Which type of filter is used for filtration of oily or non aqueous solution for parenteral product?
There are two types of filters, Depth filters and Membrane filters.
Depth filters are seldom used for sterilization. They are constructed of randomly oriented fibers or particles (e.g., diatomaceous earth, porcelain, asbestos) that have been pressed, wound, or otherwise bonded together to form a tortuous pathway for flow. The microorganisms are either entrapped in the path or adsorbed to the filter material. The random structure of material inside the filter creates fluid flow pathways that can vary from extremely narrow to very wide. Filter materials can also break off or come loose during filtration and appear in the filtrate.
The most common screen filter used in compounding is called a “membrane filter.” In terms of structure, membrane filters are thin microporous sheets made from a variety of plastics. Membrane filters must have a nominal pore size of 0.22 microns or less if they are to be used for sterilization. However, membrane filters are available in a wide range of pore sizes from 0.11 to 10 microns.
Selecting the right filter for the process is a key component of many operations. This step is vital to minimizing microbial contamination and ensuring product safety and integrity. Selecting the right filter can significantly impact operational efficiency and cost. Understanding the different criteria for filter selection helps narrow the options and streamlines product selection. There are many options available for today’s manufacturers, and filter selection should be based on filter compatibility, retention requirements, fluid stream characteristics, filter format and scale-up needs.
Sterile Filtration Product Selection Guide of the manufacturer of filters can help you to select appropriate type of fileters as explained above.