PVP/aprepitant microcapsules produced by supercritical antisolvent process.

The supercritical antisolvent (SAS) process was a green alternative to improve the low bioavailability of insoluble drugs. However, it is difficult for SAS process to industrialize with limited production capacity. A coaxial annular nozzle was used to prepare the microcapsules of aprepitant (APR) and polyvinylpyrrolidone (PVP) by SAS with N, N-Dimethylformamide (DMF) as solvent. Meanwhile, the effects of polymer/drug ratio, operating pressure, operating temperature and overall concentration on particles morphology, mean particle diameter and size distribution were analyzed. Microcapsules with mean diameters ranging from 2.04 µm and 9.84 µm were successfully produced. The morphology, particle size, thermal behavior, crystallinity, drug content, drug dissolution and residual amount of DMF of samples were analyzed. The results revealed that the APR drug dissolution of the microcapsules by SAS process was faster than the unprocessed APR. Furthermore, the drug powder collected every hour is in the kilogram level, verifying the possibility to scale up the production of pharmaceuticals employing the SAS process from an industrial point of view.

Enhancement of Clathrate Hydrate Formation Kinetics Using Carbon-Based Material Promotion.

Although hydrate-based technology has been considered as a safe and environmentally friendly approach for gas storage and transportation in recent decades, there are still inherent problems during hydrate production, such as a long induction time, slow formation kinetics, and limited hydrate storage capacity. Attempts to resolve these issues have resulted in the development of various kinetics promoters, among which carbon-based materials have become one of the most attractive owing to their unique promotion effect. Herein, results on promotion by bulk wetted carbon materials in the forms of a packed bed, carbon particles in a suspension, and nano-carbon materials in a nanofluid are collected from the published literature. Meanwhile, the promotion mechanisms and influencing factors of the carbon-based promoters are discussed. The purpose of this mini-review is to summarize recent advances and highlight the prospects and future challenges for the use of carbon-based materials in hydrate production.