| Based on the shortcomings of docetaxel in clinical use,a novel amphiphilic copolymer was used to modify docetaxel-loaded nanostructured lipid carrier(FA-DTX-NLC)to lead to a long blood circulating effect and targeting ability for the delivery of antitumor drug in cancer.The preparation,characteristics and in vivo study of FA-DTX-NLC were investigated as follow:1.Docetaxel loaded nanostructured lipid carrier modified by FA-PEG-PCHL was prepared by high pressure homogenizing method.Transmission electron microscopy was employed to study the morphology,and spherical or ellipsoid-shaped particles were found,with diameter about 130 nm.The content,Zeta potential and entrapment efficiency were investigated as well.The in vitro release study indicated that docetaxel in FA-DTX-NLC released slower than injection and NLC.2.The degradation kinetics of docetaxel in FA-DTX-NLC was investigated by high performance liquid chromatography.Influence factors of degradation kinetics,pH(1.5,3.0,5.0,7.4 and 9.0),temperature(25,37,60 and 80?)and light were studied.The rate obtained by measuring the remaining intact docetaxel was shown to follow first-order kinetics.The activation energies(Ea)for degradation were 62.05,84.0,91.4,86.0 and 68.28 kJ-mol"1 at pH 1.5,3.0,5.0,7.4 and 9.0,respectively.FA-DTX-NLC was stable in neutral and weak acidic conditions,but decomposed to form degradation products under strong acid and basic condition or at high temperature.3.To investigate the in vivo characteristics of modified docetaxel-loaded nanostructured lipid carrierznvivo,a liquid chromatography-mass spectrometry method was developed and validated for the determination of docetaxel in rat plasma.The plasma samples were extracted by liquid-liquid extraction method with ether and separated on a C18 column(150 X 4.6 mm,5 m)using a mobile phase consisting of methanol-0.01%formic acid water(82:18,v/v).The standard curves were linear over the ranges of 10?4000 ng-mL-1 for plasma.The validated method was successfully applied to the pharmacokinetic study of docetaxel in rat plasma after an intravenous administration of docetaxel injection(DTX injection),docetaxel-loaded nanostructured lipid carrier(DTX-NLC)and FA-PEG-PCHL-modified docetaxel-loaded nanostructured lipid carrier(FA-DTX-NLC),respectively.The pharmacokinetic parameters of docetaxel of three formulations were as follows:JUC0-24 were 2544 ± 283,6688 ± 625,1.065 × 104 ± 0.210 × 104 ?g·h·mL-1;J(/0A0-??were 2568 ± 267,6773 ± 640,1.071 × 104± 0.210 × 104?g·h·mL-1;MRT0-24 were 0.65 ± 0.09,0.72 ± 0.10,1.84 ± 0.39 h;MRT0-?,were 0.72 ± 0.11,0.92 ± 0.07,2.03 ? 0.59 h;CLz,were 3.932 ± 0.432,1.489 ± 0.160,0.969 ± 0.222 L·kg-1-h-1,respectively.The results indicated that the FA-DTX-NLC led to significant differences in pharmacokinetic profile and tissue distribution.Nanostructured lipid carrier modified by FA-PEG-PCHL could be one of the promising suspensions for the delivery of docetaxel in cancer.A rapid,simple and sensitive ultra fast liquid chromatography-tandem mass spectrometry(UFLC-MS/MS)method coupled with one-step protein precipitation procedure has been developed and validated for the pharmacokinetic study of docetaxel in rat plasma.The standard curve was linear over the range of 5?5000 ng-mL-1.With the doses of 2.5,5.0 and 10 mg·kg-1 pharmacokinetic parameters were obtained.Dose-dependent linear relationships of AUC0-t,and Cmmax.for docetaxel was found in the range of 2.5 to 10 mg-kg-1 after intravenous administration to rats.Gender difference investigation was carried out through all the study and there were significant differences(p<0.05)in main pharmacokinetic parameters AUC.4.The tissue distribution of docetaxel in rats after intravenous administration of FA-DTX-NLC at does of 5 mg-kg-1 was investigated.10 min after drug administration,docetaxel was broadly distributed in all the tissues examined.Tissue-specific distributions were observed,the liver,lung,pancreas,intestine,spleen,kidney,and heart manifested as the dominant organs with high tissue concentrations which might be responsible for large volume of blood flow.The presence of drug in the brain indicated that docetaxel could penetrate the blood brain barrier.Higher drug concentrations were found in most organs of female rats might due to gender differences in drug metabolism.The excretion of docetaxel from rats after intravenous administration of FA-DTX-NLC at does of 5 mg-kg-1 was investigated.The cumulative amount for docetaxel were 18.42 ±4.10 ?g for male rats and 13.24 ± 2.95 ?g for female rats in urine within 72 h after administration,which amounted to 1.84%and 1.32%of the given dosage,respectively.In feces,the cumulative amount were 62.17 ± 23.20 ?g for male rats and 50.36 ± 18.57 ?g for female rats,which amounted to 6.21%and 2.32%of the given dosage,respectively,indicating excretion in feces is the main excretion form of docetaxel.The excretion of docetaxel from bile was approximately equal to that from urine,with the cumulative amount of 19.44 ± 2.86 ?g for male rats and 14.19 ± 2.03 ?g for female rats 0?24 h after dosing.5.A sensitive and selective liquid chromatography-mass spectrometry(LC-MS)method was developed and validated for the determination of docetaxel in S-180 mice tissue to evaluate the tissue distribution of modified docetaxel nanostructured lipid carrier(FA-DTX-NLC).S-180 mouse of 54 were randomly divided into three groups for intravenous administration of docetaxel injection,DTX-NLC and FA-DTX-NLC,respectively.Docetaxel was determined by LC-MS in selected ion monitoring mode.The tissue distribution study on tumor bearing mouse showed FA-DTX-NLC significantly altered the docetaxel distribution behavior compared with docetaxel injection and DTX-NLC.In folate receptor rich tissue such as tumor,concentration of docetaxel in FA-DTX-NLC was much higher than docetaxel injection and DTX-NLC(p<0.05),which suggested FA-DTX-NLC held a better anti-tumor effect.S-180 mouse tumor model was used for the anti-tumor effect study of FA-DTX-NLC.The relative tumor inhibition rate was 69.6%,which was significantly higher than that of docetaxel injection and DTX-NLC. |
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