Preparation And Study On Tumor Targeting Of Paclitaxel Nanosuspensions By Folic Acid Modified

Paclitaxel(PTX),the first of a new class of microtubule stabilizing agents,has demonstrated significant antitumor activity in clinical trials against a broad range solid tumor,including refractory ovarian cancer,metastatic breast cancer,non-small-cell lung cancer,AIDS-related Kaposi's sarcoma.In recent years,a large number of domestic and foreign studies have shown that PTX has a strong anti-tumor effect,but because of its poor water solubility,low oral bioavailability,limits its clinical application and efficacy of the play.Because of its poor solubility in water,PTX is formulated in a 1:1 mixture of Cremophor EL(apolyethoxylated castor oil)and ethanol to create Taxol.Nanosuspensions have proved to be one of the most effective ways to deal with the dissolution problem of insoluble drugs with the advantage of very high drug payload and benefiting the biodistribution improvement of hydrophobic drugs.In this study,we using solvent precipitation in combination with high pressure homogeneous method preparation PTX nanosuspensions,improve the drug loading and increase the speed of drug absorption and absorption rate,enhance bioavailability.The main contents include the preparation,characterization release,MTT of nanosuspensions,in addition,the in vitro and in vivo study such as biodistribution and tumor inhibition experiments.Chol-PEG1000-FA conjugate was synthesized by an acidamide reaction between the carboxyl group of FA and the amino group of Chol-PEG1000-NH2 with pyridine as an activator and DCC as a coupled agent.It was reported that the ?-activated carboxyl group of FA is more accessible;therefore,it is possible that the acidamide reaction happened in y-carboxyl group then the ?-activated derivative was produced.PTX nanosuspensions were prepared by the solvent precipitation in combination with high pressure homogeneous method.Particle size and distribution of nanosuspensions for the evaluation of indicators,to optimize the formulation and its preparation process of the PTX nanosuspensions.Finally alone mPEG 1000-Chol and mPEG1000-Chol,Chol-PEG1000-FA mixture were used as a drug stabilizing agent.The PTX/mPEG1000-Chol nanosuspensionsdrug payload was(36.0±1.7)%(w/w).The nanosuspensions were spherical with the mean particle size of 203.96±2.63 nm and were monodisperse with PDI value of 0.188±0.01.Drug was amorphous form in the nanosuspensions.The PTX/Chol-PEG1000-FA nanosuspensions drug payload was(47.9 ± 1.2)%(w/w).The na nosuspensions were spherical with the mean particle size of 176.80±3.65 nm and were monodisperse with PDI value of 0.118±0.01.Drug was amorphous form in the nanosuspensions PTX nanosuspensions accumulative release reached 78.3%within 72 h.The MTT assay indicated that three kinds of PTX drugs display different orders of antitumor ability:Taxol>PTX/Chol-PEG1000-FA>PTX/mPEG1000-Chol in vitro.The IC50 value of the PTX solution was 0.7106,1.183 and 5.430 ?g/mL,approximately 1.6 times lower than those of the PTX/Chol-PEG1000-FA(1.183 ?g/mL).In order to investigate the biodistributin behaviors and targeting ability of on tumor-bearing mice,near-infrared fluorescent(NIFR)dye DIR was encapsulated into the PTX/Chol-PEG 1000-FA nanosuspensions for ex vivo optical imaging.The in vivo imaging study revealed that DIR loaded PTX/Chol-PEG1000-FA nanosuspensions distributed more in tumors in 4T1 tumor bearing mice than DIR loaded PTX/mPEG 1000-Chol nanosuspensions and solvent system of Taxol.At the dose of 30 mg free PTX per kg,PTX/Chol-PEG1000-FA showed significantly better efficacy than Taxol.The in vivo imaging study revealed that targeting the function of PTX/Chol-PEG1000-FA nanosuspensions better than PTX/mPEG1000-Chol nanosuspensions.These results suggest that PTX-loaded Chol-PEG1000-FA nanosuspensions can be considered as promising targeted delivery system for combination cancer chemotherapy to improve therapeutic efficacy and minimize adverse effects.