What are the phases of drug metabolism?

Drug metabolism reactions comprise of two phases: Phase I (functionalization) reactions such as oxidation, hydrolysis; and Phase II (conjugation) reactions such as glucuronidation, sulphate conjugation. Oxidation reactions are the most common and vital.

What are the phases of metabolism?

Metabolism is often divided into two phases: Phase 1 metabolism involves chemical reactions such as oxidation (most common), reduction and hydrolysis. There are three possible results of phase 1 metabolism.

How many phases are there in drug metabolism?

Drug metabolism is divided into three phases.

What are the four stages of drug metabolization?

The four stages are absorption, distribution, metabolism, 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 two phases of drug metabolism?

Drug metabolism reactions comprise of two phases: Phase I (functionalization) reactions such as oxidation, hydrolysis; and Phase II (conjugation) reactions such as glucuronidation, sulphate conjugation. Oxidation reactions are the most common and vital.

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What is Phase 2 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 causes slow drug metabolism?

Underlying health conditions can also influence your drug metabolic rate. Some concerning ones are chronic liver disorders, kidney dysfunction, or advanced heart failure. Drug and Food Interactions. CYP450 enzymes can be impacted by the foods you eat and other drugs you take.

What is oxidation in drug metabolism?

In most cases, an oxygen atom is retained in the metabolite, although some reactions, such as dealkylation, result in loss of the oxygen atom in a small fragment of the original molecule. Oxidation reactions are catalysed by a diverse group of enzymes, of which the cytochrome P450 system is the most important.

What is first pass metabolism of drug?

The first-pass metabolism or the first-pass effect or presystemic metabolism is the phenomenon which occurs whenever the drug is administered orally, enters the liver, and suffers extensive biotransformation to such an extent that the bioavailability is drastically reduced, thus showing subtherapeutic action (Chordiya …

What are the 5 ways drugs can enter your body?

For example, there are five methods of drug abuse which allow drugs to enter the body: swallowing, smoking, snorting, through suppositories and injecting.

How do drugs break down in the body?

Nucleoside analog drugs are not broken down by the liver but travel through the kidneys where the liver sometimes combines them with other chemicals so they can be dissolved and passed out in the urine. The cytochrome p450 system, a group of enzymes, breaks down drugs before they are metabolized by the liver.

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How do drugs exit the body?

While drugs and their metabolites are mostly excreted by the kidneys into urine, drugs can also leave the body in other methods, such as breath and sweat, hence the noticeable smell of alcohol on someone who has been drinking very heavily.

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.

Where does phase 1 metabolism occur?

Although Phase I drug metabolism occurs in most tissues, the primary and first pass site of metabolism occurs during hepatic circulation. Additional metabolism occurs in gastrointestinal epithelial, renal, skin, and lung tissues.

What are the two routes by which drugs can be eliminated into the system?

It is accomplished in two ways, either by excretion of an unmetabolized drug in its intact form or by metabolic biotransformation followed by excretion. While excretion is primarily carried out by the kidneys, other organ systems are involved as well.

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