Aseptic drugs are often difficult to sterilize due to their inherent sensibility to heat-induced degradation. According to Good Manufacturing Practices (GMP), if a terminal sterilization is not possible, filtration through a bacteria retentive filter or aseptic processing is used. Filtration of liquids through 0.2 μm diameter filters is a common method for removing microorganisms from the drug heat-sensitive solutions to obtain sterile filtrate. Actually, final filtration with a 0.2 μm diameter filter is the simplest last unit operations in the process; however, it is a critical step for successful manufacturing. Filter clogging can occur primarily because of molecular aggregation and can result in the deterioration of product quality and longer processing times. This shows the aim of the validation of the sterile filtration which requires many evaluations including a bacterial challenge.