One cannot establish the quality of anything without knowing or defining it first. This is simple logic!
However, regulatory authorities, including pharmacopeias, have been trying to prove this logic wrong! That is, they have been making claims of establishing and monitoring the quality of pharmaceutical products such as tablets and capsules – without knowing or defining it. They will fail and have failed!
Logically and/or scientifically, none of the products (approved or otherwise) available on the market can be considered quality. Guidance and compliance-based system, along with the plant inspections, is a thick smoke screen hiding the reality and hindering progress.
Please, define a quality product and set the standards and specifications accordingly so that appropriate quality products can be manufactured and monitored. For further detail, please see here.