Studies On Oral Bioavailability Enhancement Of Imatinib Using Galactosylated Nanoparticles

Chronic myelogenous leukemia?CML?is a malignant tumor affecting the blood and bone marrow,characterized by the accumulation of immature white blood cells in the bone marrow to inhibit normal hematopoiesis.And can spread through the blood throughout the body,resulting in anemia,prone to bleeding,infection and organ infiltration.CML is clinically divided into chronic phase,acute phase and accelerated phase.Chronic phase is mild,and failure to continue treatment in chronic phsae can lead to a more dangerous acute and accelerated phase,during which leukemia cells cause abnormal gene changes,faster proliferation,resistance to apoptosis,and,if left untreated,eventual death.At present,the pathogenesis of CML is still unclear,but more than 95%of patients with CML have been found to have Philadelphia chromosome?Ph?,so it is believed that the heterotopic formation of BCR-ABL fusion protein on chromosomes 9 and 22 is closely related to the disease.Imatinib?IMT?is a tyrosine kinase inhibitor,which mainly exerts the effect of molecular targeted therapy on CML by inhibiting the BCR-ABL fusion protein.The BCR-ABL fusion protein directs the encoding of tyrosine kinases,and CML treatment can begin at this site.With the development of molecular biology,tyrosine kinase inhibitor?TKI?,a small molecule substance,has been developed for the targeted therapy of CML.Imatinib?IMT?is a tyrosine kinase inhibitor,which mainly exerts the effect of molecular targeted therapy on CML by inhibiting the BCR-ABL fusion protein.Although IMT has certain clinical value for the treatment of chronic myelogenous leukemia,tyrosine kinase inhibitors have many adverse reactions to the treatment of CML.Mild adverse reactions include edema,fatigue,itching of the skin,and more severe reactions relate to gastrointestinal tract,muscle soreness and rashes,etc.,which have seriously affected the quality of life of patients.In order to alleviate the adverse reactions of imatinib in CML patients,a new method was proposed in this thesis.Synthetic N-oleoyl galactose and PLGA were used as carrier materials to construct ligand-mediated active targeting system for oral delivery of IMT.By virtue of galactosylated nanoparticles?GNPs?,less drug release and degradation in the gastrointestinal tract was achieved,thus promoting oral absorption of IMT and increasing the oral bioavailability thereof,as well as reducing adverse reactions to the body.The main research methods of this paper are as follows:The synthesis of N-oleoyl-D-galactosamine.It is mainly carried out by acylation reaction to complete the conjugation of N-oleoyl to galactosamine.The synthesized product was identified by H¹NMR.we prepared and characterized IMT-loaded galactosylated nanoparticles?IMT-GNPs?.IMT-GNPs are prepared by a solvent diffusion technology.The particle size and polydispersity index?PDI?of nanoparticles were used as indices to investigate the effects of formulation variables on the nanoparticles in order to determine the optimal formulation.IMT-GNPs were characterized by particle size,zeta potential,micromorphology under transmission electron microscopy?TEM?,entrapment efficiency,and in vitro release.the bioavailability of IMT-GNPs was studied in vivo using SD rats as experimental animals,three preparations of IMT-GNPs,IMT suspension and IMT-NPs were administered by oral gavage.At the predetermined interval,0.25 m L of blood was withdrawn from the tail vein of rats and immediately transferred to heparinized tubes.Blood samples were then centrifuged at 4,500 rpm for 5 minutes to collect plasma.Plasma samples were processed by organic solvent precipitation method.The supernatant was collected and reconstituted for HPLC assay.The drug concentration in plasma samples was analyzed by HPLC established by us.To study the oral absorption mechanism of IMT-GNPs.A series of cell experiments and ex vivo imaging on absorptive epithelia following administration were performed.Cell uptake,internalization,transport mechanism,and intestinal permeability were investigated.The research results of this paper are as follows:N-oleoyl-D-galactosamine has the amphiphilic nature that can serve as a surfactant and insert into PLGA nanoparticles for functionalization.The experimental results of IMT-loaded galactosylated nanoparticles?IMT-GNPs?show that the particle size of IMT-GNPs is 122 nm around with a PDI of 0.201 and a zeta potential of-23.4 mv.The microscopic morphology of IMT-GNPs observed by TEM is spherical and uniform in distribution.The entrapment efficiency was determined using the centrifugal ultrafiltration technology by separating free drug from nanoparticles.The drug concentration in the subsequent filtrate was quantified by high performance liquid chromatography?HPLC?.The experimental results showed that the entrapment efficiency of IMT-GNPs was 93.06±0.66%.The dialysis bag method was utilized to study the in vitro release of IMT from IMT-GNPs with IMT solution and IMT suspensions as reference preparations.It was shown that IMT-GNPs had less release in different media relative to IMT solution and IMT suspension.The results of the bioavailability of IMT-GNPs showed that the relative bioavailability of IMT-NPs and IMT-GNPs were 115.20±15.29%and 152.25±22.59%,respectively.The area under the plasma concentration-time curve(AUC_0-t)of IMT suspensions,IMT-NPs and IMT-GNPs were 25.529±4.143?g/m L·h,29.408±3.903?g/m L·h and 38.868±5.767?g/m L·h,respectively.IMT-GNPs have the potential of promoting oral absorption of IMT and enhancing its bioavailability.In comparison with IMT-NPs,IMT-GNPs demonstrated higher cell intake and intestinal epithelial affinity and permeability,which is associated with particular trans-membrane transport of IMT-GNPs through multiple transport mechanisms.Taken together,we found that GNPs have excellent oral drug delivery potential that not only can reduce drug exposure to gastrointestinal tract,thereby reducing IMT degradation in the gastrointestinal tract and related adverse reactions caused by drug exposure,but also improve the oral absorption of IMT by way of the intestinal epithelial galactose transporter.This study systematically studies the oral absorption characteristics of IMT in different formulation modalities,which shed a light on oral drug delivery systems and the development of innovative IMT preparations.Meanwhile,this study also contributes great scientific significance to the clinical application of IMT.