Biotransformations metabolism

AP -DDT is rather stable biochemically as well as chemically. Thus, it is markedly persistent in many species on account of its slow biotransformation. Metabolism of p,p -DDT is complex, and there is still some controversy about its specifics. The most important metabolic pathways are shown in Figure 5.2. 

The terminator of drug action is, of course, elimination. Elimination is a composite of excretion (kidney, etc.) and biotransformation (metabolism). The primary measure of drug elimination from the whole body is clearance, CLt, defined as the volume of plasma fluid removed of drug per unit time. It is a direct measure of the loss of the drug from the system and can be calculated from Eq. (3.5) after IV administration of a dose of the drug. 

I. Enzymes—Biotechnology. 2. Biotransformation (Metabolism) 3. Organic compounds—... 

Biotransformation metabolic elimination km = 0.23 d-1 (goldfish, 20°C, 96-h exposure, Sijm Opperhuizen 1988) Bioconcentration, Uptake (k2) and Elimination (k2) Rate Constants ... 

Biotransformation metabolic elimination rate constant from goldfish was estimated to be 0.35 d-1 (Sijm Opperhuizen 1988). 

Biotransformation metabolism half-time 107 h (guppy, Clark Mackay 1991). 

The chemical modification of xenobiotics in the body is called biotransformation, metabolism, or metabolic clearance. Enzymes involved in metabolism are either membrane bound (e.g., endoplasmic reticulum and mitochondria) or freely soluble within the cytosol. Because these metabolic enzymes are not particularly substrate specific, they can metabolize compounds with fairly diverse chemical structures, including some endogenous compounds such as steroids, bile acids, and heme (endobiotics). 

Interactions may occur at one or more of the various states in the pharmacokinetic pathways of drugs in the body (i.e., during absorption, distribution, biotransformation [metabolism], sites of action, and excretion). Each of these states is considered separately. 

Drug biotransformation (metabolism) Use of liver cells, homogenates or isolated cytochrome P450 isozymes to drug study biotransformation... 

The chemical nature and related physicochemical properties largely govern the distribution and elimination, which refers to biotransformation (metabolism) and excretion, of antimicrobial agents. The majority of antimicrobial agents are weak organic electrolytes, either weak acids (penicillins, cephalosporins, sulphonamides) or weak bases (aminoglycosides, lincosamides, macrolides, diaminopyrimidines, metronidazole), while fluoroquinolones, tetracyclines and rifampin are amphoteric compounds, and chloramphenicol and its... 

The biotransformation is the sum of the processes by which a pollutant is subject to chemical change in living organisms. During biotransformation a large number of enzymes and pathways are involved and the common activity of most of them is that they transform lypophilic pollutants into more polar metabolites. Biotransformation (metabolic alteration) of pollutant molecules occurs mainly in the liver, but to some extent also in skin, kidney, placenta, plasma, intestine or brain (Nove et al., 2000). Extrahepatic tissues... 

Elimination covers both excretion (i.e. disappearance of unchanged drug from the body) and biotransformation (metabolism). Some dmgs are excreted in the bile and may be eliminated with the faeces, others are excreted in saliva. General anaesthestics are often excreted by the lungs. However, renal excretion and hepatic biotransformation are the major routes of dmg elimination and these processes will be discussed, together with biliary excretion. 

There are eertain vital faetors that govern the ability of a drug to reach the active site soon after its administration through various modes known to us. These faetors essentially include absorption, distribution, biotransformation (metabolism) and elimination. However, in all these instances, the drug molecule has to eross a few biologieal membrane in one form or the other. These factors shall now be treated briefly with appropriate typieal examples wherever neeessary. 

Biotransformation (Metabolism.) 4. Xenoblotics—Metabolic detoxication. I. Singh, Vedpal, 1951-. II. Series. 

There should be adequate information on the absorption, distribution, biotransformation, metabolism and elimination of the chemical in the body. This type of information will indicate what tissues to sample, for what compound (parent chemical or a metabolite) and at what time. The latter issue is very important with chemicals that are eliminated rapidly (i.e., those with short half-lives). 

Biotransformation (Metabolism) I. Roberts, Stanley M. TP248.27.M53157 1995... 

In this chapter, the basics of MT-catalyzed biotransformations will be reviewed, including non-natural variations. Special emphasis is given to reactions connected to preceding or subsequent steps as pointed out above. However, very few cascaded in vitro processes have been reported so far, as current trends are more directed to multistep in vivo biotransformations (metabolic engineering, synthetic biology). 

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