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Phase 1 And Phase 2 Reactions In Drug Metabolism Pdf

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Commonly there are four types of reactions involved in drug metabolism. These are: oxidation reduction hydrolysis conjugation The first three are often lumped together as phase I reactions, while the fourth process, conjugation, is called phase II metabolism. A common scheme in the overall metabolism of drugs is that metabolites are metabolized. In particular a drug may be oxidized, reduced or hydrolyzed and then another group may be added in a conjugation step.

Chemical Reactions

The liver is the principal site of drug metabolism for review, see [ 1 ]. Although metabolism typically inactivates drugs, some drug metabolites are pharmacologically active—sometimes even more so than the parent compound. An inactive or weakly active substance that has an active metabolite is called a prodrug, especially if designed to deliver the active moiety more effectively. 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. Drug metabolism rates vary among patients.

If your institution subscribes to this resource, and you don't have a MyAccess Profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus. Please consult the latest official manual style if you have any questions regarding the format accuracy. All organisms are exposed to foreign chemical compounds xenobiotics in the air, water, and food. To ensure elimination of pharmacologically active xenobiotics as well as to terminate the action of many endogenous substances, evolution has provided metabolic pathways that alter their activity and their susceptibility to excretion. Many cells that act as portals for entry of external molecules into the body eg, pulmonary epithelium, intestinal epithelium contain transporter molecules MDR family [P-glycoproteins], MRP family, others that expel unwanted molecules immediately after absorption. However, some foreign molecules evade these gatekeepers and are absorbed.

Drug metabolism is the metabolic breakdown of drugs by living organisms , usually through specialized enzymatic systems. 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. These pathways are a form of biotransformation present in all major groups of organisms and are considered to be of ancient origin. These reactions often act to detoxify poisonous compounds although in some cases the intermediates in xenobiotic metabolism can themselves cause toxic effects. The study of drug metabolism is called pharmacokinetics.

Phase II Drug Metabolism

Chemical reactions are continually taking place in the body. They are a normal aspect of life, participating in the:. Within the body is a magnificent assembly of chemical reactions, which is well orchestrated and called upon as needed. Most of these chemical reactions occur at significant rates only because specific proteins, known as enzymes, are present to catalyze them, that is, accelerate the reaction. A catalyst is a substance that can accelerate a chemical reaction of another substance without itself undergoing a permanent chemical change.

The liver is the principal site of drug metabolism for review, see [ 1 ]. Although metabolism typically inactivates drugs, some drug metabolites are pharmacologically active—sometimes even more so than the parent compound. An inactive or weakly active substance that has an active metabolite is called a prodrug, especially if designed to deliver the active moiety more effectively. 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.

Drug Metabolism

Topics on Drug Metabolism. All organisms are constantly and unavoidably exposed to xenobiotics including both man—made and natural chemicals such as drugs, plant alkaloids, microorganism toxins, pollutants, pesticides, and other industrial chemicals. Formally, biotransformation of xenobiotics as well as endogenous compounds is subdivided into phase I and phase II reactions. On the other hand, these conjugations also play an essential role in the toxicity of many chemicals due to the metabolic formation of toxic metabolites such as reactive electrophiles. Gene polymorphism of biotransformation enzymes may often play a role in various pathophysiological processes.

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Phase I biotransformation reactions introduce or expose functional groups on the drug with the goal of increasing the polarity of the compound. 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. Within cells, most phase I enzymes are located in the endoplasmic reticulum and thus are enriched in microsomal preparations. Phase I reactions are broadly grouped into three categories, oxidation, reduction, and hydrolysis.

Chemical Reactions

If your institution subscribes to this resource, and you don't have a MyAccess Profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus. Please consult the latest official manual style if you have any questions regarding the format accuracy. All organisms are exposed to foreign chemical compounds xenobiotics in the air, water, and food. To ensure elimination of pharmacologically active xenobiotics as well as to terminate the action of many endogenous substances, evolution has provided metabolic pathways that alter their activity and their susceptibility to excretion. Many cells that act as portals for entry of external molecules into the body eg, pulmonary epithelium, intestinal epithelium contain transporter molecules MDR family [P-glycoproteins], MRP family, others that expel unwanted molecules immediately after absorption.

Он окончательно протрезвел. Ноги и плечо ныли от боли. Беккер с трудом поднялся на ноги, выпрямился и заглянул в темное нутро салона. Среди неясных силуэтов впереди он увидел три торчащие косички. Красная, белая и синяя. Я нашел. В его голове смешались мысли о кольце, о самолете Лирджет-60, который ждал его в ангаре, и, разумеется, о Сьюзан.

 - Хотела бы, но шифровалка недоступна взору Большого Брата. Ни звука, ни картинки. Приказ Стратмора. Все, что я могу, - это проверить статистику, посмотреть, чем загружен ТРАНСТЕКСТ. Слава Богу, разрешено хоть .

Drug metabolism

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 Возможно, - сказал Стратмор, потом нацарапал несколько слов на бумажке и протянул ее Сьюзан.  - Взгляни-ка на. Прочитав написанное, Сьюзан поняла ход мысли коммандера. На бумажке был электронный адрес Северной Дакоты. NDAKOTAARA. ANON.

 Не в этом дело! - воскликнула Сьюзан, внезапно оживившись. Это как раз было ее специальностью.  - Дело в том, что это и есть ключ. Энсей Танкадо дразнит нас, заставляя искать ключ в считанные минуты. И при этом подбрасывает подсказки, которые нелегко распознать. - Абсурд! - отрезал Джабба.  - Танкадо оставил нам только один выход-признать существование ТРАНСТЕКСТА.

Chapter 17

Пожилой человек вдруг поднялся и куда-то побежал, видимо, вызвать скорую. Танкадо явно терял последние силы, но по-прежнему совал кольцо прямо в лицо тучному господину. Тот протянул руку, взял Танкадо за запястье, поддерживая остававшуюся на весу руку умирающего. Танкадо посмотрел вверх, на свои пальцы, на кольцо, а затем, умоляюще, - на тучного господина. Это была предсмертная мольба.

Ей надо было выкупить билет на самолет - если найдется свободное место перед вылетом. Беккер почувствовал, как кровь отхлынула от его лица. - Куда. - В ее трахнутый Коннектикут.  - Двухцветный снова хмыкнул.

Возможно, это хорошо продуманный ход. Сьюзан попыталась осознать то, что ей сообщил коммандер. Она сомневалась, что Танкадо мог передать ключ какому-то человеку, который не приходился ему близким другом, и вспомнила, что в Штатах у него практически не было друзей. - Северная Дакота, - вслух произнесла она, пытаясь своим умом криптографа проникнуть в скрытый смысл этого имени.  - Что говорится в его посланиях на имя Танкадо.

Drug Metabolism

 Мидж… у меня нет никакой жизни. Она постучала пальцем по кипе документов: - Вот твоя жизнь, Чед Бринкерхофф.  - Но, посмотрев на него, смягчилась.

2 Comments

Erika C. 15.03.2021 at 15:46

Drug Metabolism pp Cite as.

Ian C. 21.03.2021 at 17:00

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