(83d) Characterization of Pharmaceutical Powders Modified by Dry Coating

Engineered particles, which are surface modified via dry coating have been shown to have improved flow and handling properties, and hence are very useful for a number of industrial applications. Recent work in our group has indicated that dry coating makes it possible to impart improved flowability for blends with very high API contents (higher than 75 %) even for very cohesive micronized API powders. This is very useful for pharmaceutical processing including flow, handling and downstream processing. Although it is clear that these surface modified powders flow better as indicated by reduced angle of repose and faster or more uniform flow out of a funnel, there is an unresolved issue; the extent of powder attrition during surface modification and the influence of size reduction on flow properties that are specifically relevant to industry practice.

Acetaminophen and ibuprofen are considered as model active pharmaceutical ingredients (APIs), and are surface modified via dry coating of nano-additives in several dry coating devices. The study considers use of hydrophobic as well as hydrophilic nano-additives. The resulting powders are analyzed for their particle size distribution, coating coverage, and dispersibility; the latter is evaluated using the Sympatec Helos/Rodos system under varying dispersion conditions. In addition, a suite of techniques are employed for powder flow and other properties which are important for large scale pharmaceutical manufacturing. Extensive powder flow property characterization is done, ranging from novel methods such as vibrated packed density measurements to industry standard technique such as shear testing via the Schulze tester. In addition, other powder properties such as sticking tendency and electrostatic properties are evaluated, and several flow testers are also employed, including the Aeroflow, Freeman Rheometer, and the Hosokawa Powder Tester. The results of these tests are compared with those for untreated API powders in order to examine the influence of surface modification on property enhancements.