Formulation and processing technologies for dissolution enhancement of poorly water-soluble drugs
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The number of newly developed chemical entities exhibiting poor water solubility has increased dramatically in recent years. In many cases this intrinsic property results in poor or erratic dissolution in biological fluids. Improving aqueous solubility of these compounds, even temporarily, can have a significant impact on in vivo performance. Single phase amorphous solid dispersions of a drug and polymer have emerged as a technique to not only increase the level of drug supersaturation but also maintain these levels for extended periods of time. Hot-melt extrusion (HME) has become the preferred processing technique to prepare systems such as these but has a number of limitations that prevent the successful formulation of many drug substances. Within this dissertation, the use of concentration enhancing polymers was investigated in parallel with a thorough evaluation of a novel fusion-based processing technique, KinetiSol® Dispersing (KSD), to prepare single phase amorphous solid dispersions that could not be successfully prepared by HME. Studies showed that the KSD technique is suitable for rendering thermally labile and high melting point drug substances amorphous through a combination of frictional and shearing energy. Compounds such as these were shown to degrade during HME processing due to relatively long residence times and low shear forces. Similarly, the KSD process was shown to successfully process solid dispersion compositions containing a high viscosity polymer with significantly lower levels of polymer degradation than obtained by HME processing. In the final study, KSD processing was used to prepare solid dispersions containing the hydrophilic polymer Soluplus[superscript TM] and methods were evaluated to formulate a tablet with rapid tablet disintegration characteristics, a requirement for sufficient dissolution enhancement. Combined, the studies demonstrated the effectiveness of combining proper polymer selection and formulation approaches with a suitable processing technique to form solid dispersion systems that provide rapid and extended durations of supersaturation.