New spray congealing atomizer for the microencapsulation of highly concentrated solid and liquid substances

A new pneumatic atomizer for spray congealing, called wide pneumatic nozzle (WPN), was developed. To evaluate its performance, microparticles containing highly concentrated either solid drug (Propafenone hydrochloride, PRF) or liquid nutraceutical (Vitamin E, VE) have been prepared and characterized. The results showed that the spray congealing nozzle enabled the production of spherical and not aggregated microparticles with high yields (95% w/w) and relatively narrow size distributions; moreover, increasing the viscosity of the suspension from 50 to 500 mPa s, the particle size increased. The loading of the drug was high for microspheres (50% for PRF and 30% for VE) and the encapsulation efficiency was good for all formulations. The drug release was easily modified according to the nature of the used excipients, as both lipophilic (carnauba wax, cetearyl and stearyl alcohols) and hydrophilic (PEG 4000) carriers were employed. Moreover the results evidenced that it was possible to encapsulate actives (VE) that are in a liquid form and to enhance their availability. In conclusion the developed spray congealing nozzle was able to nebulize very viscous systems that are usually not processed by conventional apparatus and to produce microspheres with high and uniform drug content.