Difference Between Phase I and Phase II 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.

1. Where does Phase 1 and 2 metabolism occur?
2. What is phase II metabolism?
3. What is first phase metabolism?
4. What are the three phases of metabolism?
5. Is first pass metabolism the same as Phase 1?
6. What is Glucuronidation metabolism?
7. Where does Phase 2 of drug metabolism occur?
8. How many phases of metabolism are there?
9. What are the two parts of metabolism?
10. What is oxidation in metabolism?
11. What affects drug metabolism?
12. Does a fast metabolism affect medication?

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 is phase II metabolism?

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 .

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.

What are the three phases of metabolism?

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

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 is Glucuronidation metabolism?

n. a metabolic process by which drugs or other substances are combined with glucuronic acid to form more water-soluble compounds, which are more readily excreted by the kidneys or in bile. Glucuronidation is the most prevalent of the Phase II reactions of drug metabolism.

Where does Phase 2 of drug metabolism 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.

How many phases of metabolism are there?

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 two parts of metabolism?

There are two categories of metabolism: catabolism and anabolism. Catabolism is the breakdown of organic matter, and anabolism uses energy to construct components of cells, such as proteins and nucleic acids.

What is oxidation in metabolism?

Listen to pronunciation. (OK-sih-DAY-tiv meh-TA-buh-lih-zum) A chemical process in which oxygen is used to make energy from carbohydrates (sugars). Also called aerobic metabolism, aerobic respiration, and cell respiration.

What affects drug metabolism?

Individual drug metabolism rates are influenced by genetic factors, coexisting disorders (particularly chronic liver disorders and advanced heart failure), and drug interactions (especially those involving induction or inhibition of metabolism). For many drugs, metabolism occurs in 2 phases.

Does a fast metabolism affect medication?

If your body metabolizes a drug too quickly, you may not get any benefit from the prescribed dose. Your dose may need to be increased to reach a therapeutic effect. If your body metabolizes a drug too slowly, it stays active longer, and may be associated with side effects.