| A thorough understanding and precise characterization of powdered excipients and drugs are of great importance to enhance the quality of the final product. Powder compression is a common method to evaluate their properties and behavior. It is essential to understand the elastic, viscoelastic and plastic response of powder to the compression force. A new instrument, the University of Alberta Density Tester, was developed for this purpose. It can be used to measure the Compressed Bulk Density of pharmaceutical powders along with other parameters. A measurement method using low-pressure compaction was implemented. This type of powder characterization method has several advantages. A very small amount of sample is needed which is important when dealing with expensive or scarce samples. Secondly, poorly compactable powders can be analyzed accurately. The importance of the former is evident as powder characterization using traditional methods are restricted by the high amount of sample required. The latter allows analysis of respirable samples where interparticle forces rather than inertial forces become dominant for the compaction behavior. For the same reasons the applicability of the conventional methods like tapped density measurements is questionable. Another advantage of this technique is that the developed instrument is very sensitive and shows significant response to any changes in the testing conditions even if the changes are very slight. Experimental results were fitted to two empirical models, the Heckel and Kawakita models, to evaluate mechanistic behavior of the powders under different levels of compaction. In this study, a novel modulated compaction technique was developed that helps in the interpretation of different compaction stages. Modulated Compression Profiles differentiate between elastic and plastic behavior of powders under compression, which may lead to further development or refinement of compression models that can provide a better understanding of the different compression mechanisms. |
