Process monitoring systems
The author's experience has shown that there are important considerations to take into account when designing, implementing,
and operating process monitoring systems. The first of these is process understanding—that is, a deep knowledge of the variables
that drive the process, which enables the accurate prediction of process performance. Effective application of QbD will result
in better process understanding.
It is also crucial to understand the sources and magnitudes of measurement variation, in particular the repeatability and
reducibility of the measurement of the process parameters. Gage R&R studies are an effective method for measuring the repeatability
and reproducibility of the measurement methods used (6). Ruggedness studies are effective for determining method robustness
for measuring typical variations that occur during the routine use of the method (8).
A systematic method is necessary to keep track of special-cause variation and to determine whether a systemic problem exists.
This information can then be used to improve the process.
Two problems often observed related to monitoring systems include data not being analyzed routinely, and not taking action
when significant sources of variation are identified. Regular management review and accountability can address both problems.
When a systematic approach is used, including regular review and action, the result is effective process monitoring. More
importantly, high-quality pharmaceuticals are provided to the patient.
Ronald D. Snee, PhD, is founder and president of Snee Associates, 10 Creek Crossing, Newark, DE 19711, Ron@SneeAssociates.com
1. R.D. Snee, Pharm. Technol. 33 (10), web exclusive, (2009).
2. J.C. Berridge, Pharm. Engin. 36–39 (2009).
3. J. Oakland, Statistical Process Control (Elsevier, New York, NY 2008).
4. D.C. Montgomery, Introduction to Statistical Quality Control, 6th Edition (John Wiley and Sons, New York, NY, 2009).
5. R.D. Snee and R.W. Hoerl, Leading Six Sigma—A Step by Step Guide (FT Press, Prentice Hall, New York, NY, 2003).
6. R.D. Snee and R.W. Hoerl, Six Sigma Beyond the Factory Floor: Deployment Strategies for Financial Services, Health Care and the Rest of the Real Economy (FT Pearson, Prentice Hall, New York, NY, 2005).
7. R.D. Snee and E. C. Gardner, Quality Progress 56–59 (2008).
8 M. Schweitzer et al., Pharm. Technol.
34 (2) 52–59 (2010).