Quick Answer: What Are The Phases Of Biotransformation?

Which body organ is the major site of drug metabolism?

liverAlthough many sites of metabolism and excretion exist, the chief organ of metabolism is the liver, while the organ primarily tasked with excretion is the kidney.

Any significant dysfunction in either organ can result in accumulation of the drug or its metabolites in toxic concentrations..

What is biotransformation phase1?

Phase I biotransformation reactions introduce or expose functional groups on the drug with the goal of increasing the polarity of the compound. … Typically, oxidation is the most common phase I reaction. The hepatic cytochrome P450 system is the most important of the phase I oxidation systems (Figure 1).

What is a Phase 2 reaction?

Phase II Reactions. … Phase II reactions are conjugation reactions where a molecule normally present in the body is added to the reactive site of the Phase I metabolite . The result is a conjugated metabolite that is more water soluble than the original xenobiotic or Phase I metabolite .

Is hydrolysis oxidation or reduction?

Hydrolysis is the chemical breakdown of substances by water and depends on the chemistry, solubility, pH, and the oxidation–reduction (Eh or redox) potential of compound.

What is cytochrome p450?

Cytochrome P450 enzymes play a role in the synthesis of many molecules including steroid hormones, certain fats (cholesterol and other fatty acids), and acids used to digest fats (bile acids).

What does bioavailability mean?

Definition/Introduction. Bioavailability refers to the extent a substance or drug becomes completely available to its intended biological destination(s).

How many phases are there in biotransformation?

two stagesBiotransformation involves two stages: phase I mainly involving P-450 (CYP) family and phase II catalyzed by conjugation enzymes like glutathione S-transferase (GST), UDP-glucuronosyltransferase (UGT), and N-acetyltransferase (NAT).

What is the process of biotransformation?

Biotransformation is the process by which a substance changes from one chemical to another (transformed) by a chemical reaction within the body. Metabolism or metabolic transformations are terms frequently used for the biotransformation process.

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. … One or more of the metabolites are pharmacologically active, but less so than the original drug.

Why are drugs conjugated in Phase 2 metabolism?

Conjugation. Glucuronidation, the most common phase II reaction, is the only one that occurs in the liver microsomal enzyme system. Glucuronides are secreted in bile and eliminated in urine. Thus, conjugation makes most drugs more soluble and easily excreted by the kidneys.

What is the meaning of xenobiotics?

Xenobiotics have been defined as chemicals to which an organism is exposed that are extrinsic to the normal metabolism of that organism. Without metabolism, many xenobiotics would reach toxic concentrations. Most metabolic activity inside the cell requires energy, cofactors, and enzymes in order to occur.

What is another term for biotransformation of a drug?

What is another term for biotransformation of a drug? Metabolism.

What are the 3 phases of drug action?

Drug action usually occurs in three phases: Pharmaceutical phase. Pharmacokinetic phase. Pharmacodynamic phase.

What is the difference between biotransformation and metabolism?

In short, “metabolism of drugs” is a form of biotransformation which happens to drugs in a body, whereas “biotransformation” is a more general term which applies equally well to the actions of a disembodied enzyme digesting an oil slick.

What is biotransformation and where in the body does it occur?

Primary Biotransformation Site: The Liver Microsomal enzymes are associated with most Phase I reactions. … Cytosolic enzymes are non-membrane-bound and occur free within the cytoplasm . They are generally associated with Phase II reactions, although some oxidation and reduction enzymes are contained in the cytosol .

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 are the phases of drug metabolism?

The metabolism of xenobiotics is often divided into three phases:- modification, conjugation, and excretion. These reactions act in concert to detoxify xenobiotics and remove them from cells.

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.