Safety, Identity, strength, purity and quality. Anyone working in the business knows that the firm must meet SISPQ as an expectation of quality and that meeting the current Good Manufacturing Practices (cGMPs) are a requirement to demonstrate SISPQ. However, where is this requirement stated?
As codified in 21 CFR 210.1(a):
The regulations set forth in this part  and in parts 211, 225, and 226 of this chapter contain the minimum current good manufacturing practice for methods to be used in, and the facilities or controls to be used for, the manufacture, processing, packing, or holding of a drug to assure that such drug meets the requirements of the act as to safety, and has the identity and strength and meets the quality and purity characteristics that it purports or is represented to possess.
But what happens if a company regulated by USFDA does not meet SISPQ?
As codified in 21 CFR 210.1(b):
The failure to comply with any regulation set forth in this part  and in parts 211, 225, and 226 of this chapter in the manufacture, processing, packing, or holding of a drug shall render such drug to be adulterated under section 501(a)(2)(B) of the act and such drug, as well as the person who is responsible for the failure to comply, shall be subject to regulatory action.
Note: Bold and [ ] added by the author.
The bulk of the regulations that govern drug manufacturing is contained in 21 CFR 211, but 210 contains the above definitions in 210.1, who is applicable to the cGMPs (210.2), and definitions in section 210.3.
The cGMPs as codified by 21 CFR 210 and 211 (and others as applicable) are the minimum requirements necessary to demonstrate that the drug products meet SISPQ. After all, it is impossible to test 100% of the drug products – if we did there would not be any medicines available for use. A commitment to manufacturing quality keeps the drug products safe for the patients. As referenced in The American Druggest, 1977 “The One the Patient Takes is Never Tested” – Eli Lilly & Co advertisement.
The initial commissioning, qualification, and validation activities completed under Stage 2 – Process Qualification* demonstrate the manufacturing facility can produce drugs under the cGMps that meet SISPQ. While Stage 3 – Continued Process Verification* ensures the facility continues to meet these requirements.
*Process Validation: General Principles and Practices USFDA January 2011.