What is metabolism in pharmacokinetics?

Metabolism describes the chemical reactions that change drugs into compounds which are easier to eliminate. The products of these chemical reactions are called metabolites. … Producing metabolites which consist of polar molecules means that they can be excreted in body fluids such as urine and bile.

What is metabolism in pharmacology?

Drug metabolism is the term used to describe the biotransformation of pharmaceutical substances in the body so that they can be eliminated more easily. … 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.

What is the purpose 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.

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What are the 2 phases of 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 4 steps of pharmacokinetics?

Pharmacokinetics is the aspect of pharmacology dealing with how drugs reach their site of actionand are removed from the body. The following processes govern the rate of accumulation and removal of drug from an organism–absorption, distribution, metabolism, and excretion.

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.

What is metabolism activity?

Metabolism is a balancing act involving two kinds of activities that go on at the same time: building up body tissues and energy stores (called anabolism) breaking down body tissues and energy stores to get more fuel for body functions (called catabolism)

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 factors that affect drug metabolism?

Many factors affect the rate and pathway of metabolism of drugs, and the major influences can be sub-divided into internal (physiological and pathological) and external (exogenous) factors as indicated below: Internal: species, genetic (strain), sex, age, hormones, pregnancy, disease. External: diet, environment.

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What organs are involved in drug metabolism?

Most drugs must pass through the liver, which is the primary site for drug metabolism. Once in the liver, enzymes convert prodrugs to active metabolites or convert active drugs to inactive forms.

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.

Where does Phase 1 and 2 metabolism occur?

The majority of biotransformation takes place within the liver in cells called hepatocytes. However, several of the enzymes for phase I, phase II, and phase III reactions can also occur in extrahepatic tissues, such as adipose, intestine, kidney, lung, and skin.

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.

What are the 3 phases of drug action?

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

What is a half life and how do you calculate a drug’s half life?

In brief :

  1. Half-life (t½) is the time required to reduce the concentration of a drug by half.
  2. The formula for half-life is (t½ = 0.693 × Vd /CL)
  3. Volume of distribution (Vd) and clearance (CL) are required to calculate this variable.
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What are the principles of pharmacodynamics?

Pharmacodynamic mechanisms regulate the effects of drugs on the human body. As noted earlier, drug-receptor binding results in multiple, complex chemical interactions. The site on the receptor at which a drug binds is called its binding site.

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