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Development of hot-melt extrusion as a novel technique for the ...

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properties <strong>of</strong> polymers and excipients required and not suitable <strong>for</strong> relatively high heat sensitivemolecules such <strong>as</strong> microbial species, proteins etc [20, 21] .1.4 Applications <strong>of</strong> HMEExtrusion technology is one <strong>of</strong> <strong>the</strong> most important fabrication processes in <strong>the</strong> pl<strong>as</strong>tic andrubber industries. Products made from <strong>melt</strong> extruded polymers range from pipes to hosesthrough to <strong>the</strong> insulated wires, cables, rubber sheeting and polystyrene tiles. Pl<strong>as</strong>tics that arecommonly processed by HME <strong>technique</strong> include acrylics and cellulosics, polyethylene, polypropylene, polystyrene and vinyl pl<strong>as</strong>tics [9, 22] . In <strong>the</strong> food industry, <strong>extrusion</strong> h<strong>as</strong> been utilized<strong>for</strong> p<strong>as</strong>ta production with a widely used multitalented <strong>technique</strong> combining cooking and<strong>extrusion</strong> in a self-styled <strong>extrusion</strong> cooker [23] . In <strong>the</strong> animal feed industry and veterinary science,<strong>extrusion</strong> is commonly applied <strong>as</strong> a means <strong>of</strong> producing pelletized feeds, implants or injectionmoulding [24] . HME h<strong>as</strong> successfully been applied in <strong>the</strong> <strong>for</strong>mulation <strong>of</strong> f<strong>as</strong>t dispersing PVP <strong>melt</strong>extrudates <strong>of</strong> poorly soluble active agents <strong>as</strong> solid molecular dispersions in <strong>the</strong> crop protectionfield [25] .HME technology h<strong>as</strong> already achieved a strong place in <strong>the</strong> pharmaceutical industry andacademia due to several advantages over traditional processing methods such <strong>as</strong> roll spinningand grinding [18] . In addition to being an efficient manufacturing process, HME enhances <strong>the</strong>quality and efficacy <strong>of</strong> manufactured products and <strong>the</strong>re<strong>for</strong>e over <strong>the</strong> p<strong>as</strong>t few years HME h<strong>as</strong>emerged <strong>as</strong> a <strong>novel</strong> <strong>technique</strong> in pharmaceutical applications [15, 28] . The main use <strong>of</strong> HME is todisperse active pharmaceutical ingredients (APIs) in a matrix at <strong>the</strong> molecular level, thus<strong>for</strong>ming solid dispersions [1, 26] . In <strong>the</strong> pharmaceutical industry, HME h<strong>as</strong> been used <strong>for</strong> variousapplications, such <strong>as</strong> i) enhancing <strong>the</strong> dissolution rate and bioavailability <strong>of</strong> poorly soluble drugsby <strong>for</strong>ming a solid dispersion or solid solution, ii) controlling or modifying <strong>the</strong> rele<strong>as</strong>e <strong>of</strong> <strong>the</strong>drug, iii) t<strong>as</strong>te m<strong>as</strong>king <strong>of</strong> bitter APIs, and iv) <strong>for</strong>mulation <strong>of</strong> various thin films [27] .The bioavailability <strong>of</strong> an active ingredient is controlled by its aqueous solubility.There<strong>for</strong>e, incre<strong>as</strong>ing <strong>the</strong> solubility <strong>of</strong> water insoluble drugs is still a real challenge in <strong>the</strong><strong>for</strong>mulation development process [26] . Due to <strong>the</strong> advent <strong>of</strong> high throughput screening (HTS) in<strong>the</strong> drug discovery process, <strong>the</strong> resultant compounds are <strong>of</strong>ten high molecular weight and highlylipophilic and <strong>the</strong>re<strong>for</strong>e exhibit poor solubility [29] . Scientists have already tried to addresssolubility issues by various pharmaceutical interventions. Among <strong>the</strong> many methods available toimprove solubility and dissolution rate, preparation <strong>of</strong> solid dispersions and solid solutions h<strong>as</strong>gained v<strong>as</strong>t attention. For that re<strong>as</strong>on, HME h<strong>as</strong> been successfully applied to prepare solidmolecular dispersion <strong>of</strong> APIs into different hydrophilic polymer matrices [26, 29] .7 | P a g e

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