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  • 1
    Electronic Resource
    Electronic Resource
    Sulphation of the heterocyclic amine 1,2,3,4-tetrahydroisoquinoline in the human liver and intestinal mucosa: interindividual variability (1997)
    Springer
    Archives of toxicology 71 (1997), S. 477-481 
    Details
    ISSN: 1432-0738
    Keywords: Key words Sulphotransferase ; Liver ; Intestine ; Man ; Variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The sulphation rate of 1,2,3,4-tetrahydroisoquinoline (TIQ) was measured in the human liver and in the intestinal mucosa isolated from the transverse colon, ileum and duodenum. The rate (mean ± SD) of hepatic TIQ sulphation was 500 ± 174 pmol/min per mg in women (n=61) and 591 ± 201 in men (n=39; P=0.0087), varying over one order of magnitude in men and women. The sulphation rate of testosterone showed the same sex-dependent pattern and was correlated (r=0.6055; P〈0.001) with that of TIQ. The frequency distribution of TIQ sulphation rate in human liver was bimodal: 70% of the population fell into the low-activity subgroup and the remaining 30% feel into the high-activity subgroup. In the colon (n=56), the rate of TIQ sulphation was 30.4 ± 15.6 pmol/min per mg and the values were similar in men and women (29.8 and 30.9 pmol/min per mg, respectively) but, varied over one order of magnitude and correlated (r=0.7231; P〈0.001) with that of 4-nitrophenol. The rate of TIQ sulphation changed along the human bowel and mean (±SD) estimates for duodenum, ileum and transverse colon were 444 ± 25, 182 ± 87  and 30.4 ± 15.6 pmol/min per mg, respectively. The present results are consistent with the view that the heterocyclic amine TIQ is sulphated in the human liver and intestinal mucosa. TIQ-sulphotransferase activity varies among subjects and is mostly associated with the liver and duodenum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050415
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  • 2
    Electronic Resource
    Electronic Resource
    Placental transfer of pinazepam and its metabolite N-desmethyldiazepam in women at term (1984)
    Springer
    European journal of clinical pharmacology 27 (1984), S. 307-310 
    Details
    ISSN: 1432-1041
    Keywords: pinazepam ; placental transfer ; N-desmethyldiazepam ; benzodiazepines ; pregnancy ; delivery ; plasma concentration ; neonate ; breast milk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Placental transfer of pinazepam and its metabolite N-desmethyldiazepam was investigated in 25 pregnant women at term. Pinazepam was administered orally as a single (10 mg) dose to 13 women, or in multiple doses of 5 mg daily to 12 women. The dose-delivery interval ranged between 1 and 26 h for the single dose, and the period between the last of the multiple doses and delivery was 1.4 to 24 h. Pinazepam and N-desmethyldiazepam were measured in plasma obtained from the umbilical vein and from the mother, at delivery. Pinazepam was only detectable in plasma after the 10 mg dose. The drug did not reach an apparent equilibrium between fetal and maternal plasma. The average (±SEM) cord/maternal ratio of plasma pinazepam concentrations was 0.64±0.07. N-desmethyldiazepam was detectable on each occasion. Its concentration in the plasma from the cord vein became higher than that in the maternal specimens 1–2 h after administration of the parent drug. Little N-desmethyldiazepam was excreted in breast milk.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00542165
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  • 3
    Electronic Resource
    Electronic Resource
    Plasma protein binding of furosemide in the elderly (1987)
    Springer
    European journal of clinical pharmacology 32 (1987), S. 199-202 
    Details
    ISSN: 1432-1041
    Keywords: furosemide ; plasma protein binding ; old age ; youth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The protein binding of furosemide was investigated in plasma from 22 old and 11 young subjects by equilibrium dialysis. The unbound fraction of furosemide was 3.16% in plasma from the elderly and 1.71% in plasma from the young. A significant correlation was found between the unbound fraction of furosemide and the plasma concentration of albumin. The average number of binding sites was 3.8 (elderly) and 2.7 (young) 10−6 mol/g albumin. The average association constant (K) was 4.3 (elderly) and 4.2 (young) 105 M−1. By increasing the concentration of furosemide up to 200 µg/ml buffer the unbound fraction of the drug rose to 5.2% (elderly) and 3.5% (young).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00542196
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  • 4
    Electronic Resource
    Electronic Resource
    Pinazepam: A precursor of N-desmethyldiazepam (1982)
    Springer
    European journal of clinical pharmacology 22 (1982), S. 225-228 
    Details
    ISSN: 1432-1041
    Keywords: pinazepam ; N-desmethyldiazepam ; kinetics ; metabolism ; human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The plasma profile of a single oral dose of pinazepam 10 mg was studied in 6 healthy male volunteers, aged 26 to 31 years. The concentrations of the parent compound and of its metabolite in plasma were measured by gas-chromatography. The peak plasma levels of pinazepam was 36.8±5.1 ng/ml and of N-desmethyldiazepam 150±13.3 ng/ml. The plasma concentration of the metabolite become higher than that of the parent compound shortly after administration, suggesting that pinazepam acts as a prodrug.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00545219
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  • 5
    Electronic Resource
    Electronic Resource
    Morphine glucuronidation in human fetal and adult liver (1982)
    Springer
    European journal of clinical pharmacology 22 (1982), S. 553-558 
    Details
    ISSN: 1432-1041
    Keywords: glucuronidation ; morphine ; UDP-glucuronyltransferase ; adult liver ; fetal liver ; enzyme heterogeneity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The glucuronyltransferase activity towards morphine was measured in microsomes isolated from liver specimens obtained from human fetuses and cancer patients. All the fetal livers investigated had measurable UDP-glucuronyltransferase activity towards morphine. There was no correlation between the gestational age (15 to 27 weeks) and the glucuronidation rate. The mean value of the enzymatic activities was higher in fetal livers obtained by hysterotomy (0.20 nmoles×min−1×mg−1) than in livers obtained after induced abortion (0.11 nmoles×min−1×mg−1). The average rate of glucuronidation in microsomes from adult liver (mean 1.15 nmoles×mint-1×mg−1) was 6 to 10 times higher than in the fetal liver microsomes. Together with previous investigations on human adult and fetal liver glucuronidation, the present results support the theory of heterogeneity of human UDP-glucuronyltransferase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00609630
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  • 6
    Electronic Resource
    Electronic Resource
    (+) and (−) terbutaline are sulphated at a higher rate in human intestine than in liver (1993)
    Springer
    European journal of clinical pharmacology 45 (1993), S. 483-487 
    Details
    ISSN: 1432-1041
    Keywords: Terbutaline ; Drug metabolism ; sulphotransferases ; liver ; intestine ; lung ; man ; stereoselective conjugation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The sulphation of (+) and (−) terbutaline was investigated in specimens of human intestinal mucosa isolated from the duodenum, ileum, ascending colon and sigmoid colon and in specimens of liver and lung. The lung specimens came from 8 current smokers and 11 ex-smokers, the latter having stopped at least 3 months before surgery. The rates (pmol·min−1·mg protein−1) of (+) and (−) terbutaline sulphation were 1195 and 948 (duodenum), 415 and 317 (ileum), 268 and 166 (ascending colon), 263 and 193 (sigmoid colon) and 45 and 34 (liver), respectively. Terbutaline sulphotransferase was more active in the small and large intestine than in the liver. In the lung, the rate of (+) terbutaline sulphation was 118 (ex-smokers) and 82 (smokers), and for (−) terbutaline it was 82 (ex-smokers) and 56 (smokers). In the gut, the activity of catechol sulphotransferase was significantly correlated with that of (+)- and (−)- terbutaline sulphotransferase whereas no correlation was found with phenol sulphotransferase. This correlation, the finding of the higher activity of terbutaline sulphotransferase in gut than in liver, and the pronounced thermal inactivation of the enzyme, are all consistent with the view that catechol sulphotransferase has a role in the sulphation of terbutaline.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00315522
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  • 7
    Electronic Resource
    Electronic Resource
    Distribution of UDP-glucuronosyltransferase and its endogenous substrate uridine 5′-diphosphoglucuronic acid in human tissues (1991)
    Springer
    European journal of clinical pharmacology 41 (1991), S. 345-350 
    Details
    ISSN: 1432-1041
    Keywords: UDP-glucuronosyltransferase ; Drug glucuronidation ; 5′-uridine diphosphoglucuronic acid ; human tissues ; enzyme kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The activity of UDP-glucuronosyltransferase (UDPGT) and the concentration of its endogenous substrate, 5′-diphosphoglucuronic acid (UDPGA), have been measured in human liver, kidney, lung and intestinal mucosa. The activity of UDPGT was tissue- and substrate-dependent. The liver/kidney and liver/intestine ratios for UDPGT varied over one order of magnitude with three substrates. The highest activity of UDGPT in extrahepatic tissues was in the kidney, with 1-naphthol as substrate; it was about half of the hepatic activity. The concentration (μmol · kg−1) of UDPGA was 279 (liver), 17.4 (kidney), 19.3 (intestinal mucosa) and 17.2 (lung), it was at least 15-fold higher in liver than the other tissues, and the concentration in kidney, lung and intestinal mucosa was similar. The kinetics of UDPGT in a liver homogenate at varying concentrations of UDPGA and fixed concentration of 1-naphthol, ethinyloestradiol, and morphine was also measured. The apparent kM for UDPGT depended upon the chemical nature of the UDPGA-acceptor substrate; average values of kM were 63, 300, and 700 μmol · 1−1 for 1-naphthol, ethinyloestradiol and morphine respectively. These values are, respectively, lower, similar to and higher than the hepatic concentration of UDPGA. Under certain circumstances UDPGA may be the limiting factor in the in vivo glucuronidation of drugs by extrahepatic tissues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314965
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  • 8
    Electronic Resource
    Electronic Resource
    Stereoselective inhibition by chloroquine of histamine N-methyltransferase in the human liver and brain (1994)
    Springer
    European journal of clinical pharmacology 47 (1994), S. 345-349 
    Details
    ISSN: 1432-1041
    Keywords: Chloroquine ; Stereoselectivity ; Histamine ; methyltransferase ; liver ; brain ; man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract This study was designed to determine whether both enantiomers of chloroquine inhibit histamine N-methyltransferase. The mean estimates of IC50 for the d- and l-enantiomers of chloroquine were 4.9 and 17.8 μM (liver), respectively and 6.9 and 21.6 μM (brain), respectively. Ki estimates were significantly lower with d- than with l-chloroquine; hence, d-chloroquine interacts with the enzyme more effectively than l-chloroquine. If the adverse effects of chloroquine are due to the inhibition of histamine N-methyltransferase, therapy with the l-enantiomer might have lower toxicity. The residual activity of histamine N-methyltransferase should reflect both the degree of inhibition by chloroquine and the level of enzyme expression. The rate of histamine methylation was measured in 100 human liver samples and its range and fold of variation were 29% and threefold, respectively. Susceptibility to chloroquine should be greater in subjects with limited expression of histamine N-methyltransferase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00191166
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  • 9
    Electronic Resource
    Electronic Resource
    Human liver budesonide sulphotransferase is inhibited by testosterone and correlates with by testosterone sulphotransferase (1994)
    Springer
    European journal of clinical pharmacology 46 (1994), S. 49-54 
    Details
    ISSN: 1432-1041
    Keywords: Budesonide ; liver ; man ; sulphotransferase ; testosterone ; drug metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Budesonide, a corticosteroid used in the treatment of asthma and allergic reactions, is almost entirely cleared by metabolism in man. We describe the sulphation of budesonide in human liver and lung and provide evidences that the sulphation of budesonide is catalysed by testosterone sulphotransferase. A rapid and reproducible radiometric assay for budesonide sulphotransferase is described. Liver specimens were obtained from 35 men and 65 women and lung specimens from 2 women and 17 men. The average hepatic budesonide sulphation rate was significantly higher in men (41.1 pmol·min−1·ml−1) than women (28.2 pmol·min−1·mg−1). In the lung, the mean budesonide sulphation rate was 5.0 pmol·min−1·mg−1. Testosterone strongly inhibited the hepatic sulphation of budesonide, whereas p-nitrophenol and dopamine were poor inhibitors; the IC50 was 7.0 uM (testosterone), 320 uM (p-nitrophenol) and 510 uM (dopamine). The hepatic rates of testosterone, p-nitrophenol and dopamine sulphation were measured in the same samples assayed for budesonide sulphotransferase. There was a correlation between the hepatic rates of budesonide and testosterone sulphation (P〈0.001; r=0.810). The activity of testosterone sulphotransferase was significantly greater in men than women (22.0 vs. 17.2 pmol·min−1·mg−1), wheres those of dopamine and p-nitrophenol sulphotransferase were not sex dependent. The hepatic activity of budesonide sulphotransferase parallels that of testosterone suggesting that sulphation is an important reaction in the metabolism of budesonide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00195915
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  • 10
    Electronic Resource
    Electronic Resource
    Interethnic and interindividual variabilities of platelet sulfotransferases activity in Italians and Finns (1999)
    Springer
    European journal of clinical pharmacology 55 (1999), S. 691-695 
    Details
    ISSN: 1432-1041
    Keywords: Key words Sulfotransferase ; Variability ; Platelets
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: The aim of this investigation was to see whether there was interethnic variability in the platelet activities of catechol- and phenol sulfotransferases in Italians and Finns. Methods: The activities of catechol- and phenol sulfotransferases were measured in platelets obtained from 103 Italian and 74 Finnish individuals. Blood donors were obtained from healthy volunteers free from drugs and without apparent disease. The activities of catechol- and phenol sulfotransferases were measured with 60 μM dopamine and 4 μM 4-nitrophenol as substrates, respectively Results: The activity of catechol sulfotransferase was not gender dependent and the median estimates (pmol/min/mg) were 9.10 in Italians and 6.37 in Finns (P = 0.0018). The activity of phenol sulfotransferase activity was gender dependent in Finns but not in Italians. The median estimates (pmol/min/mg) were 3.81 in Finnish men and 1.18 in Finnish women (P = 0.0007). In Italian men and women, the median estimates (pmol/min/mg) of phenol sulfotransferase activity were 1.25 and 1.24, respectively (NS). Conclusion: This study shows that platelet catechol sulfotransferase activity is greater in Italians than Finns and that the activity of phenol sulfotransferase is gender regulated in Finns but not in Italians. Thus, interethnic differences exist in platelet sulfotransferases between Italians and Finns.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002280050695
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