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Biotransformation decreased activity

GBL was found to hydrolyse rapidly in plasma, with a half-life of approximately 1 minute. In spite of this rapid biotransformation, oral activity of GBL was almost identical to that achieved after intravenous administration of GHB. Apparently, GBL is not subjected to any of the processes which decrease peak plasma concentrations, viz gastrointestinal degradation, capacity-limited transport and first-pass metabolism. The use of lactone analogs as a general approach to improve the bioavailability and/or rate of absorption of other hydroxy-acids, e.g. prostaglandins, has, however, not been tested. [Pg.310]

Mechanisms Fluorouracil is biotransformed to 5-fluoro-2 -deoxyuridine-5 -monophos-phate (5-FdUMP). which inhibits thymidylate synthase and leads to thymineless death of cells. Tumor cell resistance mechanisms include decreased activation of 5-FU, increased thymidylate S)mthase activity, and reduced drug sensitivity of this enzyme. [Pg.481]

From the simulation results in Figure 4, a maximum PAC concentration of 740 mM was predicted at 81 h together with by-products acetoin (55 mM) and acetaldehyde (10 mM). The activity of PDC decreased rapidly throughout the biotransformation with only 5% residual activity when feeding was terminated. [Pg.28]

Apart from the site and route of administration, formulation, dosage, and duration of treatment, biotransformation is often also affected by several other factors including age, species differences, sex differences, diet, diseases, hormones, and environment. The activity of the liver microsomal enzymes is low in newborns and aging animals resulting in a slower rate of biotransformation. Species differences in dosage and response are often due to biotransformation differences. Inadequate protein intake approaching starvation may also decrease the rate of biotransformation (12). Diseases of the liver sometimes also interfere with the normal biotransformation capacity. In addition, increase in biotransformation may occur at high body temperatures because of an increase in the metabolic rate. [Pg.20]

The biodisposition of sedative-hypnotics can be influenced by several factors, particularly alterations in hepatic function resulting from disease or drug-induced increases or decreases in microsomal enzyme activities (see Chapter 4 Drug Biotransformation). [Pg.514]

Treatment of violacein with the enzyme HRP-VI afforded azetine 647, a structural analogue of violacein. This biotransformed violacein exhibited a fourfold lower cytotoxicity, indicating a decrease in antitumor activity as compared to violacein itself <2001JM0463>. [Pg.96]

Biodegradation average rate of biodegradation 71.0 mg COD g- h- based on measurements of COD decrease using activated sludge inoculum with 20-d of adaptation to the substrate (Pitter 1976 quoted. Scow 1982). Biotransformation ... [Pg.236]


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See also in sourсe #XX -- [ Pg.152 , Pg.153 ]




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