GMP Primer: Contamination Control Training
Last week, we began a discussion of training employees in the basics of contamination control, including definitions, control methods and personnel responsibilities. In this issue, we’ll continue the subject, covering cleaning, sterilizing and storage.
Part Five: Precision Cleaning and Disinfecting
Even using the most sophisticated contamination control system, some elements still can slip through, which is where precision cleaning comes in. Vacuuming is likely to remove less than 10 percent of particles, so wiping down equipment and surfaces with chemical cleaning solutions is necessary.
Cleaning agents are composed of one or more solvents, including water, and surface active agents – normally called surfactants. These solutions work by first breaking the surface tension that binds the contaminating particles to a surface then suspending them in the solution, ready to be removed by the mechanical action of wiping.
In addition to particle contaminants, equipment and facilities must be free of unwanted microorganisms. Disinfectants are used to remove conditions under which microorganisms thrive. But even the most effective disinfectant can only reduce microorganisms to an acceptable scale rather than eliminating them completely. The acceptable level depends on the nature of the microorganism and its ability to harm the product being manufactured.
Part Six: Sterilization
Materials that must be complete free of organisms need to be sterilized. The method of sterilization used depends on the composition of the material being treated. Common methods include:
- Dry heat; and
Steam sterilization, known as autoclaving, is commonly used unless the material being treated is susceptible to damage due to heat and moisture. This method quickly destroys all microorganisms.
Dry heat is used for substances containing oils, powders, sharp instruments or glassware.
Unlike steam and dry heat, filtration does not destroy contaminants, it removes them. Liquid and gas products are passed through a porous filter that traps the microorganisms or retains them on the filter surface.
Part Seven: Storage and Usage of Equipment and Materials
Once contaminants are destroyed (or reduced to an acceptable level), equipment and materials must be stored in a manner that prevents recontamination.
The period of time between the cleaning of equipment and any subsequent use is called “clean hold time.”
During that time, equipment must be stored in class 100,000 areas, where there are fewer than 100,000 particles per cubic foot of air and 20 air changes per hour. It also should be stored dry unless it is in a solution.
Products should be stored off the floor in segregated areas to avoid cross contamination. Storage temperature differs depending on the products’ needs. Certain products also need to be stored with the proper supply of filtered air and suitable measures for dust control.
Finally, any sampling and dispensing of sterilized materials must also be conducted under aseptic conditions.
The complete Contamination Control training package, including slides, leader’s script and knowledge assessment, is available as part of the FDAnews Customizable Training Series for drug manufacturers and devicemakers.