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In previous work, the relative performance of various methods used to characterize the particle size distribution of powders composed of fine irregularly shaped particles was assessed. It was found that methods employing Fraunhofer diffraction theory were inferior with respect to particle counting methods. Furthermore, calculated particle size distributions varied considerably between manufactures of Fraunhofer devices. It is well known that the Mie optical model can also be used to analyze the data collected by laser diffraction instruments. Here, we have compared particle size distributions collected using two Laser diffraction instruments to those determined by the Aerosizer. In our earlier work the Aerosizer was shown to produce results nearly identical to those determined by image analysis. The results of this study indicate that the use of the Mie optical model does not correct for deficiencies previously noted for laser diffraction methods. Considerable variation exists between the results obtained on laser diffraction instruments manufactured by different companies. Our earlier recommendation to use extreme caution when employing laser diffraction instruments to characterize fine powders continues to be supported in the present work.

The particle size distribution of component materials can be important parameter governing the proper function of many industrial products. At present, accurate determination of particle size by currently available methods is difficult for both theoretical and practical reasons. In this paper, some elementary notions regarding particle sizing are reviewed as is the relative performance of commercially available particle sizing instrumentation which could be used for particle size analysis of dry powders. Our results indicate that various par-ticle size instruments yield significantly (even vastly) different particle size distributions for the same material. Without great care on the part of the investigator, the results obtained from any given instrument may not accurately describe the powder in question and thus may cause incorrect technical recommendations. The use of Fraunhofer diffraction instruments on samples containing irregularly shaped small ( < l o pm) particles of low refractive index requires considerable caution. 0 VCH Verlagsgesellschaft mbH, D-69469 Weinheim, 1995 0934-0866/95/0510-0217 $5.00 + .25/0

The concepts of particle engineering and dosage form design have become dominant themes in pharmaceutical manufacturing. This trend is not simply a reflection of the development of new, more sophisticated manufacturing methods of particles or dispersed systems but also recognition of the importance of quality control even in more traditional manufacturing processes. However, the diversity of particle treatments, methods of particle size analysis, expression and interpretation of data, and process applications results in complicated and sometimes confusing criteria for selection, adoption, or relevance of the available techniques.

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Objective. To determine whether there is a difference in pass rates on the North American Pharmacist Licensure Examination (NAPLEX) between students who did and did not require remediation for deficient course grades. Methods. Student-specific data were collected regarding course grade deficiencies and completion of a comprehensive examination or course for remediation. Student-specific first-time NAPLEX performance data for the graduating classes of 2008, 2009, and 2011were provided by the National Association of Boards of Pharmacy (NABP). Results. A significant difference was found in first-time NAPLEX mean pass rates between students who did not need to undergo remediation versus those who did ( 97% vs 70%). Conclusion. Students requiring remediation for deficient course grades had a lower pass rate on the NAPLEX compared with those who did not require remediation. The difference can be attributed to several factors and therefore further study is needed.