Effect and evaluation of microenvironment pH on dissolution behavior of indomethacin solid dispersion

In this study, the effect of pH regulator meglumine(MEG)on the dissolution behavior of indomethacin(IND)amorphous solid dispersions was evaluated. The amorphous solid dispersion was prepared by hot-melt extrusion using IND and Kollidon^® VA64 at a weight ratio of 1∶4, and extrudates were characterized using differential scanning calorimetry(DSC)and X-ray powder diffraction(PXRD). The dissolution behaviors of solid dispersions with or without MEG were investigated in three kinds of pH media. The effect of infiltration rate of media, microenvironmental pH(pH_M)and recrystallization of drugs on drug dissolution were evaluated by designing the appropriate experiments. The results showed that the presence of MEG could accelerate the dissolution of IND from solid dispersions through providing an alkaline microenvironment, but in different dissolution media, the intensity and duration of alkaline microenvironment, recrystallization of local drug molecules and infiltration rate of media showed an obvious difference, and the above factors simultaneously affected the dissolution behavior of drugs from solid dispersions.