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- Simonsson, Ulrika S H, et al.
(författare)
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Artemisinin autoinduction is caused by involvement of cytochrome P450 2B6 but not 2C9.
- 2003
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Ingår i: Clinical pharmacology and therapeutics. - 0009-9236 .- 1532-6535. ; 74:1, s. 32-43
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Tidskriftsartikel (refereegranskat)abstract
- Our goal was to investigate whether artemisinin autoinduction is caused by an increase in cytochrome P450 (CYP) 2B6 or CYP2C9 activities, we evaluated the effects of multiple-dose artemisinin administration on S-mephenytoin N-demethylation in healthy subjects.
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- Svensson, Ulrika S H, et al.
(författare)
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Artemisinin induces omeprazole metabolism in human beings
- 1998
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Ingår i: Clinical Pharmacology and Therapeutics. - 0009-9236 .- 1532-6535. ; 64, s. 160-
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Tidskriftsartikel (refereegranskat)abstract
- Objective: This study investigated whether time-dependent artemisinin pharmacokinetics correlated to CYP3A4 or CYP2C19 activity in vivo. Methods: Artemisinin (two oral doses per day of 250 mg) was given to nine healthy Vietnamese subjects for 7 days (day 1 to day 7), Single 20 mg doses of omeprazole were given orally on day -7, day 1, and day 7, Single doses of artemisinin and omeprazole were given in combination on day 14 after a 6-day washout period. The pharmacokinetics of artemisinin, omeprazole, hydroxyomeprazole, and omeprazole sulfone were evaluated on days -7, 1, 7, and 14, On the same days urine was collected for the determination of 6 beta-hydroxycortisol and cortisol excretion. Results: Areas under plasma concentration-time curves (AUC) for artemisinin and omeprazole decreased on day 7 to 20% (95% confidence intervals, 13%, 28%) and 35% (25%, 46%), respectively, compared with values on day 1, AUC ratios for hydroxyomeprazole/omeprazole increased 2.2-fold (1,7, 2.7) on day 7 compared with values on day 1, Al values were normalized at day 14, There were no significant changes in the omeprazole sulfone/omeprazole ratio or in the 6 beta-hydroxycortisol/cortisol ratio between the study days. In one subject found to have poor CYP2C19 metabolization, the elimination of omeprazole increased after artemisinin exposure, with no change in the hydroxyomeprazole/omeprazole AUC ratio. Conclusion: Artemisinin did not alter CYP3A4 activity, whereas an increase in CYP2C19 activity was observed. The increased elimination of omeprazole in both poor and extensive CYP2C19 metabolizers suggests artemisinin induces both CYP2C19 and another enzyme.
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- Wadelius, Mia, et al.
(författare)
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Induction of CYP2D6 in pregnancy
- 1997
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Ingår i: Clinical Pharmacology and Therapeutics. - 0009-9236 .- 1532-6535. ; 62:4, s. 400-7
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Tidskriftsartikel (refereegranskat)abstract
- Expression of the drug-metabolizing enzyme cytochrome P4502D6 (CYP2D6) is predominantly under genetic control, and enzyme-inducing drugs have little influence on its activity. We studied the activity of CYP2D6 during pregnancy. One hundred forty pregnant women were genotyped for CYP2D6. Seventeen of them (four poor metabolizers, seven heterozygous extensive metabolizers, and six extensive metabolizers) were phenotyped with dextromethorphan in late pregnancy and 7 to 11 weeks after parturition. During pregnancy the dextromethorphan/dextrorphan metabolic ratio was significantly reduced (p = 0.0015) among homozygous and heterozygous extensive metabolizers, indicating increased CYP2D6 activity. In contrast, poor metabolizers showed an increased metabolic ratio during pregnancy. These results are consistent with previous findings of a marked increase in metabolism of the CYP2D6 substrate metoprolol during pregnancy. Both studies indicate an increase in CYP2D6 activity during pregnancy, which may be caused by an induction of the CYP2D6 enzyme.
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- Abrantes, João A., et al.
(författare)
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Elucidation of Factor VIII Activity Pharmacokinetics : A Pooled Population Analysis in Patients With Hemophilia A Treated With Moroctocog Alfa
- 2017
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Ingår i: Clinical Pharmacology and Therapeutics. - : Wiley. - 0009-9236 .- 1532-6535. ; 102:6, s. 977-988
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated the disposition of coagulation factor VIII activity in 754 patients with moderate to severe hemophilia A following the administration of moroctocog alfa, a B-domain deleted recombinant factor VIII. Data analyzed included patients aged 1 day to 73 years enrolled in 13 studies conducted over a period of 20 years in 25 countries. A two-compartment population pharmacokinetic model with a baseline model described the pooled data well. Body size, age, inhibitors, race, and analytical assay were identified as significant predictors of factor VIII disposition. In addition, simulations of prophylactic dosing schedules in several pediatric cohorts showed large variability and suggest that younger patients would require higher weight-adjusted doses than adolescents to achieve target factor VIII trough activity when receiving every other day or twice weekly dosing.
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- Alfirevic, A., et al.
(författare)
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Phenotype Standardization for Statin-Induced Myotoxicity
- 2014
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Ingår i: Clinical Pharmacology and Therapeutics. - : Springer Science and Business Media LLC. - 0009-9236 .- 1532-6535. ; 96:4, s. 470-476
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Forskningsöversikt (refereegranskat)abstract
- Statins are widely used lipid-lowering drugs that are effective in reducing cardiovascular disease risk. Although they are generally well tolerated, they can cause muscle toxicity, which can lead to severe rhabdomyolysis. Research in this area has been hampered to some extent by the lack of standardized nomenclature and phenotypic definitions. We have used numerical and descriptive classifications and developed an algorithm to define statin-related myotoxicity phenotypes, including myalgia, myopathy, rhabdomyolysis, and necrotizing autoimmune myopathy.
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- Amidon, K. S., et al.
(författare)
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Bioequivalence of Oral Products and the Biopharmaceutics Classification System : Science, Regulation, and Public Policy
- 2011
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Ingår i: Clinical Pharmacology and Therapeutics. - : Springer Science and Business Media LLC. - 0009-9236 .- 1532-6535. ; 90:3, s. 467-470
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Tidskriftsartikel (refereegranskat)abstract
- The demonstration of bioequivalence (BE) is an essential requirement for ensuring that patients receive a product that performs as indicated by the label. The BE standard for a particular product is set by its innovator, and this standard must subsequently be matched by generic drug products. The Biopharmaceutics Classification System (BCS) sets a scientific basis for an improved BE standard for immediate-release solid oral dosage forms. In this paper, we discuss BE and the BCS, as well as the issues that are currently relevant to BE as a pharmaceutical product standard.
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- Avery, P. J., et al.
(författare)
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A Proposal for an Individualized Pharmacogenetics-Based Warfarin Initiation Dose Regimen for Patients Commencing Anticoagulation Therapy
- 2011
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Ingår i: Clinical Pharmacology and Therapeutics. - : Springer Science and Business Media LLC. - 0009-9236 .- 1532-6535. ; 90:5, s. 701-706
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Tidskriftsartikel (refereegranskat)abstract
- A significant proportion of the interindividual variability in warfarin dose requirements can be explained on the basis of CYP2C9 and VKORC1 genotypes. We report the development of a novel pharmacogenetics-based 3-day warfarin initiation dose (ID) algorithm based on the International Warfarin Pharmacogenetics Consortium (IWPC) maintenance dose algorithm and the CYP2C9 genotype-based variance in warfarin half-life. The predictive value of the pharmacogenetics-based ID was assessed in a large cohort of 671 newly diagnosed patients with thromboembolic disorders who were about to commence anticoagulation therapy in accordance with standard induction regimens. In patients with mean international normalized ratio (INR)(days 4-7)>4.0 (n = 63) after warfarin initiation, the pharmacogenetics-based ID algorithm predicted a markedly lower dose requirement (median reduction = 4.2 mg), whereas in those with mean INR(days 4-7) < 2.0 (n = 145), the predicted dose requirement was very similar to that in the standard regimen. The use of a pharmacogenetics-based ID may avoid overshooting of INR in warfarin-sensitive patients without unduly affecting the time taken to reach target range in the majority of patients.
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