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To study the relation between drug release and the drug status within curcumin-loaded microsphere, SPG (shirasu porous glass) membrane emulsification was used to prepare the curcumin-PLGA (polylactic-co-glycolic acid) microspheres with three levels of drug loading respectively, and the in vitro release was studied with high-performance liquid chromatography (HPLC). The morphology of microspheres was observed with scanning electron microscopy (SEM), and the drug status was studied with X-ray diffraction (XRD), differential scanning calorimetry (DSC) and infrared analysis (IR). The drug loading of microspheres was (5.85 ± 0.21)%, (11.71 ± 0.39)%, (15.41 ± 0.40)%, respectively. No chemical connection was found between curcumin and PLGA. According to the results of XRD, curcumin dispersed in PLGA as amorphous form within the microspheres of the lowest drug loading, while (2.12 ± 0.64)% and (5.66 ± 0.07)% curcumin crystals was detected in the other two kinds of microspheres, respectively, indicating that the drug status was different within three kinds of microspheres. In the data analysis, we found that PLGA had a limited capacity of dissolving curcumin. When the drug loading exceeded the limit, the excess curcumin would exist in the form of crystals in microspheres independently. Meanwhile, this factor contributes to the difference in drug release behavior of the three groups of microspheres.
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OBJECTIVE:To establish a method for simultaneous determination of lysophosphatidyl choline(LPC)and lysophos-phatidyl ethanolamine(LPE)in Nimodipine fat emulsion. METHODS:HPLC was performed on the column of Lichrosher Diol with detector of evaporative light scattering detector with mobile phase A of heptane- isopropyl alcohol solution(43∶57,V/V),mobile phase B n-heptane-isopropyl alcohol-water(29.5∶59∶11.5,V/V/V)(gradient elution)at a flow rate of 1.5 ml/min,column tempera-ture was 40℃,and the injection volume was 20 μl. RESULTS:The linear range was 0.020 0-0.400 0 mg/ml for LPC(r=0.999 0)and 0.010 0-0.200 0 mg/ml for LPE(r=0.999 6),and the logarithm value of concentration and peak area showed good linear relationship;the limit of quantitation was 0.013 4 mg/ml for LPC and 0.013 0 mg/ml for LPE;the limit of detection was 0.007 8 mg/ml for LPC and 0.007 6 mg/ml for LPE;RSDs of precision,stability and reproducibility tests were lower than 2%;recoveries were 95.96%-100.63%(RSD=1.83%,n=9)and 99.22%-101.76%(RSD=0.80%,n=9). CONCLUSIONS:The method is simple,and can be used for the determination of related substance in Nimodipine fat emulsion.
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Objective To establish a high performance liquid chromatography method to detect the concentration of lamotrigine in blood dialysate and investigate in vitro recovery of lamotrigine and the factors.Select the microdialysis conditions that apply to the animal experiment and guide the stability study of in vivo recovery.Methods Positive dialysis and retrodialysis were used for the examination of lamotrigine in vitro recovery and the influencing factors such as flow rate, concentration, temperature and time.Filtered out the best conditions that apply to the in vivo experiment.Used the retrodialysis to determine the in vivo recovery and its stability.Results There was no significant difference between relative recovery and relative loss in the same flow rate.The concentration had no obvious effect on relative recovery.At the same condition,relative recovery decreased with the increase of the flow rate and increased with the temperature.The in vivo recovery had a good stability of 6.5 hours when the flow rate and stabilization time were set at 2μL/min and 1.5 h, respectivily.Conclusion Microdialysis technique can be used for the pharmacokinetic study of lamotrigine.Retrodialysis can be used for the determination of the lamotrigine in vivo recovery.