An introduction to the excretion and elimination of toxicants and their metabolites

The faster the rate of glomerular filtrationthe faster the polar xenobiotics are eliminated from the body. This means that they will be easily ablorbed and dispursed among the tissue. Excretion via breast milk may affect the breastfeeding infant see Table: The main purpose of this study is to determine whether induced perspiration can be used clinically to facilitate decorporation of the range of both parent OCPs as well as their metabolites.

Increased tolerance to subsequent exposures of a toxicant, in some instances, is due to enzyme induction initiated by the previous exposure. If this is true then passage through the pores will be hindered by the size of the larger molecule.

Both the Loop of Henley and collecting duct are used to establish these osmolar gradients. In addition to excretion via the bile, highly lipophilic chemicals that are recalcitrant to metabolism may be excreted as the parent chemical by a number of alternate routes, although in terms of the overall excretion of toxicant these are generally of minor importance compared to urine and bile.

Polar substances usually do not bind with the plasma proteins and thus can be filtered out of the blood into the tubule filtrate. Ortho methyl substitution rather than longer chain substitution on the phenyl ring s of triphenyl phosphates increases the capability to cause OPIDN.

Removal of organochlorine compounds has also been facilitated by specific interventions which interrupt the enterohepatic circulation [ 75258 ].

Another determining factor will be if a molecule is bound to a large molecule. Other mechanisms involves the use of a mechanism that is called ion trapping. The rate of elimination usually depends on the concentration of the compound. Excretion into milk can be important since toxicants can be passed with milk to the nursing offspring.

This can occur with liver disease, which usually causes a decrease in bile flow. If the urine is alkaline, weak acids are more ionized and thus excreted to a great extent. Substitution at other sites on the ortho-substituted ring decreases the neurotoxicity.

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Secretions include organic bases, which occur in the pars recta of the proximal tubule. The main routes of excretion are via urine, feces, and exhaled air.

In this case, drugs may be given orally to bind substances excreted in the bile. Their accumulation in the body occurs in both adipose tissue and lipid layers of the skin.

This is due to the very close proximity of capillary and alveolar membranes, which are thin and allow for the normal gaseous exchange that occurs in breathing. Water and chloride ions are passively reabsorbed by the establishment of osmotic and electrochemical gradients.

Thus they are able to diffuse across the membranes of the tubule. There are two phases of metabolism. Excretion sites are proximal tubules, glomeruli, medulla, papilla, and loop of Henle.

Therefore, the major subgroups producing OPIDN are phosphates derivatives of phosphoric acid, which has four oxygens on the phosphorusphosphonates derivatives of phosphonic acid, which has three oxygens on the phosphorusphosphoramidates derivatives of phosphoramidic or phosphorodiamidic acids, with one or two nitrogens and two or three oxygens on the phosphorusor phosphorofluoridates three oxygens and a fluoride on the phosphorus Figure Once a substance has been excreted by the liver into the bile, and subsequently into the intestinal tract, it can then be eliminated from the body in the feces, or it may be reabsorbed.

The first step that occurs in the kidney deals with the nephron, which is the functional unit of the kidney. Some Drugs Contraindicated for Breastfeeding Mothers.

Essay/Term paper: Excretion and elimination of toxicants and their metabolites

Substances that are chemically similar to calcium can also be excreted into milk along with calcium. The liver receives the portal circulation and is the organ most commonly involved with intoxication and detoxification.Excretion is the removal of xenobiotics from the blood and their return to the external environment via urine, feces, exhalation, etc.

INTRODUCTION The disposition of a chemical or xenobiotic is defined as the composite actions of its absorption, distribution, biotransformation, and elimination.

Understanding cocaine and metabolites urinary excretion following smoking is important for interpretation of urine test results in judicial, workplace and treatment settings.

In National Institute on Drug Abuse approved studies on a secure research unit, six subjects smoked placebo, 10, 20, and Jan 26,  · Toxicants or their metabolites can be eliminated from the body by several routes. The main routes of excretion are via urine, feces, and exhaled air.

Thus, the primary organ systems involved in excretion are the urinary system, gastrointestinal system and respiratory system. Drug excretion. The kidneys are the primary routes for drug excretion from the body. Drugs reach the kidney in either their active form or as a drug metabolite after biotransformation in the liver.

In either case, it is the kidney’s responsibility to filter the drug from the circulation and excrete it. Except in simple life forms, elimination of toxicants, including pesticides and their metabolites, is part of a specialized system that, in addition to elimination, maintains the balance of water, minerals, and other substances necessary for terrestrial life.

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If metabolite is active or reactive, increased drug effects or toxicity Enzyme inhibition Inhibition of drug metabolism by a concurrently administered drug can lead to drug accumulation & toxicity and also potentiate the action of unrelated drugs.

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An introduction to the excretion and elimination of toxicants and their metabolites
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