Comparison of oseltamivir and oseltamivir carboxylate
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Comparison of Oseltamivir and Oseltamivir Carboxylate Concentrations in Venous Plasma, Venous Blood, and Capillary Blood in Healthy Volunteers Insti Instiaty, a,b Niklas Lindegardh, b,c† Podjanee Jittmala, b Warunee Hanpithakpong, b Daniel Blessborn, b,c Sasithon Pukrittayakamee, a Nicholas J. White, b,c Joel Tarning b,c Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand a ; Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand b ; Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom c Oseltamivir and oseltamivir carboxylate concentrations were measured in venous plasma, venous blood, and capillary blood taken simultaneously from 24 healthy volunteers. Median (range) venous-blood-to-plasma ratios were 1.42 (0.920 to 1.97) for oseltamivir and 0.673 (0.564 to 0.814) for oseltamivir carboxylate. Capillary blood/venous plasma ratios were 1.32 (0.737 to 3.16) for oseltamivir and 0.685 (0.502 to 1.34) for oseltamivir carboxylate. Oseltamivir concentrations in venous and capillary blood were similar. Oseltamivir carboxylate showed a time-dependent distribution between venous and cap- illary blood. O seltamivir (OS) is an orally bioavailable neuraminidase in- hibitor active against most strains of influenza viruses and licensed for the prevention and treatment of influenza infections (1). OS is rapidly absorbed after oral administration and is exten- sively converted by hepatic and plasma esterases to the bioactive metabolite oseltamivir carboxylate (OC) (2). OS and OC exhibit dose-linear pharmacokinetics (3), with peak plasma concentra- tions observed after approximately 1 and 4 h, respectively. OS has an elimination half-life of between 1 and 1.5 h, while the OC half-life is longer, ranging from 5 to 8 h (2, 3). The fraction of OC bound to plasma proteins is negligible (3%) compared to that of OS (approximately 42%) (4). OS and OC are usually quantified in venous plasma. Simpler sampling procedures using venous blood or capillary blood taken by finger prick would be advantageous for field studies, particu- larly in young children and infants. We report a comparison of the concentrations of OS and OC in samples of venous plasma, ve- nous blood, and capillary blood taken simultaneously from healthy volunteers. This study was nested into pharmacokinetic investigations in 24 healthy volunteers conducted at the Hospital for Tropical Dis- eases, Faculty of Tropical Medicine, Mahidol University, Bang- kok, Thailand, in 2010. It was approved by the ethics committee of the Faculty of Tropical Medicine. Venous blood samples (2.0 ml) taken through an indwelling catheter and capillary blood (50 l) taken by finger prick into a heparinized capillary tube were ob- tained from subjects at 1, 4, and 24 h after dosing with either 75 or 150 mg of oseltamivir (F. Hoffmann-La Roche Ltd., Basel, Swit- zerland) and transferred immediately into fluoride oxalate tubes. A 50-l venous blood aliquot was stored, and the remainder was centrifuged to obtain plasma. All samples were stored at 80°C until analysis. Plasma OS and OC concentrations were quantified using liquid chromatography coupled to tandem mass spectrom- etry (LC-MS/MS) (5). The lower limits of quantification (LLOQ) of OS and OC were set at 1 ng/ml and 10 ng/ml, respectively. The sample preparation and drug quantification in venous and capil- lary blood were identical to those described previously for plasma (5) except that the sample volume was set to 20 l and the injec- tion volume was set to 5 l. Comparisons were performed using the Wilcoxon matched- pairs signed-rank test for paired observations and the Friedman test for groups. Pairs were excluded from analysis if the analyte concentrations in one or both samples were below the LLOQ. Agreement between matrices and potential concentration-depen- dent differences were also assessed using Bland-Altman plots. The matrices were considered bioanalytically equivalent if 67% of data pairs were within 20% (6). Statistical analyses were per- formed using GraphPad Prism 5 (San Diego, CA). The concentration measurements of OS and OC are summa- rized in Table 1 and Fig. 1. All OS concentrations were below the LLOQ at 24 h after dosing. OS concentrations in venous plasma were significantly lower than those in venous blood (median [range], 27.5 [3.52 to 171] ng/ml versus 37.5 [5.18 to 250] ng/ml, respectively; n 96 pairs; P 0.0001). Bland-Altman plots showed that 14.6% (14/96) of data pairs were within the 20% limit of agreement. OS venous plasma concentrations were also significantly lower than those in capillary blood (25.4 [3.52 to 171] versus 31.1 [4.41 to 258] ng/ml, respectively; n 89 pairs; P 0.0001). A total of 33.7% (30/89) of data pairs were within the 20% limit of agreement. OS concentrations in venous blood were slightly higher than those in capillary blood (33.6 [5.18 to 250] versus 31.1 [4.41 to 258] ng/ml, respectively; n 89 pairs; P 0.03), although 70.8% (63/89) of data pairs were within the 20% limit of agreement. OS did not show time- Received 5 December 2012 Returned for modification 22 January 2013 Accepted 12 March 2013 Published ahead of print 18 March 2013 Address correspondence to Joel Tarning, [email protected]. † Deceased. Copyright © 2013, American Society for Microbiology. All Rights Reserved. doi:10.1128/AAC.02408-12 The authors have paid a fee to allow immediate free access to this article. 2858 aac.asm.org Antimicrobial Agents and Chemotherapy p. 2858 –2862 June 2013 Volume 57 Number 6 Downloaded from https://journals.asm.org/journal/aac on 23 November 2021 by 121.140.8.229.
Transcript of Comparison of oseltamivir and oseltamivir carboxylate
Comparison of Oseltamivir and Oseltamivir CarboxylateConcentrations in Venous Plasma, Venous Blood, and Capillary Bloodin Healthy Volunteers
Insti Instiaty,a,b Niklas Lindegardh,b,c† Podjanee Jittmala,b Warunee Hanpithakpong,b Daniel Blessborn,b,c Sasithon Pukrittayakamee,a
Nicholas J. White,b,c Joel Tarningb,c
Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailanda; Mahidol-Oxford Tropical Medicine Research Unit, Facultyof Tropical Medicine, Mahidol University, Bangkok, Thailandb; Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UnitedKingdomc
Oseltamivir and oseltamivir carboxylate concentrations were measured in venous plasma, venous blood, and capillaryblood taken simultaneously from 24 healthy volunteers. Median (range) venous-blood-to-plasma ratios were 1.42 (0.920 to1.97) for oseltamivir and 0.673 (0.564 to 0.814) for oseltamivir carboxylate. Capillary blood/venous plasma ratios were 1.32(0.737 to 3.16) for oseltamivir and 0.685 (0.502 to 1.34) for oseltamivir carboxylate. Oseltamivir concentrations in venousand capillary blood were similar. Oseltamivir carboxylate showed a time-dependent distribution between venous and cap-illary blood.
Oseltamivir (OS) is an orally bioavailable neuraminidase in-hibitor active against most strains of influenza viruses and
licensed for the prevention and treatment of influenza infections(1). OS is rapidly absorbed after oral administration and is exten-sively converted by hepatic and plasma esterases to the bioactivemetabolite oseltamivir carboxylate (OC) (2). OS and OC exhibitdose-linear pharmacokinetics (3), with peak plasma concentra-tions observed after approximately 1 and 4 h, respectively. OS hasan elimination half-life of between 1 and 1.5 h, while the OChalf-life is longer, ranging from 5 to 8 h (2, 3). The fraction of OCbound to plasma proteins is negligible (�3%) compared to that ofOS (approximately 42%) (4).
OS and OC are usually quantified in venous plasma. Simplersampling procedures using venous blood or capillary blood takenby finger prick would be advantageous for field studies, particu-larly in young children and infants. We report a comparison of theconcentrations of OS and OC in samples of venous plasma, ve-nous blood, and capillary blood taken simultaneously fromhealthy volunteers.
This study was nested into pharmacokinetic investigations in24 healthy volunteers conducted at the Hospital for Tropical Dis-eases, Faculty of Tropical Medicine, Mahidol University, Bang-kok, Thailand, in 2010. It was approved by the ethics committee ofthe Faculty of Tropical Medicine. Venous blood samples (2.0 ml)taken through an indwelling catheter and capillary blood (50 �l)taken by finger prick into a heparinized capillary tube were ob-tained from subjects at 1, 4, and 24 h after dosing with either 75 or150 mg of oseltamivir (F. Hoffmann-La Roche Ltd., Basel, Swit-zerland) and transferred immediately into fluoride oxalate tubes.A 50-�l venous blood aliquot was stored, and the remainder wascentrifuged to obtain plasma. All samples were stored at �80°Cuntil analysis. Plasma OS and OC concentrations were quantifiedusing liquid chromatography coupled to tandem mass spectrom-etry (LC-MS/MS) (5). The lower limits of quantification (LLOQ)of OS and OC were set at 1 ng/ml and 10 ng/ml, respectively. Thesample preparation and drug quantification in venous and capil-lary blood were identical to those described previously for plasma
(5) except that the sample volume was set to 20 �l and the injec-tion volume was set to 5 �l.
Comparisons were performed using the Wilcoxon matched-pairs signed-rank test for paired observations and the Friedmantest for groups. Pairs were excluded from analysis if the analyteconcentrations in one or both samples were below the LLOQ.Agreement between matrices and potential concentration-depen-dent differences were also assessed using Bland-Altman plots. Thematrices were considered bioanalytically equivalent if �67% ofdata pairs were within �20% (6). Statistical analyses were per-formed using GraphPad Prism 5 (San Diego, CA).
The concentration measurements of OS and OC are summa-rized in Table 1 and Fig. 1. All OS concentrations were below theLLOQ at 24 h after dosing. OS concentrations in venous plasmawere significantly lower than those in venous blood (median[range], 27.5 [3.52 to 171] ng/ml versus 37.5 [5.18 to 250] ng/ml,respectively; n � 96 pairs; P � 0.0001). Bland-Altman plotsshowed that 14.6% (14/96) of data pairs were within the �20%limit of agreement. OS venous plasma concentrations were alsosignificantly lower than those in capillary blood (25.4 [3.52 to 171]versus 31.1 [4.41 to 258] ng/ml, respectively; n � 89 pairs; P �0.0001). A total of 33.7% (30/89) of data pairs were withinthe �20% limit of agreement. OS concentrations in venousblood were slightly higher than those in capillary blood (33.6[5.18 to 250] versus 31.1 [4.41 to 258] ng/ml, respectively; n �89 pairs; P � 0.03), although 70.8% (63/89) of data pairs werewithin the �20% limit of agreement. OS did not show time-
Received 5 December 2012 Returned for modification 22 January 2013Accepted 12 March 2013
Published ahead of print 18 March 2013
Address correspondence to Joel Tarning, [email protected].
† Deceased.
Copyright © 2013, American Society for Microbiology. All Rights Reserved.
doi:10.1128/AAC.02408-12
The authors have paid a fee to allow immediate free access to this article.
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dependent or concentration-dependent differences betweenmatrices (Table 1).
OC concentrations in venous plasma were significantly higherthan those in venous blood (101 [16.0 to 888] versus 73.0 [10.4 to562] ng/ml, respectively; n � 137 pairs; P � 0.0001). The venous-blood-to-plasma ratios were similar at each time point (Table 1and Fig. 1). All data pairs were outside the �20% limit of agree-ment. OC concentrations in venous plasma were also significantlyhigher than those in capillary blood (92.9 [9.85 to 888] versus 78.2[10.3 to 556] ng/ml, respectively; n � 130 pairs; P � 0.0001). TheOC venous-plasma-to-capillary-blood ratios at 1, 4, and 24 h afterdosing were significantly different (P � 0.0001), indicating a time-dependent distribution between the two matrices (Table 1). Alldata pairs at 4 and 24 h after dosing were outside the limits of
agreement (Fig. 2). OC concentrations in venous blood were sig-nificantly lower than those in capillary blood (66.8 [10.4 to 562]versus 78.5 [10.3 to 556] ng/ml, respectively; n � 129 pairs; P �0.0014). This was because venous blood OC concentrations weresignificantly lower at 1 h (56.2 [13.6 to 335] versus 76.3 [16.4 to 329]ng/ml, respectively; P � 0.001), whereas the concentrations weresimilar at 4 h (209 [94.6 to 562] versus 216 [98.3 to 556] ng/ml,respectively; P � 0.070) and OC concentrations were slightly higherat 24 h (29.0 [10.4 to 92.5] versus 27.5 [10.3 to 92.1] ng/ml, respec-tively; P � 0.001) after dosing. The OC venous-blood-to-capillary-blood ratios at 1, 4, and 24 h after dosing were therefore significantlydifferent, indicating a time-dependent distribution between venousand capillary blood (P � 0.0001) (Table 1). A total of 100% and97.9% of data pairs were within the limits of agreement at 4 and 24 h
TABLE 1 Measured oseltamivir and oseltamivir carboxylate concentration ratios in venous plasma, venous blood, and capillary blood
Drug and ratio
Median (range) concn ratioP value by each statisticaltest
1 h after dosing 4 h after dosing 24 h after dosinga Pooled Wilcoxonb Friedmanc
OseltamivirVenous blood/venous plasma 1.40 (0.925–1.69) 1.44 (1.04–1.97) — 1.42 (0.920–1.97) 0.162Venous blood/capillary blood 1.04 (0.456–1.67) 1.06 (0.760–1.68) — 1.05 (0.460–1.68) 0.065Venous plasma/capillary blood 0.760 (0.320–1.36) 0.760 (0.450–1.21) — 0.759 (0.317–1.36) 0.693
Oseltamivir carboxylateVenous blood/venous plasma 0.683 (0.564–0.814) 0.664 (0.575–0.755) 0.685 (0.578–0.794) 0.673 (0.564–0.814) 0.139Venous blood/capillary blood 0.760 (0.520–1.02) 0.985 (0.901–1.10) 1.07 (0.847–1.29) 0.992 (0.525–1.20) �0.0001d
Venous plasma/capillary blood 1.14 (0.746–1.68) 1.47 (1.31–1.81) 1.55 (1.30–1.99) 1.46 (0.746–1.99) �0.0001e
a Oseltamivir concentrations measured in all matrices were all below the lower limit of quantification at 24 h after dosing (indicated by dashes).b Comparison of oseltamivir concentration ratios between matrices at 1 and 4 h after dosing.c Comparison of oseltamivir carboxylate concentration ratios between matrices at 1, 4, and 24 h after dosing.d By Dunn’s multiple-comparison analysis, the ratios for 1 versus 4 h, 1 versus 24 h, and 4 versus 24 h after dosing were all significantly different (P � 0.05).e By Dunn’s multiple-comparison analysis, the ratios for 1 versus 4 h and 1 versus 24 h were significantly different (P � 0.05), but the ratios at 4 versus 24 h were not significantlydifferent (P � 0.05).
FIG 1 Oseltamivir (OS) concentrations measured in venous plasma, venous blood, and capillary blood at 1 h (A) and 4 h (B) and oseltamivir carboxylate (OC)concentrations measured at 1 h (C), 4 h (D), and 24 h (E) after dosing. Error bars indicate median and interquartile ranges.
Oseltamivir Concentrations in Different Matrices
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after dosing, respectively (Fig. 3). There was no evidence of concen-tration-dependent distribution between the matrices.
Total intersubject variability (percent coefficient of variation[%CV]) measurements in venous plasma, venous blood, and cap-illary blood were 100%, 100%, and 107%, respectively, for OS and105%, 114%, and 97%, respectively, for OC. There was no corre-lation between the hematocrit values (median, 38.8%; range,31.6% to 46.8%) and OS blood/plasma ratios (P � 0.071), butthere was a very weak but significant negative correlation betweenhematocrits and the OC blood/plasma ratios (r2 � 0.069; P �0.002).
In this study, OS concentrations in venous blood were ap-proximately 42% higher than those in venous plasma whereasconcentrations of the active metabolite OC were 33% higher inplasma than in venous blood (Table 1). Similar results werefound comparing venous plasma and capillary blood concen-trations. Compound lipophilicity is an important determinantof distribution into cells (7). OC is a highly hydrophilic com-pound with a log P value of �2.1 (P is the octanol-water par-tition coefficient), which is much more polar than that for OS(log P value of 0.36) (8).
Blood taken from a finger prick is often referred to as cap-illary blood, although it is a mixture of arterial, venous, andcapillary blood and may also contain interstitial and intracel-
lular fluids (9). The greater pressure in arterioles and in thearterial limb of capillaries results in a greater ratio of arterial tovenous blood in finger prick blood (9). Significant arterio-venous concentration differences have been identified in anumber of drugs, and for these compounds, venous/capillarydifferences would also be expected (10). Venous/capillary dif-ferences in drug concentrations have been reported for piper-aquine (11), paracetamol (12), and artemisinin (13), while ve-nous/capillary concentrations of cyclosporine (9) andtobramycin (14) are reported to be similar.
In this study, there was a reasonable agreement between ve-nous blood and capillary blood for OS measurements (Table 1).However, a time-dependent distribution of OC between the twomatrices was evident. At 1 h after dosing, venous blood OC con-centrations were significantly lower than those in capillary blood,indicating incomplete equilibration. By 4 h, concentrations weresimilar (Fig. 3).
The overall variabilities of OS and OC were comparable in thedifferent matrices, even though venous and capillary blood sam-ple volumes (20 �l) for OS and OC measurements were lowerthan that used for quantification in venous plasma (50 �l). Sam-pling capillary blood taken by finger prick is simple and shouldfacilitate pharmacokinetic sampling in field studies, especially inpediatric studies. The next step will be to determine whether ac-
FIG 2 Bland-Altman plots of oseltamivir carboxylate (OC) concentrations in venous plasma and capillary blood at 1 h (A), 4 h (B), and 24 h (C) after dosing.Percent (%) difference on the y axis is the measured venous plasma OC concentration minus the capillary blood OC concentration divided by the mean of thecapillary blood and venous plasma concentrations. (D) Venous-plasma-to-capillary-blood oseltamivir carboxylate concentration ratios at 1 h, 4 h, and 24 h afterdosing, with error bars indicating median and interquartile ranges.
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curate and reliable assays can be performed on dried blood spotsamples taken onto filter paper.
In conclusion, measurements of OS and OC in venous plasmaand venous blood are not readily interchangeable, whereas venousblood and capillary blood sampling can be used interchangeablyprovided that the time-dependent distribution of OC is taken intoconsideration.
ACKNOWLEDGMENTS
This study was supported by the Southeast Asia Influenza Clinical Re-search Network with funding provided by the U.S. National Institute ofAllergy and Infectious Diseases. This study was part of the Mahidol-Ox-ford Tropical Medicine Research Unit funded by the Wellcome Trust ofGreat Britain.
The funders had no role in the design, conduct, analysis, or interpre-tation of this study.
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FIG 3 Bland-Altman plots of oseltamivir carboxylate (OC) concentrations in venous blood and capillary blood at 1 h (A), 4 h (B), and 24 h (C) after dosing.Percent (%) difference on the y axis is the measured venous blood OC concentration minus the capillary blood OC concentration divided by the mean of thevenous blood and capillary blood concentrations. (D) Venous-blood-to-capillary-blood oseltamivir carboxylate concentration ratios at 1 h, 4 h, and 24 h afterdosing, with error bars indicating median and interquartile ranges.
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