of the liver cell, they are called microsomal enzymes. Phase II metabolism involves the introduction of a hydrophilic endogenous species, such as glucuronic acid or sulfate, to the drug molecule.
What are the 2 phases of drug metabolism?
As discussed earlier, drug metabolism may be a detoxification pro- cess, or a bioactivation process, leading to varied consequences. The detoxification reactions can be divided into two broad cat- egories: Phase I (functionalization) and Phase II (conjugation) reactions .
What are the phases of drug metabolism?
Drugs can be metabolized by oxidation, reduction, hydrolysis, hydration, conjugation, condensation, or isomerization; whatever the process, the goal is to make the drug easier to excrete. The enzymes involved in metabolism are present in many tissues but generally are more concentrated in the liver.
Do all drugs go through Phase 1 and Phase 2 metabolism?
This is called conjugation and the product is called a conjugate. Metabolites formed in phase 2 are unlikely to be pharmacologically active. Some drugs undergo either phase 1 or phase 2 metabolism, but most undergo phase 1 metabolism followed by phase 2 metabolism.
What are the reactions under phase 1 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.
What is the difference between Phase 1 and Phase 2 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.
What causes slow drug metabolism?
Underlying health conditions can also influence your drug metabolic rate. Some conditions at greater risk of this are chronic liver disorders, kidney dysfunction, or advanced heart failure.
What are the factors affecting drug metabolism?
Further influencing factors are pregnancy, disease, or biological rhythms. Xenobiotics, drugs, constituents of herbal remedies, food constituents, ethanol, and tobacco can all influence enzyme expression or activity and, hence, affect drug metabolism.
What are the 3 phases of drug action?
Drug action usually occurs in three phases: Pharmaceutical phase. Pharmacokinetic phase. Pharmacodynamic phase.
What are the three phases of metabolism?
The metabolism of xenobiotics is often divided into three phases:- modification, conjugation, and excretion.
What is oxidation in phase 1 metabolism?
A common Phase I oxidation involves conversion of a C-H bond to a C-OH. This reaction sometimes converts a pharmacologically inactive compound (a prodrug) to a pharmacologically active one. By the same token, Phase I can turn a nontoxic molecule into a poisonous one (toxification).
Is demethylation a phase 1 metabolism?
The phase I metabolic transformations of dicentrine were found to be N-demethylation, N-oxidation, O-demethylation (9,10-OMe), O,O-demethylenation (1-OCH(2)O-2), and hydroxylation at the benzylic (C-4) and the aromatic (C-3) positions, whereas those for the phase II were O-glucuronidation and O-glucosylation of the …
What happens in Phase 1 of drug metabolism?
Phase I metabolism includes oxidization, decrease, hydrolysis and hydration reactions, every bit good as other rarer assorted reactions.
When do drugs go from Phase I to Phase II?
Once drugs have undergone Phase I metabolism, they become more polar and are easier to eliminate. Metabolites of many drugs undergo Phase II metabolism subsequent to phase I metabolism. Of course, some drugs undergo only Phase I or only Phase II metabolism.
Where are metabolites formed in a drug reaction?
Metabolites formed in man-made reactions are more polar and more readily excreted by the kidneys ( in piss ) and the liver ( in gall ) than those formed in nonsynthetic reactions. Some drugs undergo merely stage I or phase II reactions, therefore, phase Numberss reflect functional instead than consecutive categorization.
What happens in the first stage of metamorphosis?
Metamorphosis occurs in two stages, Phase I Metabolism, and Phase II Metabolism. Phase I Metabolism converts the drug into metabolite by formation of a new functional group or modifying it, while stage II Metabolism or reactions involve junction with autochthonal substance. Phase I Reactions Include: Oxidation, decrease,…