Drug metabolism is the chemical alteration of a drug by the body. 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. The liver’s primary mechanism for metabolizing drugs is via
a specific group of cytochrome P-450 enzymes. The level of these cytochrome P-450 enzymes controls the rate at which many drugs are metabolized. The capacity of the enzymes to metabolize is limited, so they can become overloaded when blood levels of a drug are high (see
Genetic Makeup and Response to Drugs
Genetic Makeup and Response to Drugs ). Many substances (such as drugs and foods) affect the cytochrome P-450 enzymes. If these substances decrease the ability of the enzymes to break down a drug, then that drug's effects (including side effects) are increased. If the substances
increase the ability of the enzymes to break down a drug, then that drug's effects are decreased. Because metabolic enzyme systems are only partially developed at birth, newborns have difficulty metabolizing certain drugs. As people age, enzymatic activity decreases, so that older people, like newborns, cannot metabolize drugs as well as younger adults and children do (see
Aging and Drugs Aging and Drugs ).
Consequently, newborns and older people often need smaller doses per pound of body weight than do young or middle-aged adults. CLICK HERE FOR THE
PROFESSIONAL VERSION  Copyright © 2022 Merck & Co., Inc., Rahway, NJ, USA and its affiliates. All rights reserved. Want a FREE PDF version of This Article? Complete the form below and we will email you a PDF version of "What Is ADME?" Company Type* Job Function* Would you like to receive further email communication from Technology Networks? Technology Networks Ltd. needs the contact information you provide to us to contact you about our products and services. You may unsubscribe from these communications at any time. For information on how to unsubscribe, as well as our privacy practices and commitment to protecting your privacy, check out our Privacy Policy ADME is the abbreviation for Absorption, Distribution, Metabolism and Excretion. ADME studies are designed to investigate how a chemical (e.g. a drug compound) is processed by a living organism. Toxicology tests are often a part of this process, yielding the acronym ADMET. What are the four steps of pharmacokinetics?Pharmacokinetics is a specific branch of pharmacology that studies what the body does to a drug. Pharmacokinetic
studies evaluate:
ADME are the four steps of pharmacokinetics. Let us break down what each of these steps involves. AbsorptionAbsorption describes how a chemical enters the body. Absorption relates to the movement of a chemical from the
administration site to the bloodstream. There are four main routes of administration:
Only injected compounds
enter directly into the systemic circulation. For drugs administered through ingestion, inhalation or dermal contact, the chemicals must cross a membrane before entering the bloodstream.
The route of administration influences bioavailability, which is a measure of how much of a drug is absorbed in an unchanged form. You can find the bioavailability by measuring the plasma drug concentration over time. Only intravenous administration results in 100% bioavailability. Drugs administered in other ways will have reduced bioavailability. Not all of the compound will make it into the bloodstream. For instance, a drug that is ingested first undergoes metabolism during which some of the drug is excreted before entering the bloodstream. DistributionOnce a drug has been absorbed, it moves from the absorption site to tissues around the body. This distribution from one part of the body to another is typically accomplished via the bloodstream, but it can also occur from cell-to-cell. Researchers examine where the chemical travels to, the rate at which it arrives to certain sites, and the extent of
the distribution to help determine efficacy. Some compounds move easily, while others do not. Factors such as blood flow, lipophilicity, tissue binding, and molecular size influence distribution. MetabolismDrug metabolism is the biotransformation of a drug by organs or tissues (primarily the liver, kidney, skin or digestive tract) so that the drug can be excreted. To facilitate removal via feces or urine, the drug compound is altered to become more water-soluble. Chemical metabolism can result in toxicity, for instance by creating damaging biproducts or a toxic metabolite. Scientists map out the specific metabolic pathways of a drug candidate, something called adverse outcome pathways (AOPs). AOPs provide data needed to determine the potential safety or toxicity of a drug. Drug metabolism and interaction data provide researchers with the information they need to determine the likelihood of drug–drug interactions (DDIs). Anticipating drug interactions is essential for safe pharmaceutical development. ExcretionExcretion is the process by which the metabolized drug
compound is eliminated from the body. Researchers want to know how rapidly the drug is excreted and what pathway it takes to exit the body. Most drug excretion occurs as feces or urine. Other excretion methods include through the lungs or in sweat through the skin. Molecular size and charge influence the excretion pathway. Not every drug compound is fully excreted. When the chemical or metabolic by-products bioaccumulate, adverse effects can occur. Lipid-soluble compounds are more prone to bioaccumulate compared to water-soluble compounds. Why is ADME important?In drug discovery and development, researchers must examine the activity of a drug in the body to assess safety and toxicity. Drug metabolism and pharmacokinetics studies, such as ADME and toxicology studies, are a critical step in this process. The data collected tells researchers if a drug is viable and provides specific targets for future research and development. Advances in the field have precipitated the rise of personalized ADME approaches, where factors such as a patient's genome or even the time of day during which drugs are administered are considered. Computational techniques are often used to assist these more precise studies. What is the term for the body's process of absorbing distributing metabolizing and excreting a drug?25.1 Introduction. Pharmacokinetics, derived from the Greek words pharmakon (drug) and kinetikos (movement), is used to describe the absorption, distribution, metabolism, and excretion of a compound.
What is the term for the body's process of absorbing distributing metabolizing and excreting a drug quizlet?Pharmacokinetics. is the process of drug movement throughout the body that is necessary to achieve drug action. The four processes are absorption, distribution, metabolism (or biotransformation), and excretion (or elimination)
What is it called when a drug is excreted from the body?Drug excretion is the removal of drugs from the body, either as a metabolite or unchanged drug. There are many different routes of excretion, including urine, bile, sweat, saliva, tears, milk, and stool.
What is meant by drug metabolism and excretion?Metabolism is the conversion of generally more lipophilic xenobiotic compounds to hydrophilic metabolites that can be eliminated from the body via excretion2. Metabolism of a drug involves enzymes and several investigative studies may be needed to identify major metabolites and relevant metabolic pathways.
|
What is the term for the bodys process of absorbing distributing metabolizing and excreting a drug?
zusammenhängende Posts
Urheberrechte © © 2024 WIKIFI Inc.
