4 Controlling Contaminants The production of sterile products should be carried out under high levels of air cleanliness. Contamination of raw materials, finished goods, or personnel must be avoided at all times through the implementation of appropriate technical and organizational measures. The significance of such contamination risk may vary with the type of contaminant and the product that is being contaminated, but reliable airborne contamination control remains critical in all situations. Quality of Medicinal Products Everything that could come into direct contact with a pharmaceutical product is a potential risk toward contamination. Limiting exposure to airborne contaminants is critical, as it may result in health and safety issues. Preventive measures and quality management procedures are described in several industry guidelines: “CFR—Code of Federal Regulations Title 21”, “Guidance for Industry—Sterile Drug Products Produced by Aseptic Processing—Current Good Manufacturing Practice 2004”, and “European Union (EU) Guidelines to Good Manufacturing Practice (GMP) Medicinal Products for Human and Veterinary Use—Annex 1—Manufacture of Sterile Medicinal Products, 2008”. These guidelines are to ensure consistent production and control of pharmaceutical products for human use. Air filtration plays a critical role in making sure that these objectives are met and that the risk of any adverse effects on product quality is reduced. Mechanical Strength Reduces Contamination Risks Following the recognized US guidance for Sterile Drug Products Processing, HEPA filters should be tested twice a year for leaks, to demonstrate filter integrity. A critical leak is given when more than 0.01 percent of the upstream aerosol challenge penetrates a test spot. If a critical leak has been determined, it is customary to evaluate a possible impact on sterile processing. If a local defect is detected, this would require a filter repair or replacement, retesting, and finally the evaluation of possible effects on the production line in question. To avoid leaks, the extremely sensitive surface of traditional HEPA filters used to be protected by a grid on the filter surface. New HEPA filters with the latest generation of membrane media represent a better solution, due to considerably improved mechanical strength and reduced pressure difference, thus increasing the economy and quality of sterile production units. The higher costs of such new filters are justified, since the risk of damages will be considerably reduced. Dr. Lothar Gail GMP and cleanroom consultant VDI.
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