INFLUENCE OF COHESIVE PROPERTIES OF MICRONIZED DRUG POWDERS ON PARTICLE-SIZE ANALYSIS

Particle size analysis results with respect to micronized, mean partic le size below 10 mu m, furosemide, chloramphenicol palmitate and aceta minophen particles are dealt with in this paper. Special consideration was given to the effect of the agglomeration of particles on data gen erated by three size measurement techniques. The physicochemical basis for preparing sufficiently well dispersed and stable suspensions for analysis by employing mechanical methods of pretreatment are shown. Fu rthermore, methods to determine the state of dispersion and methods to assess the individual particle size before size analysis are describe d. An attempt was also made to establish the statistical confidence th at can be assigned to a particular instrument and the confidence level that may be placed on comparative data obtained with the different pa rticle size analysers. Results especially showed the impact of the agg lomeration of very small furosemide particles, mean size 3 mu m, on pa rticle size analysis and the importance of controlling the cohesive pr operties of this drug. To overcome the problems associated with agglom eration more attention must be paid to the physical properties of the drug substance. Combining particle size analysis with bulk: density, s urface area and microscopical studies also helped to identify potentia l problems.