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- Svensson, Ulrika S H, et al.
(författare)
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High in situ rat intestinal permeability of artemisinin unaffected by multiple dosing and with no evidence of P-glycoprotein involvement
- 1999
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Ingår i: Drug Metabolism And Disposition. - 0090-9556 .- 1521-009X. ; 27:2, s. 227-232
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to investigate whether the decrease in artemisinin bioavailability after repeated oral dosing in humans can be a result of increased efflux of artemisinin by P-glycoprotein or decreased membrane transport at the intestinal barrier, The effective jejunal permeability (P-eff) of artemisinin was investigated using an in situ rat perfusion model. Fifty-four rats were randomized to one of three treatment arms: no pretreatment, pretreatment with artemisinin emulsion for 5 days (60 mg/kg/day, p.o.), or pretreatment with emulsion vehicle for 5 days, The rats within each treatment arm were randomized further to be jejunally perfused with either low (500 ng/ml) or high (5000 ng/ml) artemisinin concentration or low artemisinin concentration plus the P-glycoprotein inhibitor R,S-verapamil (400 mu g/ml). Perfusate samples were assayed for content of artemisinin, R,S-verapamil, and perfusion viability markers. Artemisinin P-eff was 1,44 +/- 0.38, 1.17 +/- 0.32, and 1.71 +/- 0.29 (.10(-4), cm/s) in rats receiving no pretreatment and perfused with low, high, or low artemisinin concentration plus verapamil, respectively. Multiple oral dosing of artemisinin did not affect the jejunal permeability of artemisinin, R,S-verapamil P-eff was similar in artemisinin-pretreated rats (1.09 +/- 0.54.10(-4), cm/s) and rats pretreated with only vehicle (1.07 +/- 0.37.10(-4), cm/s), The decrease in artemisinin bioavailability after multiple oral dosing in human is probably not a result of changes in P-glycoprotein expression or general intestinal transport. It seems more likely attributed to increased hepatocellular activity. Furthermore, artemisinin exhibits high jejunal permeability and is neither a substrate nor inducer of P-glycoprotein.
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| 2. |
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| 3. |
- Åkesson, Bengt, et al.
(författare)
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Major metabolic pathway for N-methyl-2-pyrrolidone in humans
- 1997
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Ingår i: Drug Metabolism and Disposition. - 1521-009X. ; 25:2, s. 267-269
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Tidskriftsartikel (refereegranskat)abstract
- The aim was to study the metabolic pathway for N-methyl-2-pyrrolidone (NMP) in humans. Three healthy male volunteers were administered 100 mg NMP orally. All urine was collected during nine consecutive days. The identification and quantification of the metabolites were performed by gas chromatography/mass spectrometry (GC/MS). NMP, 5-hydroxy-N-methyl-2-pyrrolidone (5-HNMP), N-methylsuccinimide (MSI), and 2-hydroxy-N-methylsuccinimide (2-HMSI) were found in urine. The mean excreted fractions for NMP, 5-HNMP, MSI, and 2-HMSI were 0.8%, 44%, 0.4%, and 20%, respectively. There was no conjugation with glucoronic acid or sulfate or either 5-HNMP or 2-HMSI. One-third of the orally dosed NMP was not recovered in urine as either NMP, 5-HNMP, MSI, or 2-HMSI. The half-lives for 5-HNMP, MSI, and 2-HMSI in urine were approximately 4, 8, and 17 hr, respectively.
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