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 is the difference between Phase 1 and Phase 2 reactions?

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 I and II metabolism?

The key difference between phase I and phase II metabolism is that the phase I metabolism converts a parent drug to polar active metabolites while phase II metabolism converts a parent drug to polar inactive metabolites. Metabolism (drug metabolism) is the anabolic and catabolic breakdown of drugs by living organisms.

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. In other words, the metabolites are pharmacologically inactive.

Which of the following is an example of phase 1 reaction?

Phase I reactions include introducing or removing of –OH, -COOH, -NH2 and –SH. This phase I reactions are also known as functionalization reactions.

Is first pass metabolism the same as Phase 1?

Phase 1 reactions are often oxidations or hydrolysis reactions, although reductions also occur. In terms of first-pass metabolism in the liver – hydrolysis of pharmacologically inactive esters (prodrugs) to active drugs are important phase 1 reactions.

What are the three phases of metabolism?

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

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 2 phases of drug 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 are the 2 phases in the process of metabolism?

Two phases of metabolism are anabolism and catabolism. The sum of the physical and chemical processes by which living organized substance is built up and maintained (anabolism).

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.

Is hydroxylation a Phase 1 reaction?

Hydroxylation is the most common reaction type in phase I metabolism and usually produces a chemically stable and more polar hydroxylated metabolite than the drug.

Which steps involved in 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.

Where do Phase 2 reactions occur?

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.

Where are cyp450 enzymes found?

Cytochrome P450 enzymes are primarily found in liver cells but are also located in cells throughout the body. While a large body of knowledge exists on the role of CYP450s in xenobiotic metabolism, recent studies have begun to reveal the endogenous functions carried out by this important superfamily of enzymes.

Which of the following is NOT Phase 1 metabolic reaction?

Phase 1 reactions are also known as a synthetic reaction. The phase I reactions are detoxification pathways.

Q. Which of the following reactions is not a Phase I metabolic transformation?
B. Conjugation to alcohols
C. Monoamine oxidases
D. Esterhydrolysis

Which of the following statement is the closest description of phase 1 metabolism?

Which of the following statements is the closest description of Phase I metabolism? a) Reactions which add a polar molecule to a functional group already present on a drug or one of its metabolites.

What is oxidation in phase 1 metabolism?

Phase 1 metabolism can involve reduction or hydrolysis of the drug, but the most common biochemical process that occurs is oxidation. (Oxidation is the chemical reaction that occurs when apples turn brown when exposed to the oxygen in air).

What phase of biotransformation is hydrolysis?


Classification Enzymes
Hydrolysis Epoxide hydrolase
Phase II
Conjugation UDP-GT

What is a hydrolysis reaction?

Thus, a hydrolysis reaction is the cleavage of chemical bonds by the addition of water or a base that supplies the hydroxyl ion ( OH). A chemical bond is cleaved, and two new bonds are formed, each one having either the hydrogen component (H) or the hydroxyl component (OH) of the water molecule.

What is hydrolysis in metabolism?

Usually hydrolysis is a chemical process in which a molecule of water is added to a substance. Sometimes this addition causes both the substance and water molecule to split into two parts. In such reactions, one fragment of the target molecule (or parent molecule) gains a hydrogen ion.

What is a conjugation reaction?

Conjugation reactions usually involve metabolite activation by a high–energy intermediate and have been classified into two general types: type I (e.g., glucuronidation and sulfonation), in which an activated conjugating agent combines with substrate to yield the conjugated product, and type II (e.g., amino acid …

What are the process of conjugation?

Conjugation is the process by which one bacterium transfers genetic material to another through direct contact. During conjugation, one bacterium serves as the donor of the genetic material, and the other serves as the recipient. The donor bacterium carries a DNA sequence called the fertility factor, or F-factor.

What drugs are metabolites?

A drug metabolite is a byproduct of the body breaking down, or “metabolizing,” a drug into a different substance. The process of metabolizing a drug is predictable and certain; everyone metabolizes drugs the same way.

What does a glucuronide do?

Glucuronidation is a major mechanism for the formation of water-soluble substrates from xenobiotics, leading to their elimination from the body in bile or urine.

What enzyme do cats lack?

Cats lack the major phenol UDP-glucuronosyltransferase (UGT) enzymes, including UGT1A6 and UGT1A9, that glucuronidate acetaminophen and propofol.

How can I increase my glucuronidation?

Supporting Glucuronidation:

  1. Citrus Fruits: limonene from the peels of oranges, lemons, limes, and grapefruit and believed to induce UGT activity.
  2. Cruciferous vegetables.
  3. Dandelion, rooibos, honeybush, and rosemary tea.
  4. Astaxanthin found in algae, yeast, trout, krill, shrimp, and crayfish.