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| 2. |
- Lindegårdh, N, et al.
(författare)
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Piperaquine, new findings
- 2005
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Ingår i: International Congress for Tropical medicine and Malaria. - Marseille.
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Konferensbidrag (refereegranskat)
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| 3. |
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| 4. |
- Lindegårdh, Niklas, et al.
(författare)
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Development and validation of a bioanalytical method using automated solid-phase extraction and LC-UV for the simultaneous determination of lumefantrine and its desbutyl metabolite in plasma
- 2005
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Ingår i: Journal of Pharmaceutical and Biomedical Analysis. - : Elsevier BV. - 0731-7085 .- 1873-264X. ; 37:5, s. 1081-1088
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Tidskriftsartikel (refereegranskat)abstract
- A bioanalytical method for the determination of lumefantrine (LF) and its metabolite desbutyl-lumefantrine (DLF) in plasma by solid-phase extraction (SPE) and liquid chromatography has been developed. Plasma proteins were precipitated with acetonitrile: acetic acid (99:1, v/v) containing a DLF analogue internal standard before being loaded onto a octylsilica (3 M Empore) SPE column. Two different DLF analogues were evaluated as internal standards. The compounds were analysed by liquid chromatography UV detection on a SB-CN (250 mm x 4.6 mm) column with a mobile phase containing acetonitrile-sodium phosphate buffer pH (2.0; 0.1 M) (55:45, v/v) and sodium perchlorate 0.05 M. Different SPE columns were evaluated during method development to optimise reproducibility and recovery for LF, DLF and the two different DLF analogues. The within-day precisions for LF were 6.6 and 2.1% at 0.042 and 8.02 μ g/mL, respectively, and for DLF 4.5 and 1.5% at 0.039 and 0.777 μ g/mL, respectively. The between-day precisions for LF were 12.0 and 2.9% at 0.042 and 8.02 μ g/mL, respectively, while for DLF 0.7 and 1.2% at 0.039 and 0.777 μ g/mL, respectively. The limit of quantification was 0.024 and 0.021 μ g/mL for LF and DLF, respectively. Different amounts of lipids in plasma did not affect the absolute recovery of LF or DLF.
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| 5. |
- Singtoroj, T, et al.
(författare)
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A new approach to evaluate regression models during validation of bioanalytical assays
- 2006
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Ingår i: J Pharm Biomed Anal. - : Elsevier BV. ; 41:1, s. 219-227
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Tidskriftsartikel (refereegranskat)abstract
- The quality of bioanalytical data is highly dependent on using an appropriate regression model for calibration curves. Non-weighted linear regression has traditionally been used but is not necessarily the optimal model. Bioanalytical assays generally benefit from using either data transformation and/or weighting since variance normally increases with concentration. A data set with calibrators ranging from 9 to 10000 ng/mL was used to compare a new approach with the traditional approach for selecting an optimal regression model. The new approach used a combination of relative residuals at each calibration level together with precision and accuracy of independent quality control samples over 4 days to select and justify the best regression model. The results showed that log-log transformation without weighting was the simplest model to fit the calibration data and ensure good predictability for this data set.
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| 6. |
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| 7. |
- Tärning, Joel, 1977, et al.
(författare)
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Development and validation of an automated solid phase extraction and liquid chromatographic method for the determination of piperaquine in urine
- 2006
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Ingår i: J Pharm Biomed Anal. - : Elsevier BV. ; 41:1, s. 213-218
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Tidskriftsartikel (refereegranskat)abstract
- A sensitive and specific bioanalytical method for determination of piperaquine in urine by automated solid-phase extraction (SPE) and liquid chromatography (LC) has been developed and validated. Buffered urine samples (containing internal standard) were loaded onto mixed phase (cation-exchange and octylsilica) SPE columns using an ASPEC XL SPE robot. Chromatographic separation was achieved on a Chromolith Performance RP-18e (100 mm x 4.6 mm I.D.) LC column with phosphate buffer (pH 2.5; 0.1 mol/L)-acetonitrile (92:8, v/v). Piperaquine was analysed at a flow rate of 3 mL/min with UV detection at 347 nm. A linear regression model on log-log transformed data was used for quantification. Within-day precision for piperaquine was 1.3% at 5000 ng/mL and 6.6% at 50 ng/mL. Between-day precision for piperaquine was 3.7% at 5000 ng/mL and 7.2% at 50 ng/mL. Total-assay precision for piperaquine over 4 days using five replicates each day (n = 20) was 4.0%, 5.2% and 9.8% at 5000, 500 and 50 ng/mL, respectively. The lower limit of quantification (LLOQ) was set to 3 ng/mL using 1 mL of urine, which could be lowered to 0.33 ng/mL when using 9 mL of urine and an increased injection volume.
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| 8. |
- Tärning, Joel, 1977, et al.
(författare)
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Pitfalls in estimating piperaquine elimination
- 2005
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Ingår i: Antimicrob Agents Chemother. ; 49, s. 5127-8
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Tidskriftsartikel (refereegranskat)abstract
- By using a sensitive new assay, the terminal elimination half-life of the antimalarial piperaquine in a healthy volunteer was estimated to be 33 days, which is longer than estimated previously. This result illustrates the importance of extended sampling duration and sensitive assay methodologies in characterizing the disposition of slowly eliminated antimalarial drugs.
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