Supercritical fluid coating of API on excipient enhances drug release

A process to coat particles of active pharmaceutical ingredient (API) onto microcrystalline cellulose (MCC) excipient shows promise as a new way to dosage forms showing enhanced drug release. The process consists of a fluidized bed operated at elevated pressure in which API particles are precipitated from a Supercritical Anti-Solvent process (SAS). MCC particles were used as an excipient in the fluidized bed and collect the SAS-generated API particles. Naringin was selected as the model API to coat onto MCC. A number of operational parameters of the process were investigated: fluidization velocity, coating pressure, temperature, concentration of drug solution, drug solution flow rate, drug mass, organic solvent, MCC mass and size and CO2-to-organic solution ratio. SEM and SPM analyses showed that the MCC particle surfaces were covered with near-spherical nanoparticles with a diameter of approximately 100–200 nm, substantially smaller than the as-received API material. XRD showed that naringin changed from crystalline to amorphous during processing. The coated particles resulting from the SAS fluidized bed process have a higher loading of API, gave faster release rates and higher release ratios in comparison with those produced using a conventional fluidized bed coating process. The approach could be transferred to other industries where release is important such as agrochemical, cosmetic and food

Preparation of multilayer microcapsules encapsulating aqueous lithium bromide and their mechanical stability

The development of more efficient and reliable absorption/adsorption refrigeration for air conditioners (ACs) and chillers is of great interest due to the increasing demand of these cooling devices in homes and offices. Presently, the majority of the ACs incorporate aqueous lithium salts as both refrigerate and desiccant, which are corrosive and lead to corrosion of the mechanical components. This increases maintenance costs and decreases the cooling system’s lifespan. Herein, an encapsulation method is proposed to encompass the aqueous lithium bromide solution with silica as the shell, to protect the surrounding mechanical components. Moreover, a coating of citrate stabilized Au nanoparticles via an electroless method involving intermolecular electrostatic interactions is introduced to improve the robustness of the capsule wall. The success of the different coatings is evident from the change of zeta potential and mechanical properties. The coating with Au nanoparticles improves the mechanical strength of the capsules significantly, increasing rupture force from 0.25 ± 0.02 mN to 0.45 ± 0.04 mN. The coated and uncoated capsules were shown to be thermally stable over 10 repeated cycles between the temperature ranges −10 to 150 °C; hence, they withstand the thermal demands in ACs. Furthermore, adsorption and desorption cycles were performed on the capsules, which showed promising stable and repeatable performance