Even though drug metabolism in numerous locations within the body, the liver is the primary organ involved in the modification and removal of drug compounds. Pharmacokinetics is a collection of pharmacological processes that measure how much drug is available throughout the human body over time.
How does drug metabolism work?
Excretion involves elimination of the drug from the body, for example, in the urine or bile. 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.
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.
Why is drug metabolism important?
The metabolism of a drug can have important consequences on its therapeutic effect or its toxicity. For this reason, early assessments of metabolic pathways in man help to foresee interindividual variation in drug response and elimination due to metabolism.
What is the definition of pharmacokinetics?
Listen to pronunciation. (FAR-muh-koh-kih-NEH-tix) The activity of drugs in the body over a period of time, including the processes by which drugs are absorbed, distributed in the body, localized in the tissues, and excreted.
What are the consequences of drug metabolism?
In general, the metabolism of a drug decreases its therapeutic effect. The majority of drugs are metabolized to increase their water solubility to allow elimination in urine or bile. However some drugs are metabolized into active compounds first before subsequent metabolism to inactive compounds and be excreted.
What are the factors affecting drug metabolism?
Many factors affect the rate and pathway of metabolism of drugs, and the major influences can be sub-divided into internal (physiological and pathological) and external (exogenous) factors as indicated below: Internal: species, genetic (strain), sex, age, hormones, pregnancy, disease. External: diet, environment.
What are the two major goals of drug metabolism?
The purpose of metabolism in the body is usually to change the chemical structure of the substance, to increase the ease with which it can be excreted from the body. Drugs are metabolized through various reactions including: Oxidation. Reduction.
What is the main site of drug metabolism?
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.
What are the three phases of metabolism?
The metabolism of xenobiotics is often divided into three phases:- modification, conjugation, and excretion.
What factors can affect drug metabolism in an elderly?
Aging results in a number of significant changes in the human liver including reductions in liver blood flow, size, drug-metabolizing enzyme content, and pseudocapillarization. Drug metabolism is also influenced by comorbid disease, frailty, concomitant medicines, and (epi)genetics.
What is metabolism and its function?
Metabolism is a term that is used to describe all chemical reactions involved in maintaining the living state of the cells and the organism. Metabolism can be conveniently divided into two categories: Catabolism – the breakdown of molecules to obtain energy. Anabolism – the synthesis of all compounds needed by the …
What are the four stages of drug metabolization?
The method by which a drug is administered, along with other factors, determines the speed of onset of effects. Drugs undergo four stages within the body: absorption, distribution, metabolism, and excretion.
What drug does to the body is called?
Pharmacodynamics, described as what a drug does to the body, involves receptor binding, postreceptor effects, and chemical interactions. Drug pharmacokinetics determines the onset, duration, and intensity of a drug’s effect.
How are drugs absorbed?
Introduction to Drug Absorption. Absorption is the process of delivering a drug into the blood stream. Absorption can be accomplished by administering the drug in a variety of different ways (e.g. orally, rectally, intra-muscularly, subcutaneously, inhalation, topically, etc.).
What is pharmacokinetics and why is it important?
Pharmacokinetics is a science that studies how certain substances affect a living organism when administered. This particular science determines what happens to a drug from the time it is administered throughout its circulation within the body and to the moment when it is ultimately eliminated from the body.