Structural Elucidation of Poloxamer 237 and Poloxamer 237/Praziquantel Solid Dispersions: Impact of Poly(Vinylpyrrolidone) over Drug Recrystallization and Dissolution

Determining the Best Poloxamer Carrier for Thiocolchicoside Solid Dispersions

Objectives

The aim of this study of this study was to discover the best poloxamer as a solid dispersion carrier for thiocolchicoside (TCS).

Materials and Methods

The compatibility of TCS with excipients was studied by differential scanning colorimetry and fourier transform infrared spectroscopy. Different formulations of solid dispersions (SDs) were made with poloxamer carriers, i.e. poloxamer-108, poloxamer-188, poloxamer-237, poloxamer-338, and poloxamer-407 were made by taking TCS:poloxamer in ratios of 1:1, 1:2, 1:4, and 1:6. The SDs were made by a novel microwave fusion method and compressed using an 8-station tablet compression machine. The fabricated SD tablets were characterized by physicochemical constraints and drug release rates. The release of TCS from the prepared SDs was later analyzed by kinetic models.

Results

TCS was observed to be compatible with the poloxamer carriers. The SD formulations showed satisfactory physicochemical constraints and TCS release following first-order release.

Conclusion

Among the poloxamer carriers used, poloxamer-188 was the best for increasing the solubility and release rate of TCS from the SDs.

Insight into the Dissolution Molecular Mechanism of Ternary Solid Dispersions by Combined Experiments and Molecular Simulations

With the increase concern of solubilization for insoluble drug, ternary solid dispersion (SD) formulations developed more rapidly than binary systems. However, rational formulation design of ternary systems and their dissolution molecular mechanism were still under development. Current research aimed to develop the effective ternary formulations and investigate their molecular mechanism by integrated experimental and modeling techniques. Glipizide (GLI) was selected as the model drug and PEG was used as the solubilizing polymer, while surfactants (e.g., SDS or Tween80) were the third components. SD samples were prepared at different weight ratio by melting method. In the dissolution tests, the solubilization effect of ternary system with very small amount of surfactant (drug/PEG/surfactant 1/1/0.02) was similar with that of binary systems with high polymer ratios (drug/PEG 1/3 and 1/9). The molecular structure of ternary systems was characterized by differential scanning calorimetry (DSC), infrared absorption spectroscopy (IR), X-ray diffraction (XRD), and scanning electron microscope (SEM). Moreover, molecular dynamic (MD) simulations mimicked the preparation process of SDs, and molecular motion in solvent revealed the dissolution mechanism of SD. As the Gordon-Taylor equation described, the experimental and calculated values of Tg were compared for ternary and binary systems, which confirmed good miscibility of GLI with other components. In summary, ternary SD systems could significantly decrease the usage of polymers than binary system. Molecular mechanism of dissolution for both binary and ternary solid dispersions was revealed by combined experiments and molecular modeling techniques. Our research provides a novel pathway for the further research of ternary solid dispersion formulations.