In recent years amorphous solid dispersions (ASD) has gained a tremendous response for improving the solubility of poorly water-soluble drug substances. Despite the stability challenges, various ASD commercial products have been successfully launched into the market over the last two decades. Among various manufacturing approaches, hot melt extrusion (HME) and spray drying techniques have attracted industries attributing to their simple manufacturing processes. In addition, KinetisolÒ, a solvent-free approach, is also being most widely investigated for developing ASDs since the thermal exposure time of the formulations is significantly less compared with the hot melt extrusion process. KinetisolÒ can be employed for developing ASDs of thermolabile drug substances. Another solvent-based technique, electrospinning, is also employed for developing nanofibers-based ASD. However, much research is warranted for the electrospinning process before implementing it in commercial manufacturing. Various critical factors such as drug-polymer solubility, the solubility of the drug in the polymer, drug-polymer interactions, type of manufacturing process, and storage conditions need to be considered for developing a stable and robust ASD formulation. This review mainly focuses on the most advanced manufacturing technologies of ASDs, namely HME, spray drying, KinetisolÒ, and electrospinning, along with a note on the various critical factors that affect the stability of ASD formulations. Keywords: amorphous solid dispersions; hot melt extrusion; spray drying; KinetisolÒ; electrospinning

This study is aimed to develop and evaluate cost-effective cellulose acetate (CA)-polyvinyl pyrrolidone (PVP) film coating that can effectively control the release of freely water soluble drug, metoprolol succinate (MS) and to match that of release profile with its marketed tablet formulation. Simple core tables of MS were compressed and coated with a solution composed of semipermeable rate controlling polymer, CA and water soluble pore forming polymer, PVP. Drug-excipient interaction was investigated by both physical observation and differential scanning calorimetry (DSC). The effect of formulation parameters such as the ratio of CA to PVP, tablet coating weight gain, effect of pH on the in-vitro drug release were evaluated. Surface morphology of the CA coating membrane was examined by scanning electron microscope (SEM). Release profile of the optimized formulation at different pH conditions was determined and the similarity factor (f2) with marketed tablet release profile was calculated. It was observed that drug release rate increased with a decrease in the ratio of cellulose acetate to PVP and decreased with increased weight gain of the coating membrane. Among all the formulations, the formulation with CA and PVP at a ratio of 85:15 %w/w and 9 % weight gain showed matching release profile to the marketed tablet formulation with f2 value of 72.25. Developed MS formulation showed pH independent drug release. This study proved that CA-PVP polymer coating could effectively control the release rate of freely water soluble drugs for up to 24 h. Once a day CR formulation of metoprolol succinate pharmaceutically equivalent to marketed formulation was developed.