The present study evaluates the effect of several pharmaceutical plasticizers on the thermo-physical and physicochemical properties of partially hydrolyzed poly(vinyl alcohol) (PVA) used in fusion-based pharmaceutical formulation processes. Specifically, the effect of mannitol (MAN), sorbitol (SOR), sucrose (SUC), anhydrous citric acid (CA), triethyl citrate (TEC) and low-molecular weight polyethylene glycol (PEG400) on PVA's melting properties, physical state and thermal degradation was evaluated via differential scanning calorimetry (DSC), powder X-ray diffractometry (pXRD) and thermo-gravimetric analysis (TGA). Results showed that the use of MAN, SOR, SUC and PEG400 led to the reduction of PVA's melting onset temperature, while MAN, SUC, CA and SOR were amorphously dispersed within PVA's matrix, and the addition of SUC and CA resulted in significant reduction of PVA's crystallinity. TGA results showed the formation of thermally highly unstable PVA mixtures in the cases of CA and TEC (degradation started from ~150 °C and ~125 °C, respectively), while significant molecular interactions were identified by FTIR in the cases of PVA-MAN, PVA-SOR and PVA-SUC. Hot-stage polarized microscopy (HSM) revealed PVA's melt miscibility only with MAN and SOR, while melt flow index (MFI) measurements showed that the use of MAN, SOR and PEG400 resulted in a significant improvement of PVA's melt flow properties. Finally, MD simulations were in close agreement with the experimental observations, indicating that they can be considered as a promising tool for the theoretical modelling of such systems.
Keywords: Fusion-based pharmaceutical processes; Melt flow index; Molecular dynamics simulations; Plasticizers; Poly(vinyl alcohol).
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