Pharmacokinetic Study Of Polymeric Micelle Nanocarrier Material PEG-PLA

The treatment of cancer is a worldwide problem that needs to be solved urgently in the medical field.Using chemotherapy drugs to kill tumor tissue is still the main means for the treatment of cancer.However,while killing tumor tissues,chemotherapy drugs can also cause serious side effects.The nanoparticle drug delivery system is an new means for targeted drug delivery and reducing the side effects of chemotherapy drugs.With the advancement achieved in the design and synthesis of polymer nanocarriers,polymers have been widely used in nanoparticles.However,the absorption,distribution,metabolism,and elimination processes of polymers in biological systems have not been fully investigated.More and more studies have proved that many polymers that were generally considered to be inert are not inert in pharmacology.In order to develop nanoparticles with better pharmacokinetic behaviour and safety and to make the polymers to be better used in clinical applications,the establishment of quantitative method for polymers in biological samples and the fully understanding of pharmacokinetics of polymers are quite necessary.Polydisperse molecular weight of polymers makes it a great challenge for the quantification of polymers in vivo.In this study,poly?ethylene glycol?-block-poly?D,L lactic acid??PEG-PLA?,polymer nanomaterial of the marketed nanoparticle Genexol-PM,was used as a model nanomaterial.An analytical method based on liquid chromatography tandem mass spectrometry?LC-MS/MS?was developed for the quantification of PEG-PLA and pharmacokinetic study of PEG-PLA was carried out to reveal the in vivo fate of PEG-PLA.It provided references for the design of nanoparticles and in vivo fate studies of other polymers.?1?Characterization ofmolecularweightdistributionandmassspectrometry fragmentation behavior of PEG-PLAA new strategy based on quadrupole time-of-flight mass spectrometry?Q-TOF MS?for the characterization of molecular weight distribution of polymers was presented.By using the MS^ALLLL data acquisition mode of Q-TOF MS,low collision energy was applied in Q2 to ensure that the precursor ions of PEG-PLA were not broken,so that the intact precursor ions of PEG-PLA could pass through the TOF mass analyzer and the distribution information of the intact PEG-PLA was obtained.The molecular weight of PEG-PLA in this study is approximately with a median normal distribution of 4000 Da,which is consistent with the nominal molecular weight of PEG-PLA.The fragmentation behaviors of PEG-PLA in ion source and quadrupole of mass spectrometry were investigated separately by using MS^ALLLL technique.After that,the fragments classification was done by using SWATH technology.It was found that all of the precursor ions of PEG-PLA could produce PEG specific fragment ions like m/z 133,177and 221,PLA specific fragment ions like m/z 289,361,433,505,577 and PEG-PLA specific like m/z 333,405,477,549,621,693.This provides a prerequisite for the quantitative analysis of PEG-PLA.?2?Pharmacokinetic study of PEG-PLA in ratUsing PEG-PLA specific fragment ions as quantitative precursor ions,LC-MS/MS methods for the quantification of PEG-PLA in rat plasma were established based on in-source CID-MRM and MS^ALLLL respectively.The two methods were evaluated and compared,of which the results indicated that both of them had good accuracy and reproducibility and could be applied to the pharmacokinetic study of PEG-PLA.The results of pharmacokinetic study showed that PEG-PLA was slowly eliminated in rat plasma after a single intravenous injection of 37.5 mg/kg PEG-PLA.The t_1/2,C₀,C_max,AUC_0-t,AUC_0-?,Cl and V_z was 5.90±0.501 h,998±99.4?g/mL,979±89.5?g/mL,5998±620 h·?g/mL,6020±619 h·?g/mL,6.28±0.651 mL/h/kg and 53.6±8.50 mL/kg respectively.After 48 h of administration,the PEG-PLA in plasma was almost completely eliminated.?3?Biodistribution study of PEG-PLA in ratAn LC-MS/MS method for the determination of PEG-PLA in heart,liver,spleen,lung,kidney,stomach,large intestine,small intestine,brain,fat and muscle of rat was established.The distribution of PEG-PLA in heart,liver,spleen,lung,kidney,gastrointestinal tract,brain,fat and muscle of rat was investigated at 0.25 h,4 h and 36 h after intravenous injection of PEG-PLA.High concentration of PEG-PLA was found in spleen,liver and kidney due to the high perfusion rate and wide distribution of reticuloendothelial system?RES?in these organs.Whilst,low concentration of PEG-PLA was found in muscle and brain.?4?Metabolism and excretion of PEG-PLA in ratAn LC-MS/MS method for the determination of PEG-PLA in rat bile and urine was established.It was found that after intravenous injection of PEG-PLA,the unchanged PEG-PLA was not excreted in urine and only less than 0.2%of the administered PEG-PLA was excreted in bile.The results of the metabolism experiment showed that PEG-PLA was metabolized into PEG in vivo.PEG-PLA was mainly excreted as PEG in urine.After 96 h of intravenous administration,more than 80%of PEG-PLA could be excreted.?5?The inhibition effect of PEG-PLA on cytochrome P450 enzymesAn in vitro"cocktail"incubation system was established using the probe substrate method to determine the activities of seven major human cytochrome P450 enzymes including CYP 1A2,CYP 2B6,CYP 2C8,CYP 2C9,CYP 2C19,CYP 2D6 and CYP 3A4.Meanwhile,an LC-MS/MS method for the determination of the metabolites of the probe substrates corresponding to the seven P450 enzymes was established.The results of the inhibition experiments showed that PEG-PLA had no inhibition effect on human CYP1A2?CYP 2B6 and CYP 2C19 and weak inhibition effect on CYP 2C8?CYP 2C9?CYP2D6 and CYP 3A4.However,with the increasing of the concentration of PEG-PLA in the incubation system,PEG-PLA gradually showed inhibition effect on CYP 2C8,CYP 2C9,CYP 2D6,and CYP 3A4.Although the concentration at which PEG-PLA began to show inhibition effect was already very high,it is necessary to pay attention to the monitoring of PEG-PLA concentration in vivo to avoid influence of drug efficacy and side effects caused by PEG-PLA because the high clinical dose of PEG-PLA makes it possible to reach the inhibition concentration.