Predicting Emulsion Stability with FX-Nano
Particle Size Analysis has always played a large and important role in ensuring the safety and effectiveness of all sorts of pharmaceutical preparations.
The US Pharmacopeia contains a number of particle sizing procedures with drug safety in mind including USP-788 and USP-729. USP-729 requires that the mean droplet size as well as the extent of the large-diameter droplet tail (>5µm) be determined. Conventionally, a method such as dynamic light scattering would be used to determine the mean droplet size and a light obscuration technique would be used to analyze the large-diameter droplet tail. It has been found that by using the FX-Nano which uses focused beam light obscuration it is possible to determine both the mean diameter and large-diameter droplet tail using one characterization technique. This is the first single instrument that would satisfy the requirements for USP-729.
The new focused light obscuration technique extends the lower limit of SPOS technology from 0.5 microns down to 0.15 microns whereby it is now possible to define the primary distribution and also provide count information in the tail of pharmaceutical emulsions. In addition, by focusing the beam of detection to a fine point particles can be sized and counted at concentrations up to 10,000,000 particles/mL. Presently, no other available technique can provide both sets of information. In this study, the focused beam system is used to count and size the primary distribution and large-diameter droplet tail of emulsions and determine their viability according to USP-729.
Figure A shows a representative FX-Nano histogram result of an IVLE. Not only was the mean droplet size determined but also the large-diameter droplet tail. Figure B shows a comparison of three IVLEs with mean diameters of between 0.3-0.35µm. From this data emulsion instability can be predicted. Sample LN clearly shows an increase in oversized particles due to coalescence. The PFAT5 was determined to be greater than the USP 729 limit of