Quality Assurance and Quality Control
QA is the system; QC is the evidence
Quality assurance is the whole framework - SOPs, training records, validation, audits, deviation handling, CAPA, change control, and management review. Quality control is the measurement: environmental monitoring results, media fills, gloved fingertip results, end-product testing, and release inspection. A candidate should be able to place an activity in the right bucket and to state what each test actually proves.
End-product testing may include sterility (USP <71>), bacterial endotoxins (<85>), potency and stability, and container-closure integrity, but each test is destructive and samples only part of a batch; sterility testing cannot prove every unit is sterile. That is why process validation - media fill, autoclave and filtration validation (IQ/OQ/PQ), depyrogenation - carries the real weight. A media fill validates the aseptic process and the operator, not a specific batch.
Documentation must allow reconstruction: components, lot numbers, expiry, equipment IDs, operator identity, BUD assignment, temperature and pressure logs, and second-person verification where required.
Traps: responding to a failed sterility test by retesting until it passes; treating a passing media fill as release testing; filing a deviation without a root-cause investigation.
Worked example: a media fill fails for one technician. Investigate technique, gowning, and the PEC; retrain the technician and require a successful repeat media fill before further compounding; quarantine and assess CSPs prepared since the last successful media fill rather than releasing them.