Study On Combretastatin A4 PLGA Nanoparticles

Objective:To prepare Combretastatin A4 sustained nanoparticles with Poly(lactic-co-glycolic acid)(PLGA)as the carrier material,to investigate the physicochemical properties and in-vitro release of nanoparticles.Method:First,an effective HPLC method was established to determine the content of CA4.Based on the method,the solubility of the drug in different pH phosphate buffer solutions,water and several organic solvents was measured.In addition,the drug/excipient compatibilities between CA4 and soybean lecithin S100 or PLGA were investigated under high temperature,high humidity and strong light.Second,CA4-PLGA nanoparticles were prepared by O/W emulsion solvent evaporation technique.Formulation factors,which may affect the appearance,particle size,encapsulation rate and drug loading of nanoparticles,were optimized by single factor screening to obtain the optimal formulation.Finally,the microscopic morphology was observed by fluoroscopic electron microscopy(TEM).The particle size was determined by Laser particle size analyzer.The encapsulation efficacy and drug loading were determined by HPLC.The physicochemical properties were characterized by X-ray diffraction(XRD),Differential scanning calorimetry(DSC)and Fourier Transform infrared spectroscopy(FT-IR).The in-vitro release study was performed by using a dialysis bag method.Results:CA4 showed a good linear relationship in the concentration range of 0.5 to 100 μg/mL(R2=0.9999).The quantitation limit and the detection limit were 0.1056 μg/mL and 0.0264μg/mL respectively.The precision and the stability of drug solution were good with less than 2%of RSD values.CA4 was practically insoluble in different pH phosphate buffer solutions and water.But it was soluble in several organic solvents,such as methyl alcohol,ethyl alcohol and acetone.No significant interactions were found between the drug and PLGA or soybean lecithin S100,while there was some reduction of CA4 under a strong light condition.The optimal procedure was shown as follows:the formulation composition of soybean lecithin S100 and PLGA were 0.375 mg and 1.25 mg respectively.The ratio of drug to carrier was 1 to 5.The organic phase volume was 0.25 ml,while the water volume was 5 ml.Average particle size of nanoparticles was 118.43±2.37 nm.The encapsulation efficiency and drug loading were 85.33±1.62%and 17.06±0.33%.XRD indicated that the decreased crystallinity of the drug in nanoparticles.DSC and FT-IR spectra showed that drug was encapsulated in the microspheres.The dissolution of CA4 significantly increased when it was incorporated in PLGA nanoparticles,and showed a sustained-release manner.Conclusions:The HPLC method for determining the content of CA4 is accurate and reliable.CA4 is poorly water-soluble,and the solubility is not affected by pH value.There were no obvious interactions between the drug and the excipients.CA4-PLGA nanoparticles prepared by O/W emulsion solvent evaporation technique showed suitable particle size,uniform dispersibility,high encapsulation efficacy,good process reproducibility and a sustained-release property.