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Pharmacokinetic synergy from the taxane extract of Taxus chinensis improves the bioavailability of paclitaxel.

ABSTRACT

Background: Taxus chinensis (Pilger) Rehd is widely distributed in China and the northern hemisphere, and the most popular medicinal component isolated from Taxus chinensis is paclitaxel (PTX), which has now become the first-line chemotherapeutic drug for breast cancer and ovarian cancer. Oral administration of pure PTX as a potential anti-cancer agent is compromised by low bioavailability.

Hypothesis/purpose: In the clinical practice of traditional Chinese medicine, drug co-administration in the form of mixtures or formula could achieve pharmacokinetic/pharmacodynamic synergies. In this study, we aimed to investigate whether there exist any 'inherent' phytochemical synergy from Taxus chinensis extract that could improve PTX bioavailability.

Study design: Pharmacokinetic study of PTX after oral administration of Taxus chinensis extracts or single PTX was performed. In addition, comparative cytotoxic studies were carried out on the MCF-7 breast cancer cell lines.

Methods: The plasma concentrations of PTX were determined using a validated high performance chromatography tandem mass spectrometry method. The cytotoxicity was compared using the MTT assay.

Results: Oral administration of taxane fractions isolated from Taxus chinensis (containing 17.2% PTX) could achieve remarkably higher blood concentration and systemic exposure of PTX in rats, while the retention of PTX was significantly improved. Further tissue distribution analysis revealed that the penetration of PTX into major tissues was drastically increased compared with that of single PTX. In addition, in MCF-7 cells, the co-existing components in taxane mixtures could strengthen the inhibitory effects of PTX on tumor cell proliferation.

Conclusion: Together, these results support that administration of PTX in the form of taxane mixtures may become a novel approach to improve the poor bioavailability of PTX. Moreover, the inherent synergy from Taxus chinensis taxane extracts promises a novel strategy to strengthen PTX efficacy.

Keywords:

Taxus chinensis var. mairei

Paclitaxel

Bioavailability

Pharmacokinetic synergy

Tissue distribution

Cytotoxicity

Introduction

Taxus chinensis (Pilger) Rehd, also known as the Chinese yew, is a protected species in China and the extracts of many parts of the plant (e.g., roots, bark and leaves) have been commonly used in traditional Chinese medicine to treat cancer (Shi and Kiyota 2005; Tezuka et al. 2011; Qu and Chen 2014; Zheng et al. 2014). Modern pharmacology has led to the discovery of paclitaxel (PTX, Fig. 1A), a taxane-type diterpenoid, from the barks of Taxus chinensis, which is now applied intravenously (i.v.) as a broad-spectrum chemotherapeutic drug for breast cancer, ovarian cancer and non-small cell lung cancer (Dumontet and Jordan 2010). Ample studies have proven that PTX can induce cell cycle arrest and apoptosis via promoting microtubule polymerization and inhibiting microtubule depolymerization (Altmann and Gertsch 2007), and the unique structure and anticancer efficacy of PTX has drawn huge research interests worldwide (Watchueng et al. 2011).

The clinical application of commercial paclitaxel injection (Taxol[R]) is, however, hampered in part by anaphylactic reactions related to Cremophor EL, a surfactant used to improve the solubility of PTX (Nehate et al. 2014). Actually, the very poor solubility has become a major hurdle to the druggability of PTX. Against this disadvantage, oral administration of PTX has emerged as an attractive route (Jibodh et al. 2013), and, to this end, several novel drug delivery systems have been attempted for optimizing the anti-cancer benefit of PTX (Jain et al. 2012; Li et al. 2013; Lian et al. 2013; Hendrikx et al. 2014). However, it has been shown that the oral absorption and tissue distribution of PTX were largely restricted by active efflux and metabolic transformation (Hendrikx et al. 2013). To circumvent this major limitation, concomitant administration of transporter inhibitors (e.g., cyclosporine A, verapamil) with PTX has been proposed (Woo et al. 2003; Jibodh et al. 2013; Hendrikx et al. 2014), and it is noteworthy that several natural compounds (e.g., schizandrol B, ginsenoside Rg3) were found to effectively enhance the systemic exposure and even anti-tumor strength of PTX in animal models when orally co-administered Qin et al. 2010; Yang et al. 2012). These findings indicated that exploiting potential phytochemical combinations may become an invaluable approach for enhancing PTX exposure.

To explore a potential strategy to improve the production of PTX, we have previously prepared the taxane fractions from Taxus chinensis twigs and leaves leading to a 17.2% production of PTX, which was much higher than those traditionally produced from the barks of Taxus chinensis (Lv et al. 2014). We noted that, in the clinical practice of traditional Chinese medicine, drug co-administration in the form of mixtures or formula could achieve pharmacokinetic/pharmacodynamic synergies, a phenomenon also known as 'herbal compatibility' (Hao et al. 2014). Based on this rationale, we were particularly interested in whether the co-existing taxane components may influence the pharmacokinetics of PTX when they were administered per oral in the form of taxane mixtures. Herein, we report the interesting findings that, compared to giving PTX alone, oral administration of taxane combinations (containing 17.2% PTX) could lead to remarkably higher [C.sub.max] and AUC in rats. Moreover, the tissue distributions of PTX were also significantly increased. In MCF-7 breast cancer cell lines, we also observed that taxane mixtures could elicit more potent inhibitory effects on tumor cell proliferation in vitro than pure PTX. Together, our work suggested that administration of Taxus chinensis taxane extracts could become a promising avenue to improve the bioavailability of PTX, which might also contribute to better anti-tumor effects.

Materials and methods

Reagents and chemicals

Paclitaxel (HPLC purity > 98%; Lot # 100382-201102), 7-epipaditaxel (HPLC purity > 98%; Lot # 100927-201102), 7-epi-10-deacetyl paclitaxel (HPLC purity > 98%; Lot# 100925-200701), and diazepam (HPLC purity > 98%; Lot # 171225-200903) were supplied by the National Institute for the Control of Pharmaceutical and Biological Products (Beijing, China). 10-deacetylbaccatin III (HPLC purity > 98%; Lot # 120624) was purchased from Victory Biological Co., Ltd (Sichuan, China). The human breast cancer cell line MCF-7 was provided by Chinese Academy of Medical Science (Beijing, China). In cell experiments, all the biochemicals and 3(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) were obtained from Sigma (St. Louis, MO, USA). HPLC grade formic acid and methanol were purchased from ROE Scientific (Newark, DE, USA) and TEDIA (Fairfield, OH, USA), respectively. Distilled deionized water was prepared from a Milli-Q Pure Water System (Millipore, Bedford, MA, USA).

Plant material

The twigs and leaves of Taxus chinensis var. mairei (batch #20121025) were obtained from the Hongdoushan Pharmaceutical Co., Ltd. (Wuxi, China) and authenticated by Qinmei Zhou, senior pharmacist of Chinese Medicine in Nanjing University of Chinese Medicine Affiliated Hospital. A voucher specimen (20121025) is deposited at the Department of Pharmacy, Nanjing University of Chinese Medicine Affiliated Hospital, China.

Extraction and purification of taxane fractions

The preparation of taxane fractions from Taxus chinensis was performed according to our previously reported method (Lv et al. 2014). Briefly, the twigs and leaves (8 kg) were pulverized to powder and immersed in 70% EtOH (140 L), followed by 1-hour heated reflux for twice. The extracts were mixed and further concentrated under vacuum. Then, the crude product diluted with water was extracted three times with petroleum ether, and the lower layer was further extracted with C[H.sub.2][Cl.sub.2] (v:v = 1:1) for three times. The concentrated extractions (184 g) were then subject to silica gel column chromatography with gradient (v:v = 99:1, 98:2, 97:3; 96:4; 94:6; 92:8; 90:10; 85:15; 80:20; 70:30; 50:50; 0:100) C[H.sub.2][Cl.sub.2]/MeOH elution. The serial eluents were collected, concentrated and dissolved with methanol before HPLC analysis of potential taxane components. The taxane extracts were kept at 4[degrees]C before further pharmacological investigations.

Contents of major taxane components by HPLC-UV analysis

The contents of taxane compounds in the extraction were determined by a validated HPLC method. The analysis was performed on the Agilent 1100 HPLC equipped with a G1314A VWD detector. The separation was achieved on a C]g column (4.6 x 250 mm, 5 [micro]m; Agilent) with gradient elution (at the rate of 1.0 ml/min) of water (A) and acetonitrile (B) as follows: 0-16 min, 21-40% B; 16-50 min, 40-55% B; 50-54 min, 55-56%; 54-70 min, 56-65% B; 70-72 min, 65-21% B; 72-75 min, 21% B. The chromatographs were recorded under the wavelength of 227 nm.

LC-MS/MS method development

Chromatographic separation was performed on a Dionex UPLC system (Thermo Fisher, MA, USA). The separation was achieved on a Thermo Hypersil GOLD [C.sub.18] column (100.0 mm x 2.0 mm, 3 [micro]m) with a gradient elution (0.4 ml/min) of the mobile phase system consisting of 0.1 % formic acid (A) and methanol (B) as follows: 0-6.0 min, B% 20-85; 6.0-8.0 min, B% 85; 8.0-9.0 min, B% 85-20; 9.0-10.0 min, B% 20. The temperature of the column and auto-sampler was kept constant at 30[degrees]C and 10[degrees]C, respectively.

The HPLC system was interfaced to a TSQ quantum Access MAX triple quadruple mass spectrometer (Thermo Fisher, MA, USA) outfitted with an electrospray ionization (ESI) source. The mass spectrometer parameters were: probe voltage, 4.0 kV; source temperature, 200[degrees]C; capillary temperature, 350[degrees]C; sheath gas, 30 psi; auxiliary gas, 5 psi. The ions were detected (selective reaction monitoring) under positive mode with the optimized parameters: PTX, 876.25 [right arrow] 307.87, with collision energy (CE) at 31 eV; diazepam, 285.02 [right arrow] 154.06, with CE at 27 eV.

LC-MS/MS method validation

To determine the dynamic range of the method, five batches of calibration brain samples along with five blank samples were prepared and analyzed following the method mentioned above. The lower limit of quantification (LLOQ) was established as the lowest concentration of the calibration curve at which both the precision was within 20% and the accuracy was within 20% by means of the results from five replicates.

Intra- and inter-day variations were determined to validate the precision and accuracy of the assay. For the evaluation of intra-day variation, five replicates were determined at each concentration level, while five replicates at those three concentration levels determined over three consecutive days were analyzed to represent the inter-day variation. The precision of the method was expressed as RSD%.

The effects of rat plasma components on the ionization efficiency of PTX were evaluated by comparing the peak areas of the analytes spiked into blank extracted plasma with those of the counterparts prepared in methanol at three concentration levels. Extraction recovery tests were performed by making comparison between the peak areas of the sample prepared by plasma extraction and those of directly injected standards. The method validation for PTX quantification in mice tissues was performed in a similar way.

Plasma PTX dynamics

Male Sprague-Dawley rats (weighing 220 [+ or -] 20 g) were obtained from the Qinglongshan Experimental Animal Center (Nanjing, China) and kept in an environmentally-controlled breeding room for 1 week before the experimentation. Animal welfare and experimental procedures were strictly in accordance with the International Guide for the Care and Use of Laboratory Animals (Dawkins 2006) and approved by the Experimental Animal Ethics Committee of the Nanjing University of Chinese Medicine (Permit No. SYXK (Su)-2012-0047). The rats were fasted overnight (with free access to water) before the test. Based on our preliminary experiment results, the animals were orally given PTX (CMC-Na suspension, 70 mg/kg, n = 6) alone or taxane fractions (CMC-Na suspension, 407 mg/kg, n = 6), and 100 [micro]l of heparinized blood samples were collected at 0.25, 0.5, 0.75, 1, 2, 4, 6, 8, 12, 24, 48, 72 h from the ophthalmic veins and immediately centrifuged to obtain the plasma. The blood samples, spiked with diazepam (internal standard) solution (1 mg/ml), were extracted with tert-butyl methyl ether. The supernatant was then vaporized, reconstituted and transferred to LC-MS/MS analysis. The pharmacokinetic parameters were calculated by DAS software (Version 3.2.4, Shanghai, China).

Tissue distribution of PTX

ICR mice (male, weighing 22 [+ or -] 2 g) were obtained from the Qinglongshan Experimental Animal Center (Nanjing, China). The mice were gavaged with PTX (CMC-Na suspension, 98 mg/kg, n = 4) alone or taxane fractions (CMC-Na suspension, 570 mg/kg, n = 4). The mice were separately sacrificed at 0.5, 2, 4, 6 and 8 h, and the heart, liver, spleen, lung, kidney and brain were dissected and homogenized. The homogenates were extracted with tert-butyl methyl ether and processed for LC-MS/MS analysis.

Cell culture and MTT assay

MCF-7 cells were cultured in RPMI 1640 medium supplemented with 100 U/ml of penicillin G, streptomycin (Invitrogen, Carlsbad, CA) and 10% fetal bovine serum, and maintained at 37[degrees]C in a humidified incubator containing 5% C[O.sub.2]. The cells were used after reaching 80% confluence. PTX was firstly dissolved in DMSO to 10 mg/ml and further diluted with the culture medium. The taxane fractions were directly diluted with the culture medium. To examine the proliferation inhibitory effects, the cells were firstly exposed to different concentrations of PTX or taxane fractions prepared in culture medium for 24 h and 48 h, respectively. The MTT assay was then performed according to previous reports (Liu et al. 2013).

Statistical analysis

All data are presented as mean [+ or -] standard deviation (SD). Statistical differences between two groups were evaluated using the Student's t-test. For all of the analyses, a value of P < 0.05 was considered statistically significant.

Results and discussion

To gain knowledge of the major compositions, we firstly characterized the taxane compounds in the extracts using a validated HPLC method. With the chromatographic information from authentic taxane standards available (Fig. 1A-D), it was determined that the content of 10-deacetylbaccatin III (Peak 1), 7-epi-10-deacetyl paclitaxel (Peak 7), PTX (Peak 8) and 7-epi-paclitaxel (Peak 9) in the taxane extracts were 20.4%, 18.1%, 17.2% and 5.3%, respectively (Fig. 2). This result indicated that the taxane extracts contained large amounts (61.0%) of taxane compounds and provided the quantitative information for the administration of PTX in the form of taxane mixtures.

PTX is well known for its effects to inhibit cell proliferation and induce cell cycle arrest. Therefore, prior to the pharmacokinetic studies in vivo, we investigated the cytotoxicity of taxane extracts by the MTT assay. Here, MCF-7, a human breast cell line, was used, and pure PTX was employed as the positive control. As shown in Fig. 3A and B, the MTT assay indicated that both PTX and taxane mixtures could elicit potent inhibition on the proliferation of MCF-7 cells in a time- and concentration-dependent manner. The [IC.sub.50] of single PTX and taxane mixtures were 11.43 and 28.45 [micro]g/ml, respectively. Considering that the PTX concentration in the mixture was nearly 4.89 fig/ml (17.2% of taxane combinations), these results therefore suggested that the taxane mixtures could sensitize the MCF-7 cells to inhibitory effects of PTX. As some taxane-type compounds isolated from Taxus species could also exert anti-tumor effects (Shinozaki et al. 2002), the mechanism for this pharmacological synergy remains to be explored.

To investigate the possible changes in the pharmacokinetic behavior of PTX, a liquid-liquid extraction method was utilized for PTX extraction from plasma and tissue samples for its simplicity, high recovery and low endogenous interference compared with protein precipitation. Considering the extraction efficiency, tert-butyl methyl ether was finally chosen as the extraction solvent. In mass spectrometry detection, PTX and the internal standard were found to give higher responses in the positive mode. Addition of 0.1% formic acid to the mobile phase was found to further enhance the detection under the positive ionization mode. A gradient elution was further introduced, and, under the chromatographic conditions described above, the retention time for PTX and IS were 7.2 min and 6.8 min, respectively. No apparent interference was observed.

The developed method was then validated in terms of linearity, recovery, matrix effect, accuracy and precision. Good linearity was achieved over the concentration ranging from 0.01 to 52.1 [micro]g/ml of PTX ([r.sup.2] = 0.9981). The LLOQ of the method for PTX in rat plasma was 0.01 [micro]g/ml. The extraction recovery and matrix effect of the method was determined at low, medium and high concentrations and proved satisfactory (Table 1). Precision and accuracy of the method were validated at three concentrations as shown in Table 2. It was found that the intra- and inter-day variation and the value of accuracy were within the acceptable range. Together, these results suggested that the analytical method was specific, sensitive and reliable, which could be applied to quantitatively analyze PTX concentration in biological samples.

The developed method was successfully applied to analyze plasma PTX concentrations after oral administration of taxane mixtures (407 mg/kg) or single PTX (70 mg/kg) to rats. The mean plasma concentration-time profiles of PTX and the pharmacokinetic parameters are summarized in Fig. 4 and Table 3, respectively. As clearly shown in Fig. 4, pure PTX was poorly absorbed with low plasma concentration, but administration of taxane mixtures containing equivalent amount of PTX leads to a notable change in PTX plasma kinetics with nearly 10-fold increase in [C.sub.max] and a much delayed [T.sub.max], which indicated that the co-existing compounds could enhance the extent of oral absorption of PTX while lowering its rate.

In line with the increase in [C.sub.max], the [AUC.sub.0-48 h] and [AUC.sub.0-[infinity]] of PTX after taxane fraction administration were 13.55 [+ or -] 1.86 and 15.79 [+ or -] 2.75 [micro]g x h/L, respectively, which were 5.4- and 3.5-fold higher than those in rats receiving PTX alone (P < 0.01). In addition, PTX administered in the form of taxanes displayed much shorter MRT than PTX alone, and a possible explanation is that other taxane components may facilitate the transport of PTX out of the blood.

The remarkable effect of taxane mixtures on the plasma pharmacokinetics of PTX prompted us to investigate the potential influences on tissue distribution profile. In accordance, it was found that, after oral administration, PTX exhibited a wide distribution to mice tissues in the order of liver, lung, spleen, kidney, heart and brain. In comparison with single PTX administration, the distribution of PTX to lung (Fig. 5A), liver (Fig. 5B), kidney (Fig. 5C), heart (Fig. 5D), spleen (Fig. 5E) and brain (Fig. 5F) were drastically increased at several time points. Specifically, at the late phase, PTX concentration in the liver and lung were still very high in mice receiving taxane mixtures, which indicated that the co-existing components may enhance the retention of PTX to tissues. This might also partially explain the shorter MRT of PTX in blood after the administration of taxane fractions. In contrast to other tissues, the relatively low brain distribution of PTX did not exhibit a significant change after giving taxane fractions. Collectively, these tissue distribution results indicated that administration of taxane extracts might affect the distribution and retention of PTX in a tissue-dependent manner.

The oral availability of PTX is seriously hampered by drug efflux through P-glycoprotein (P-gp) and drug metabolism via cytochrome P450 (CYP) 3A (Hendrikx et al. 2014). Improvement of PTX bioavailability has therefore received intensive interests in recent years. Although several pharmaceutical delivery systems and chemical Pgp/CYP3A modulators have been reported, the potential synergistic effects from co-existing components in Taxus chinensis extract, which is the predominant form of medicinal use in traditional medicine, has not been explored before. In our work, the pharmacokinetic and tissue distribution study of PTX clearly demonstrated that administration of taxane fractions, prepared from the twigs and leaves of Taxus chinensis, could become a novel strategy to boost the bioavailability and tissue exposure of PTX in animals. Although the exact mechanism remains to be fully elucidated, this finding might be partially explained by the concept of 'herbal compatibility' where pharmacokinetic synergies are involved to enhance the bioavailability of natural compounds. Although PTX is a substrate of P-gp (Chae et al. 2013), the results from the cellular study on wild-type MCF-7 cells suggested that the synergy from the taxane fractions are possibly not related to P-gp, because wild-type MCF-7 cells do not express P-gp. Therefore, P-gp independent mechanisms have to be considered and the predominant mediator underlying the synergizing effect of taxane mixtures should be addressed in future studies. Actually, data from knockout mice also revealed that multidrug resistance protein 2 (MRP2) (Lagas et al. 2006) and CYP3A4 are also important determinants of PTX pharmacokinetics. Also, it has been shown that the extracts of Taxus species could inhibit the activity of CYP3A4 (Tezuka et al. 2011).

The significant increase of AUC, tissue distribution and in vitro tumor inhibitory effects of PTX by taxane components in our work suggested a possible improvement of anti-tumor efficacy by PTX. Although no obvious side effects from the animals in our experiment were observed, whether the increased systemic exposure could induce exacerbated systemic toxicity remains to be investigated. Notably, it has been acknowledged that there are increased risk of side effects and toxicity in clinical practice (e.g., central nervous system toxicity) when the oral bioavailability of PTX is substantially increased by concomitant inhibition of CYP3A and P-gp (van Waterschoot et al. 2009; Hendrikx et al. 2014). Therefore, the toxicity profile of Taxus chinensis taxane fractions after oral administration deserves in-depth evaluations in future studies.

Conclusion

In summary, in this work, we contributed to the interesting finding that oral administration of Taxus chinensis taxane extracts as a potential novel approach to improve the bioavailability of PTX. The pharmacokinetic results clearly demonstrated that the systemic exposure and tissue distribution of PTX could be markedly increased by the co-existing taxane components. Moreover, the in vitro inhibitory effects of PTX on tumor cell proliferation could also be strengthened. Together, these results indicated that oral administration of taxane fractions of Taxus chinensis may become a promising strategy to improve the systemic exposure of PTX.

Conflict of interest

The authors declare no conflicts of interest.

Acknowledgments

The work in this study is financially supported by the Priority Academic Program Development (PAPD, YSXK2010) of Jiangsu Higher Education Institutions to Nanjing University of Chinese Medicine.

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Zhihui Liu (a),(1), *, Xiao Zheng (a),(1), Jiajia Lv, (b),(1), Xiaowen Zhou (a), Qiong Wang (a), Xiaozhou Wen (a), Huan Liu (c), Jingyi Jiang (c), Liling Wang (c)

(a) Department of Pharmacy, Nanjing University of Chinese Medicine Affiliated Hospital, 155 HanZhong Road, Nanjing 210029, China

(b) School of Pharmaceutical Sciences, Zunyi Medical University, Zunyi 563003, China

(c) School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China

ARTICLE INFO

Article history:

Received 10 July 2014

Revised 13 February 2015

Accepted 19 March 2015

Abbreviations: PTX, paclitaxel; P-gp, P-glycoprotein; CYP, cytochrome P450; MRP2, multidrug resistance protein 2; [C.sub.max], peak plasma concentration; [T.sub.max], time to [C.sub.max]; MRT, mean retention time; [AUC.sub.0-t], area under the curve from 0 to time; [AUC.sub.0-[infinity]], area under the curve from 0 to infinity; MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazoliumbromide; LC-MS/MS, liquid chromatography tandem mass spectrometry; ESI, electrospray ionization; CE, collision energy.

* Corresponding author. Tel.: +86 25 86529291; fax: +86 25 86614204.

E-mail address: liuzhl008@126.com (Z. Liu).

(1) These authors contributed equally to this work.

http://dx.doi.org/10.1016/j.phymed.2015.03.011

Table 1
lntra- and inter-batch precision and accuracy of the LC-MS/MS
determination of paclitaxel in rat plasma (n = 5, mean  [+ or -]  S.D.).

                       Intra-day

Spiked concentration   Determined
[(micro]g/ml)          concentration          Precision   Accuracy
                       [(micro]g/ml)          RSD (%)     (%)

52.12                  46.24  [+ or -] 1.30   2.82        88.70
10.42                   9.27  [+ or -]  0.60  6.43        88.96
0.83                    0.82  [+ or -]  0.03  3.80        98.20

                       Inter-day

Spiked concentration   Determined              Precision   Accuracy
[(micro]g/ml)          concentration           RSD (%)     (%)
                       [(micro]g/ml)

52.12                  42.55  [+ or -] 1.84    4.33        87.39
10.42                   9.83  [+ or -]  0.95   9.71        94.29
0.83                    0.81  [+ or -]  0.02   2.50        97.12

Table 2 Recovery and matrix effect of the LC-MS/MS determination of
paclitaxel in rat plasma (n = 5, mean [+ or -] S.D.),

Nominal         Recovery (%)         Matrix effect (%)    RSD (%)
concentration
[micro]g/ml)

52.1            92.8 [+ or -] 7.2     96.7 [+ or -] 3.2    3.3
10.4            96.2 [+ or -] 7.8    101.9 [+ or -] 6.4    6.3
0.8             87.6 [+ or -] 14.8    95.5 [+ or -] 9.6   10.0

Table 3 The pharmacokinetic parameters of paclitaxel after oral
administration of pure paclitaxel or taxane mixtures
(n = 6, mean [+ or -] S.D.).

Parameters                                Pure paclitaxel

[C.sub.max] ([micro]g/L)                0.085 [+ or -] 0.008
[T.sub.max] (min)                       0.500 [+ or -] 0.000
[t.sub.1/2] (min)                      51.544 [+ or -] 11.687
[AUC.sub.0 - t] (ng min/ml)             2.523 [+ or -] 0.219
[AUC.sub.0 - [infinity]], (ng min/ml)   4.696 [+ or -] 1.204
[MRT.sub.0 - t](h)                     22.769 [+ or -] 0.329
[MRT.sub.0 - [infinity]](h)            78.170 [+ or -] 16.348

Parameters                                 Taxane fractions

[C.sub.max] ([micro]g/L)                0.714 [+ or -] 0.069 **
[T.sub.max] (min)                       2.333 [+ or -] 0.816 *
[t.sub.1/2] (min)                      17.221 [+ or -] 4.837 **
[AUC.sub.0 - t] (ng min/ml)             13.55 [+ or -] 1.859 **
[AUC.sub.0 - [infinity]], (ng min/ml)  15.792 [+ or -] 2.748 **
[MRT.sub.0 - t](h)                     16.069 [+ or -] 1.060
[MRT.sub.0 - [infinity]](h)            24.114 [+ or -] 4.325 *

* P < 0.05, vs pure paclitaxel.

** P< 0.01, vs pure paclitaxel.
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Author:Liu, Zhihui; Zheng, Xiao; Lv, Jiajia; Zhou, Xiaowen; Wang, Qiong; Wen, Xiaozhou; Liu, Huan; Jiang, J
Publication:Phytomedicine: International Journal of Phytotherapy & Phytopharmacology
Article Type:Report
Geographic Code:9CHIN
Date:May 15, 2015
Words:5091
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