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.
What is the difference between Phase 1 and Phase 2 metabolism?
Phase I: Yields a polar, water-soluble, metabolite that is often still active. Many of the products in this phase can also become substrates for phase II. Phase II: Yields a large polar metabolite by adding endogenous hydrophilic groups to form water-soluble inactive compounds that can be excreted by the body.
Do all drugs undergo Phase 1 and Phase 2 metabolism?
Some drugs undergo either phase 1 or phase 2 metabolism, but most undergo phase 1 metabolism followed by phase 2 metabolism.
What is drug metabolism Slideshare?
3 Introduction • Biotransformation: Chemical alteration of the drug in body that converts nonpolar or lipid soluble compounds to polar or lipid insoluble compounds • Consequences of biotransformation • Active drug Inactive metabolite : Pentobarbitone, Morphine, Chloramphenicol • Active drug Active metabolite: …
What is a Phase 2 reaction?
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 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.
Which enzymes are involved in phase 1 metabolism?
Cytochrome P450 enzymes (CYPs or P450s) are the most important enzymes involved in the phase I metabolism of drugs and poisons in humans, while UDP glycosyltransferases catalyze the majority of phase II 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.
What is the importance of drug metabolism?
The purpose of metabolism in the body is usually to change the chemical structure of the substance, to increase the ease with which it can be excreted from the body. Drugs are metabolized through various reactions including: Oxidation. Reduction.
Which is phase 2 drug metabolizing reaction?
Abstract. Background: Phase II biotransformation reactions (also ‘conjugation reactions’) generally serve as a detoxifying step in drug metabolism. Phase II drug metabolising enzymes are mainly transferases.
What is phase 2 enzymes?
Phase 2 enzymes traditionally refer to the enzymes catalyzing the conjugation reactions, such as glutathione S-transferase (GST), UDP-glucuronosyltransferase (UGT), N-acetyltransferase (NAT), and sulfotransferase (SULT).
What is a Phase 2 enzyme?
What is the main purpose of Phase I metabolism?
Phase I biotransformation reactions introduce or expose functional groups on the drug with the goal of increasing the polarity of the compound.
What is Phase II reaction?
Phase II reactions are also known as conjugation reactions. Conjugation. To join together, as in a xenobiotic molecule binding with a sugar or glutathione molecule.
What factors affect drug metabolism?
Physiological factors that can influence drug metabolism include age, individual variation (e.g., pharmacogenetics), enterohepatic circulation, nutrition, intestinal flora, or sex differences. In general, drugs are metabolized more slowly in fetal, neonatal and elderly humans and animals than in adults.
Where does phase 2 drug metabolism take place?
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. The attachment of an ionised group makes the metabolite more more water soluble.