Drug metabolism

metabolismxenobiotic metabolismmetabolic stabilitymetabolizedphase II metabolismconjugationphase I metabolismconjugatedphase Imetabolised
Drug metabolism is the metabolic breakdown of drugs by living organisms, usually through specialized enzymatic systems.wikipedia
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Xenobiotic

xenobioticsxenogenicxeno
More generally, xenobiotic metabolism (from the Greek xenos "stranger" and biotic "related to living beings") is the set of metabolic pathways that modify the chemical structure of xenobiotics, which are compounds foreign to an organism's normal biochemistry, such as any drug or poison.
The body removes xenobiotics by xenobiotic metabolism.

Efflux (microbiology)

effluxefflux pumpefflux pumps
Finally, in phase III, the conjugated xenobiotics may be further processed, before being recognised by efflux transporters and pumped out of cells.
Efflux pumps are capable of moving a variety of different toxic compounds out of cells, such as antibiotics, heavy metals, organic pollutants, plant-produced compounds, quorum sensing signals, bacterial metabolites and neurotransmitters via active efflux, which is vital part for xenobiotic metabolism.

Drug interaction

interactdrug interactionsdrug-drug interaction
Drug metabolism also affects multidrug resistance in infectious diseases and in chemotherapy for cancer, and the actions of some drugs as substrates or inhibitors of enzymes involved in xenobiotic metabolism are a common reason for hazardous drug interactions.
Many drug interactions are due to alterations in drug metabolism.

Prodrug

pro-drugprodrugsinactive prodrug
This reaction sometimes converts a pharmacologically inactive compound (a prodrug) to a pharmacologically active one.
A prodrug is a medication or compound that, after administration, is metabolized (i.e., converted within the body) into a pharmacologically active drug.

Detoxification

detoxdetoxifydetoxifying
These reactions often act to detoxify poisonous compounds (although in some cases the intermediates in xenobiotic metabolism can themselves cause toxic effects).
An animal's metabolism can produce harmful substances which it can then make less toxic through reduction, oxidation (collectively known as redox reactions), conjugation and excretion of molecules from cells or tissues.

Enzyme

enzymologyenzymesenzymatic
Drug metabolism is the metabolic breakdown of drugs by living organisms, usually through specialized enzymatic systems.
Another example comes from enzymes in the liver called cytochrome P450 oxidases, which are important in drug metabolism.

Toxication

toxificationprotoxintoxicated
By the same token, Phase I can turn a nontoxic molecule into a poisonous one (toxification).
Phase I of drug metabolism are bioactivation pathways, which are catalyzed by CYP450 enzymes, produce toxic metabolites and thus have the potential to damage cells.

Pharmacology

pharmacologistpharmacologicalpharmacologically
The metabolism of pharmaceutical drugs is an important aspect of pharmacology and medicine.
Drug metabolism is assessed in pharmacokinetics and is important in drug research and prescribing.

Paracetamol

acetaminophenPanadolTylenol PM
The classes of pharmaceutical drugs that utilize this method for their metabolism include phenothiazines, paracetamol, and steroids.

Glucuronidation

glucuronidatedglucuronideglucuronidized
Glucuronidation is often involved in drug metabolism of substances such as drugs, pollutants, bilirubin, androgens, estrogens, mineralocorticoids, glucocorticoids, fatty acid derivatives, retinoids, and bile acids.

Biotransformation

conjugateconjugationconjugated
These pathways are a form of biotransformation present in all major groups of organisms, and are considered to be of ancient origin. In subsequent phase II reactions, these activated xenobiotic metabolites are conjugated with charged species such as glutathione (GSH), sulfate, glycine, or glucuronic acid.

N-acetyltransferase

N''-acetyltransferaseacetyltransferaseN
Acetyl groups are important in the conjugation of metabolites from the liver, to allow excretion of the byproducts (phase II metabolism).

Glucuronosyltransferase

UDP-glucuronosyltransferaseUDP-glucuronyltransferaseglucuronyl transferase
Glucuronosyltransferases are responsible for the process of glucuronidation, a major part of phase II metabolism.

Multiple drug resistance

multidrug resistancemultidrug-resistantmulti-drug resistant
Drug metabolism also affects multidrug resistance in infectious diseases and in chemotherapy for cancer, and the actions of some drugs as substrates or inhibitors of enzymes involved in xenobiotic metabolism are a common reason for hazardous drug interactions.

Trimebutine

As an example, the major metabolite of the pharmaceutical trimebutine, desmethyltrimebutine (nor-trimebutine), can be efficiently produced by in vitro oxidation of the commercially available drug.
The major product from drug metabolism of trimebutine in human beings is nortrimebutine, which comes from removal of one of the methyl groups attached to the nitrogen atom.

Glutathione

glutathione metabolismglutathionylGSH
In subsequent phase II reactions, these activated xenobiotic metabolites are conjugated with charged species such as glutathione (GSH), sulfate, glycine, or glucuronic acid.
Glutathione facilitates metabolism of xenobiotics.

Glyoxalase system

glyoxalaseglyoxylase pathway
Examples of these specific detoxification systems are the glyoxalase system, which removes the reactive aldehyde methylglyoxal, and the various antioxidant systems that eliminate reactive oxygen species.
Firstly, in contrast to the amazing substrate range of many of the enzymes involved in xenobiotic metabolism, it shows a narrow substrate specificity.

Acetylcysteine

N-acetylcysteineN''-acetylcysteineN-acetyl cysteine
A common example is the processing of glutathione conjugates to acetylcysteine (mercapturic acid) conjugates.
It is normally conjugated by glutathione, but when taken in excess, the body's glutathione reserves are not sufficient to deactivate the toxic NAPQI.

Glucuronic acid

glucuronateD-glucuronate D -glucuronic acid
In subsequent phase II reactions, these activated xenobiotic metabolites are conjugated with charged species such as glutathione (GSH), sulfate, glycine, or glucuronic acid.
UDP-α- D -glucuronic acid (UDPGA) is often involved in the phase II metabolism (conjugation) of lipophilic xeno- and endobiotics.

Sulfation

sulfatedsulfate conjugationnonsulfated
It is among the reactions in phase II drug metabolism, frequently effective in rendering a xenobiotic less active from a pharmacological and toxicological standpoint, but sometimes playing a role in the activation of xenobiotics (e.g. aromatic amines, methyl-substituted polycyclic aromatic hydrocarbons).

First pass effect

first-pass metabolismfirst-pass effectfirst pass metabolism
If a drug is taken into the GI tract, where it enters hepatic circulation through the portal vein, it becomes well-metabolized and is said to show the first pass effect.
The first pass effect (also known as first-pass metabolism or presystemic metabolism) is a phenomenon of drug metabolism whereby the concentration of a drug is greatly reduced before it reaches the systemic circulation.

Flavin-containing monooxygenase

dimethylaniline monooxygenase (N-oxide-forming)FAD monooxygenaseFlavin-containing monooxygenase system
Drug metabolism is one of the most important factors to consider when developing new drugs for therapeutic applications.

Enzyme induction and inhibition

inductioninducersinduce
In general, anything that increases the rate of metabolism (e.g., enzyme induction) of a pharmacologically active metabolite will decrease the duration and intensity of the drug action.
These terms are of particular interest to pharmacology, and more specifically to drug metabolism and drug interactions.

Cytochrome P450

cytochrome P450 oxidaseP450CYP450
In phase I, enzymes such as cytochrome P450 oxidases introduce reactive or polar groups into xenobiotics.
CYPs are the major enzymes involved in drug metabolism, accounting for about 75% of the total metabolism.

Butyrate—CoA ligase

butyrate-CoA ligaseXM-ligase
This enzyme participates in the glycine conjugation of xenobiotics and butanoate metabolism.