Validating Sterile Filtration: Overcome the Fear of Failure 4

“I need an absolute 0.1- or 0.2-µm-rated filter.”
 
 As a former FDA authority, since retired, once observed, “The word ‘absolute’ should be used only in conjunction with vodka.” Absoluteness implies a complete independence from conditions, an inherent ability to retain particles larger that than the filter’s pore size rating, regardless of any other considerations. Without a complete knowledge of the properties of the particles and filter pores at our disposal, the statement is devoid of technical significance or guidance. It may, perhaps, be used in ignorance (although cynics may suspect that its utility derives from marketing efforts, a practice not unknown in the competitive world of sales.)
Control vs. Fear
As Sandman elucidated, human beings like to be in control, and, if this status cannot be achieved, may move rapidly to fear. Unfortunately, when sterile filtration is concerned, fear can result in the installation of wasteful, unnecessary safety nets that can create more problems than they solve.
Being in control is the desired state, and such control can only come from process validation studies. Their authority is at least as old as Lord Kelvin’s basic scientific principle, “When you can measure what you are speaking about, and can express it in numbers, you know something about it.”
It speaks to validation. In sterile filtration, as in most areas of pharmaceutical manufacturing, science-based validation is the best cure for fear.

References
1. Hessler, A., Sandman, P.M. Squeaky Clean? Not Even Close. http://www.nytimes.com/2004/01/28/dining/squeaky-clean-not-even-close.html?sec=health?pagewanted=1
2. FDA. Guideline on General Principles of Process Validation, FDA CDER, 1987.
3. Agalloco, J.P. “Compliance Risk Management Using a Top-Down Validation Approach,” Pharmaceutical Technology, July 2008.
4. PDA Technical Report 26 (2008), Sterilizing Filtration of Liquids, Parenteral Drug Association, Bethesda, MD.
5. Ridgway, H.F., Rigby, M.G., and Argo, D.G. “Adhesion of a Mycobacterium to Cellulose Diacetate Membranes Used in Reverse Osmosis.” Applied and Environmental Microbiology 47, 1984, pp. 61-67.
6. Tolliver, D.L. and Schroeder, H.G. “Particle Control in Semiconductor Process Streams.” Microcontamination (l), 1983, pp. 34-43 and 78.
7. Bowman, F.W, Calhoun, M.P. and White, M. “Microbiological Methods for Quality Control of Membrane Filters.” J. Pharm. Sci., 56/2, 1967, pp. 453-459.
8. Leahy, T.J., Sullivan, M.J. “Validation of Bacterial Retention Capabilities of Membrane Filters.” Pharmaceutical Technology 2(11), 1978, pp. 64-75.
9. FDA. Guideline on Sterile Drug Products Produced by Aseptic Processing, FDA CDER, 1987.
10. Sundaram, S., Eisenhuth, J., Howard Jr., G.H., and Brandwein, H. “Part 1: Bacterial Challenge Tests on 0.2 and 0.22 Micron Rated Filters.” PDA Journal of Pharmaceutical Science and Technology, 55 (2), 1984, pp. 65-86.
11. Sundaram, S., Auriemma, M., Howard Jr., G.H., Brandwein, H., and Leo, F. “An Application of Membrane Filtration for Removal of Diminutive Bioburden Organisms in Pharmaceutical Products and Processes,” PDA Jour. Pharm. Sci. and Technol. 53 (4), 1999, pp. 186-201.
12. Krygier, V. Rating of Fine Membrane Filters Used in the Semiconductor Industry, Transcripts of Fifth Annual Semiconductor Pure Water Conference, (1986), pp. 232-251, San Francisco, CA
13. PDA/FDA Special Scientific Forum, Bethesda, MD; Validation of Microbial Retention of Sterilizing Filters, July 12-13, 1995.
14. Mittleman, M.W., Jornitz, M.W., Meltzer, T.H., “Bacterial Cell Size and Surface Charge Characteristics Relevant to Filter Validation Studies,” PDA Jour. of Pharm. Sci. and Technol. 52 (1), 1998, pp. 37-42.
15. Agalloco, J., Letter to the Editor—re: “It just doesn’t matter, It just doesn’t matter, It just doesn’t matter.” PDA Journal of Science and Technology. Vol 52, No. 3, pp. 149-150.