ABSTRACT
Sterile products are administered to patients parenterally to achieve both rapid therapeutic response and accurate dosing. Delivery of product in this manner necessarily circumvents the skin, the human body’s primary barrier against infection. The manufacture of sterile products has for decades been intrinsically linked to the expectation that the final dosage form achieves the attribute of sterility. A superficial consideration of the concept of sterility might lead one to believe that it is simple to define what sterility is, and therefore, it must be obvious when a material lacks sterility or sterility assurance. The success criterion for the attribute of sterility is given as either a Probability of a Non-sterile Unit (PNSU) or a Sterility Assurance Level. The minimum expectation for PNSU, which is a probabilistic term properly reserved for physical sterilization methods such as moist heat, is that there must be no greater than one non-sterile unit in one million units.
