What are the four cornerstones of xenobiotic pharmacokinetics?

What are the four cornerstones of xenobiotic pharmacokinetics?

This chapter examines the four cornerstones of xenobiotic pharmacokinetics—absorption, distribution, metabolism, and excretion (ADME)—on a physiological and biochemical basis.

What is xenobiotic pharmacokinetics?

INTRODUCTION. ++ Pharmacokinetics is the study of the absorption, distribution, metabolism, and excretion of xenobiotics. Xenobiotics are substances that are foreign to the body and include natural or synthetic chemicals, drugs, pesticides, environmental agents, and industrial agents.

What are xenobiotics and their examples?

Xenobiotics are compounds that are foreign to an organism or are not part of its normal nutrition. Examples of Xenobiotics are compounds that include drugs, food additives, and environmental pollutants. ... Likewise, Xenobiotic transporters also affect the duration that drugs are present in the body.

What are xenobiotic compounds?

A xenobiotic (Greek, xenos "foreign"; bios "life") is a compound that is foreign to a living organism. ... A xenobiotic is a chemical substance found within an organism that is not naturally produced or expected to be present within the organism.

Is caffeine a xenobiotic?

Yes. Xenobiotics (ie. caffeine) affect liver enzymes and this starts the clock.

Is DDT a xenobiotic?

1,1,1-Trichloro-2,2-bis-(4'-chlorophenyl)ethane (DDT), the first of the chlorinated organic insecticides, is a widely distributed and persistent xenobiotic contaminant in the environment. DDT is not metabolized very rapidly by animals; instead, it is deposited and stored in the fatty tissues.

What is not a xenobiotic?

Xenobiotics are chemicals found but not produced in organisms or the environment. Some naturally occurring chemicals (endobiotics) become xenobiotics when present in the environment at excessive concentrations. The “xeno” in “xenobiotics” comes from the Greek word xenos meaning guest, friend, or foreigner.

Why xenobiotics are recalcitrant?

But some xenobiotics are recalcitrant in nature because of various reasons. Some of them cannot be used as substrate by microbes, some cannot transport them due to absence of transporting enzymes and some are in accessible to microbes due to larger structure and insolubility.

Is lead a xenobiotic?

Throughout our life span, humans are also exposed to xenobiotic metals from natural and anthropogenic sources, including aluminum, arsenic, cadmium, lead, and mercury.

What is xenobiotic degradation?

In other words, defined as the ability of microorganisms to convert toxic chemicals (xenobiotics) to simpler non-toxic compounds by synthesis of certain enzymes • Biodegradation of xenobiotics can be affected by substrate specificity, nutrition source, temperature, pH etc. ...

Is alcohol a xenobiotic?

Alcohol and xenobiotics share the same oxidative microsomal pathway, which is mainly located in the endoplasmic reticulum of hepatocytes. This pathway involves enzymes that belong to the super family of cytochrome P450 and allows to explain a lot of pharmacokinetic or toxic interactions between alcohol and xenobiotics.

Why are drugs referred to as xenobiotics?

The term xenobiotic is derived from the Greek words ξένος (xenos) = foreigner, stranger and βίος (bios) = life, plus the Greek suffix for adjectives -τικός, -ή, -όν (-tikos, -ē, -on). ... Xenobiotics may be grouped as carcinogens, drugs, environmental pollutants, food additives, hydrocarbons, and pesticides.

What is xenobiotic stress?

Description. Xenobiotics such as drugs, chemotherapy, food additives, and environmental pollutants are foreign chemical compounds to our biological system. These compounds generate several free radicals that lead to increase the oxidative stress in the cells. ... Toxicity of xenobiotics.

Are drugs xenobiotics?

Drugs can be considered a subset of xenobiotics, that is, natural compounds of exogenous origin that may find their way into the human body. Other important classes of xenobiotics are potentially toxic plant alkaloids or fungal toxins.

How xenobiotics can cause toxicity?

In general, biotransformation results in detoxification of xenobiotics and is accompanied by the formation of chemically stable metabolites. However, in some cases, these reactions can convert xenobiotics to toxic metabolites that are chemically reactive (22).

What is Xeno biochemistry?

The biochemistry of organic compounds foreign to the organism. From: xenobiochemistry in Oxford Dictionary of Biochemistry and Molecular Biology » Subjects: Science and technology — Chemistry.

What Toxicology means?

Toxicology is traditionally defined as "the science of poisons." Over time, our understanding of how various agents can cause harm to humans and other organisms has increased, resulting in a more descriptive definition of toxicology as "the study of the adverse effects of chemical, physical, or biological agents on ...

What is cytochrome P450 system?


What happens when CYP450 is inhibited?

Inhibitors block the metabolic activity of one or more CYP450 enzymes. The extent to which an inhibitor affects the metabolism of a drug depends upon factors such as the dose and the ability of the inhibitor to bind to the enzyme. ... 17 Inhibitory effects usually occur immediately.

What are CYP450 inhibitors?

CYP450 enzymes are so named because they are bound to membranes within a cell (cyto) and contain a heme pigment (chrome and P) that absorbs light at a wavelength of 450 nm when exposed to carbon monoxide. ... Drugs that cause CYP450 drug interactions are referred to as either inhibitors or inducers.

What is the goal of the P450 system?

Cytochrome P450 enzymes also function to metabolize potentially toxic compounds, including drugs and products of endogenous metabolism such as bilirubin, principally in the liver. The Human Genome Project has identified 57 human genes coding for the various cytochrome P450 enzymes.

What is the reaction scheme of P450?

Many P450 reactions involve multiple steps, i.e. a product of one reaction is a substrate for a subsequent reaction by the same enzyme. An issue is the degree to which the two reactions are “processive,” i.e. the extent to which the first product is released by the enzyme and must re-bind to generate the final product.

How do you remember CYP450 inhibitors?

CYP450 enzymes can be inhibited or induced by some drugs, resulting in significant drug interactions that can cause unanticipated adverse reactions or therapeutic failures. An easy way to remember the mnemonic is; CRAP GPs spend all day on SICKFACES.com.

Is alcohol a CYP450 inducer or inhibitor?

In addition to further metabolism by ADH in the liver, alcohol is also metabolized by CYP450 enzymes, mainly CYP2E1. Alcohol is a substrate of CYP2E1, and depending on the frequency of alcohol intake, it can also be either an inducer or inhibitor of CYP2E1.

What are cyp450 inducers?

Enzyme Induction CYP enzyme inducers increase the rate of hepatic metabolism, usually through increased transcription of mRNA, and decrease serum concentrations of other drugs metabolized by the same hepatic isoenzyme.

What drugs increase the effect of alcohol?

Alcohol and Painkillers: Includes: Vicodin, Xanax, Oxycontin, Percocet, Demerol, Norco, etc. Mixing painkillers with alcohol is dangerous. The mixture of these two substances can lead to intensified sedative effects and respiratory depression.

What is the effects of alcohol for the pharmacokinetic properties of drugs?

Alcohol can affect the pharmacokinetics of drugs by altering gastric emptying or liver metabolism (by inducing cytochrome P450 2E1). Drugs may affect the pharmacokinetics of alcohol by altering gastric emptying and inhibiting gastric alcohol dehydrogenase.

What medication can you not drink alcohol with?

10 Medications You Shouldn't Mix With Alcohol

  • Painkillers.
  • Anti-anxiety and sleeping pills.
  • Antidepressants and mood stabilizers.
  • ADHD medications.
  • Antibiotics.
  • Nitrates and other blood pressure drugs.
  • Diabetes medications.
  • Coumadin.

Does alcohol inhibit CYP3A4?

Although alcohol is known to induce CYP3A4 leading to increased ART drug metabolism, this is the first report on alcohol-CYP3A4 physical interaction resulting in altered binding and metabolism of an ART. This is very important finding in context with the report that alcohol decreases the response to ART.

What is a disulfiram like reaction with alcohol?

A disulfiram-like drug is a drug that causes an adverse reaction to alcohol leading to nausea, vomiting, flushing, dizziness, throbbing headache, chest and abdominal discomfort, and general hangover-like symptoms among others.