Novel Application of Twin Screw Extruder on Production of Diverse Formulations

Twin-screw extruder has attracted considerable attention in the pharmaceutical industry as an alternative processing instrument due to its advantages compared to other conventional equipment, such as economical processing, small footprint, reduced in-process times, solvent-free and continuous processing. These superiorities have led to the application of twin-screw extruder to produce numerous dosage forms, including pellets, tablets and films. Many other formulations production can also be beneficial from the introduction of twin-screw extruder to the process. Nanocrystal formulations are promising drug delivery systems owing to their ability to enhance the bioavailability and maintain the stability of poorly water-soluble drugs. However, conventional methods of preparing nanocrystal formulations, such as spray drying and freeze-drying, have some drawbacks, including high cost, time and energy inefficiency, traces of residual solvent. In this study, twin-screw extruder was combined with high pressure homogenizer to successfully produce nanocrystal solid dispersions (NCSDs). The process could successfully overcome the limitation of conventional methods. Dry granulation process is necessary for some moisture sensitive APIs. However, the widely applied dry granulation technologies, slugging and roller compaction, have some limitations: single batch operation, low manufacturing throughput, high amounts of fines and dust, inferior tensile strength of final tablet and loud operation. The previously unreported study of applying twin screw extruder to the dry granulation process was successfully conducted. The continuous processing nature, simplicity of operation and easiness of optimization made (twin-screw dry granulation) TSDG quite competitive compared to other conventional dry granulation techniques. Kollidon® SR is a polyvinyl acetate (PVAc) and polyvinyl pyrrolidone (PVP) based polymer. The plastic PVAc and sticky PVP make Kollidon® SR an extraordinary option for direct compression of high hardness and low friability tablet. In addition, the low glass transition temperature (Tg) of about 35 oC should make Kollidon® SR a perfect candidate for twin screw extruder. But this application is rarely reported. This study demonstrated Kollidon® SR could be successfully processed by twin-screw extruder to produce tablets, which is compared to the direct compressed counterpart. The physicochemical properties of both products were analyzed. The drug release mechanism was determined

The effects of polydimethylsiloxane on transparent and hydrophobic waterborne polyurethane coatings containing polydimethylsiloxane

The effects of polydimethylsiloxane (PDMS) on phase separation, optical transmittance and surface properties including surface composition, morphology and wettability of waterborne polyurethane (WPU) containing PDMS were investigated. After the introduction of PDMS into the WPU backbone by polymerization, the large difference in the solubility parameter of the non-polar PDMS segment and the high-polar urethane segments promoted PDMS enrichment at the air-polymer interface and enhanced phase separation, resulting in rough structures. Accordingly, the combination of PDMS enrichment and the rough structures contributed to the high or superhydrophobic surfaces and the highest contact angle with water achieved was 156.5 degrees. The optical transmittance of the highly hydrophobic coatings reached about 78-87% throughout most of the visible light region. Importantly, the highly hydrophobic and transparent properties will greatly broaden the applications of WPU, showing potential for the environmental protection and industrial applications

Conjugation of Hot-Melt Extrusion with High-Pressure Homogenization: a Novel Method of Continuously Preparing Nanocrystal Solid Dispersions

Over the past few decades, nanocrystal formulations have evolved as promising drug delivery systems owing to their ability to enhance the bioavailability and maintain the stability of poorly water-soluble drugs. However, conventional methods of preparing nanocrystal formulations, such as spray drying and freeze drying, have some drawbacks including high cost, time and energy inefficiency, traces of residual solvent, and difficulties in continuous operation. Therefore, new techniques for the production of nanocrystal formulations are necessary. The main objective of this study was to introduce a new technique for the production of nanocrystal solid dispersions (NCSDs) by combining high-pressure homogenization (HPH) and hot-melt extrusion (HME). Efavirenz (EFZ), a Biopharmaceutics Classification System class II drug, which is used for the treatment of human immunodeficiency virus (HIV) type I, was selected as the model drug for this study. A nanosuspension (NS) was first prepared by HPH using sodium lauryl sulfate (SLS) and Kollidon® 30 as a stabilizer system. The NS was then mixed with Soluplus® in the extruder barrel, and the water was removed by evaporation. The decreased particle size and crystalline state of EFZ were confirmed by scanning electron microscopy, zeta particle size analysis, and differential scanning calorimetry. The increased dissolution rate was also determined. EFZ NCSD was found to be highly stable after storage for 6 months. In summary, the conjugation of HPH with HME technology was demonstrated to be a promising novel method for the production of NCSDs

Bidirectional Anions Gathering Strategy Afford Efficient Mixed Pb-Sn Perovskite Solar Cells

Abstract Mixed lead-tin (Pb-Sn) perovskite solar cells (PSCs) possess low toxicity and adjustable bandgap for both single-junction and all-perovskite tandem solar cells. However, the performance of mixed Pb-Sn PSCs still lags behind the theoretical efficiency. The uncontrollable crystallization and the resulting structural defect are important reasons. Here, the bidirectional anions gathering strategy (BAG) is reported by using Methylammonium acetate (MAAc) and Methylammonium thiocyanate (MASCN) as perovskite bulk additives, which Ac− escapes from the perovskite film top surface while SCN− gathers at the perovskite film bottom in the crystallization process. After the optoelectronic techniques, the bidirectional anions movement caused by the top-down gradient crystallization is demonstrated. The layer-by-layer crystallization can collect anions in the next layer and gather at the broader, enabling a controllable crystallization process, thus getting a high-quality perovskite film with better phase crystallinity and lower defect concentration. As a result, PSCs treated by the BAG strategy exhibit outstanding photovoltaic and electroluminescent performance with a champion efficiency of 22.14%. Additionally, it demonstrates excellent long-term stability, which retains ≈92.8% of its initial efficiency after 4000 h aging test in the N2 glove box