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 majority of metabolic processes that involve drugs occur in the liver, as the enzymes that facilitate the reactions are concentrated there.
What does drug metabolism mean?
Drug metabolism is the chemical alteration of a drug by the body. (See also Introduction to Administration and Kinetics of Drugs.) Some drugs are chemically altered by the body (metabolized).
How does metabolism affect drugs?
Drug and Food Interactions.
When they increase the enzyme’s metabolic function, the drug’s therapeutic effects may be decreased. When they decrease the enzyme’s metabolic function, the drug’s benefits may be compromised by intolerability. Your metabolic enzyme systems change throughout your lifetime.
Why do I metabolize drugs so quickly?
Because of their genetic makeup, some people process (metabolize) drugs slowly. As a result, a drug may accumulate in the body, causing toxicity. Other people metabolize drugs so quickly that after they take a usual dose, drug levels in the blood never become high enough for the drug to be effective.
What does rapid metabolizer mean?
Rapid or Ultrarapid Metabolizers. These enzymes are very active, often breaking down drugs before they can have any effect. If you metabolize a drug in this way, you may require a higher dose in order for the drug to work properly.
What is the main 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.
What are the four stages of drug metabolization?
The four stages are absorption, distribution, metabolism, and excretion.
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 is oxidation in drug metabolism?
In most cases, an oxygen atom is retained in the metabolite, although some reactions, such as dealkylation, result in loss of the oxygen atom in a small fragment of the original molecule. Oxidation reactions are catalysed by a diverse group of enzymes, of which the cytochrome P450 system is the most important.
What is first pass metabolism of drug?
The first-pass metabolism or the first-pass effect or presystemic metabolism is the phenomenon which occurs whenever the drug is administered orally, enters the liver, and suffers extensive biotransformation to such an extent that the bioavailability is drastically reduced, thus showing subtherapeutic action (Chordiya …
What the body does to the drug?
Pharmacokinetics, sometimes described as what the body does to a drug, refers to the movement of drug into, through, and out of the body—the time course of its absorption, bioavailability, distribution, metabolism, and excretion.
What causes drug intolerance?
Two effects most often cause drug intolerance: changes in the gut microbiome and the potential cross-reactivity of the antibiotic itself with other organs, typically the nervous system.
Does weight affect drug metabolism?
Physiological alterations to the body, such as increased adipose (fat) tissue, can affect distribution, metabolism and clearance of drugs from the body.
What does it mean to be a poor metabolizer of a drug?
Poor metabolizer: Patients who are poor metabolizers experience a very slow breakdown of medications, making side effects more pronounced. That means standard doses of certain medications may not work as intended. … Patients are likely to metabolize medication normally and medication is likely to work as intended.
What drugs are metabolized by cyp2c19?
CYP2C19 is the principal enzyme involved in the hepatic metabolism of drugs such as antimalarial (proguanil), oral anticoagulants (R-warfarin), chemotherapeutic agents (cyclophosphamide), anti-epileptics (S-mephenytoin, diazepam, phenobarbitone), antiplatelets (clopidogrel), proton pump inhibitors (omeprazole, …
What drugs are metabolized by cyp2b6?
Drugs metabolized mainly by CYP2B6 include artemisinin, bupropion, cyclophosphamide, efavirenz, ketamine, and methadone. CYP2B6 is one of the most polymorphic CYP genes in humans and variants have been shown to affect transcriptional regulation, splicing, mRNA and protein expression, and catalytic activity.