What happens while a batch is being made

Testing the end is not controlling the middle

Quality claims in this market are almost always about a finished vial. A number on a certificate, a laboratory named, a test passed.

The federal manufacturing rules put their weight somewhere else. They require written procedures describing the in-process controls, tests or examinations to be conducted on samples of in-process materials of each batch.

Then they say what those procedures are for. Control procedures are established "to monitor the output and to validate the performance of those manufacturing processes that may be responsible for causing variability" in the in-process material and the drug product.

That sentence inverts the usual reading. The process is the thing under examination, and the in-process check is how its performance is demonstrated. The rule even names candidates for where variability comes from, including adequacy of mixing to assure uniformity and homogeneity, the clarity, completeness or pH of solutions, and bioburden testing.

A second paragraph closes the loop. In-process specifications have to be consistent with the final specifications for the product, and derived where possible from previous acceptable process average and process variability estimates.

The procedure comes first, and a departure is written down

The subpart opens with a requirement about paper rather than about product.

There have to be written procedures for production and process control, designed to assure that the drug products have "the identity, strength, quality, and purity they purport or are represented to possess". Those procedures are drafted, reviewed and approved by the appropriate organizational units, and then reviewed and approved by the quality control unit.

The next paragraph carries the enforcement of it. The procedures have to be followed, and performance of them has to be "documented at the time of performance". Not reconstructed afterwards.

And then the clause that does the most work: "Any deviation from the written procedures shall be recorded and justified." A departure is allowed. An unrecorded one is not.

The batch is aimed above the label, not at it

One short sentence in the rules on charging components into a batch explains something a strength figure hides.

The batch "shall be formulated with the intent to provide not less than 100 percent of the labeled or established amount of active ingredient".

The target is a floor rather than a bullseye. Material is lost at every step, and a formulation aimed exactly at the labeled amount would land under it. Aiming above the label is how a finished unit arrives at the number on the carton.

That is worth holding beside a purity or potency figure on a product page. The label amount is what the process is supposed to deliver after losses, and the intent behind the formula is a separate fact from the result of a test.

Two people, again and again

The most repeated idea in this subpart is not a test. It is a second person.

Weighing, measuring and subdividing operations for components have to be adequately supervised. Each container of a component dispensed to manufacturing has to be examined by a second person. That check confirms three things. The component was released by the quality control unit, the weight or measure matches the batch production records, and the containers are properly identified.

Adding a component to the batch works the same way. Each component is added by one person and verified by a second.

So does the arithmetic. Actual yields and percentages of theoretical yield are determined at the conclusion of each appropriate phase. The calculation is either performed by one person and independently verified by a second, or done by qualifying automated equipment.

That automation clause is the interesting part. Where automatic, mechanical or electronic equipment is used in conformity with its own section, it can satisfy those one-person-plus-checker requirements, provided one person checks that the equipment performed the operation properly. The rule does not remove the human check. It moves it onto the machine.

The machine has a number, and the number is in the record

Equipment gets a whole subpart of its own, and two of its requirements are about identification rather than engineering.

All compounding and storage containers, processing lines and major equipment used during production have to be properly identified at all times, to indicate their contents and, when necessary, the phase of processing.

Major equipment has to be identified by a distinctive identification number or code, and that code is recorded in the batch production record to show the specific equipment used for that batch. Where a facility holds only one of a particular type of equipment, its name may be used instead of a code.

A batch record built that way can answer which vessel a batch was made in. That is the kind of question nobody asks until something goes wrong, and it is answerable only if the identification existed at the time.

The subpart also asks for equipment of appropriate design, adequate size and suitable location, judged by two things at once: its intended use, and its cleaning and maintenance.

What is allowed to touch the material

Three requirements sit between the machine and the medicine, and each one is short.

Surfaces that contact components, in-process materials or drug products must not be reactive, additive or absorptive so as to alter the safety, identity, strength, quality or purity of the product beyond established requirements. Readers of the article on labeling and containers will recognize that test, because a separate section applies the same words to the container the product ends up in.

Substances required for the equipment to run are handled next. Lubricants and coolants are named, and they must not come into contact with components, containers, closures, in-process materials or drug products in a way that alters the product beyond established requirements.

Cleaning carries its own written procedures, and three of their required contents are unusually concrete. Removal or obliteration of previous batch identification. Protection of clean equipment from contamination before use. And inspection of equipment for cleanliness immediately before use.

One sentence in this subpart is written for injectables specifically. Filters for liquid filtration used in making injectable products for human use must not release fibers into those products. Where a fiber-releasing filter cannot be avoided, an additional non-fiber-releasing filter follows it, with a maximum nominal pore size rating of 0.2 micron, or 0.45 micron if manufacturing conditions dictate. Asbestos-containing filters are prohibited outright.

A clock on a phase, and what a delay has to carry

Production has a time dimension, and the rules treat it as a quality question rather than a scheduling one.

Where appropriate, time limits for the completion of each phase of production are established to assure the quality of the product.

Deviation from those limits may be acceptable, on one condition: it does not compromise the quality of the drug product. Any such deviation has to be justified and documented.

That is the same pattern as the general deviation clause, applied to the clock. Nothing forbids taking longer. What is forbidden is taking longer without a written reason.

Sterile is a claim about a process

One section separates two microbiological questions that get treated as one.

For drug products that are not required to be sterile, appropriate written procedures designed to prevent objectionable microorganisms have to be established and followed.

For drug products purporting to be sterile, there are appropriate written procedures designed to prevent microbiological contamination. The regulation then adds a requirement to them: "Such procedures shall include validation of all aseptic and sterilization processes."

Validation of the process is written into the rule as part of the procedure, not as an extra. The article on sterility and beyond-use dating covers what that means for a test result and why FDA tells facilities not to cite a passing sterility test as proof of sterility.

What happens to material that does not conform

Two provisions cover the case everybody wants to know about, and they are stricter than the headline suggests.

In-process materials are tested for identity, strength, quality and purity as appropriate, and approved or rejected by the quality control unit during the production process. The rule gives examples of when: at the start or end of significant phases, or after storage for long periods.

Rejected in-process material does not simply get set aside. It has to be identified and controlled under a quarantine system designed to prevent its use in operations for which it is unsuitable.

A batch that does not conform to standards or specifications can be reprocessed. It happens only under a written system that prescribes the steps to ensure the reprocessed batch will meet all established standards, specifications and characteristics.

And the last sentence of the subpart names who decides. "Reprocessing shall not be performed without the review and approval of the quality control unit."

Who these rules bind, and what a reader can do with them

The regulation states its own reach. It contains the minimum current good manufacturing practice for preparation of drug products for administration to humans or animals.

Whether a given compounder is held to it depends on which part of the compounding statute that facility operates under, because the two categories are exempted from different lists of requirements. That comparison is the subject of the article on what a compounding exemption actually exempts.

So this is a reference point rather than a promise about any seller. It describes what a controlled process looks like when somebody is required to build one, and that is the standard a voluntary quality claim can be read against.

Three questions fall out of it. Does the claim describe a result or a process, because these rules treat the process as the thing being demonstrated. Does anything on the page describe what happens when a step goes wrong, since a recorded and justified deviation is the ordinary case rather than a scandal. And is a written procedure claimed at all, because every requirement above begins with one.

Sources

Each document below is named as it names itself, with the date printed on that document rather than the day it was read.

1. Title 21 Code of Federal Regulations Section 211.110, Sampling and testing of in-process materials and drug products, including paragraph (a) requiring control procedures established to monitor the output and to validate the performance of manufacturing processes that may cause variability, and paragraph (d) quarantining rejected in-process material — Office of the Federal Register, Electronic Code of Federal Regulations, September 2026
2. Title 21 Code of Federal Regulations Section 211.100, Written procedures; deviations, requiring procedures reviewed and approved by the quality control unit, performance documented at the time of performance, and every deviation recorded and justified — Office of the Federal Register, Electronic Code of Federal Regulations, September 2026
3. Title 21 Code of Federal Regulations Section 211.101, Charge-in of components, including the formulation intent of not less than 100 percent of the labeled amount and the second-person examination of each container dispensed to manufacturing — Office of the Federal Register, Electronic Code of Federal Regulations, September 2026
4. Title 21 Code of Federal Regulations Section 211.103, Calculation of yield, requiring actual and theoretical yields at the conclusion of each appropriate phase and independent verification by a second person — Office of the Federal Register, Electronic Code of Federal Regulations, September 2026
5. Title 21 Code of Federal Regulations Section 211.105, Equipment identification, requiring containers, processing lines and major equipment to be identified at all times and major equipment to carry a distinctive code recorded in the batch production record — Office of the Federal Register, Electronic Code of Federal Regulations, September 2026
6. Title 21 Code of Federal Regulations Section 211.111, Time limitations on production, permitting deviation from an established time limit only where quality is not compromised and the deviation is justified and documented — Office of the Federal Register, Electronic Code of Federal Regulations, September 2026
7. Title 21 Code of Federal Regulations Section 211.113, Control of microbiological contamination, whose paragraph (b) requires written procedures for products purporting to be sterile to include validation of all aseptic and sterilization processes — Office of the Federal Register, Electronic Code of Federal Regulations, September 2026
8. Title 21 Code of Federal Regulations Section 211.115, Reprocessing, requiring a written system for non-conforming batches and the review and approval of the quality control unit before reprocessing is performed — Office of the Federal Register, Electronic Code of Federal Regulations, September 2026
9. Title 21 Code of Federal Regulations Section 211.65, Equipment construction, requiring product-contact surfaces not to be reactive, additive or absorptive and keeping lubricants and coolants away from components and product — Office of the Federal Register, Electronic Code of Federal Regulations, September 2026
10. Title 21 Code of Federal Regulations Section 211.67, Equipment cleaning and maintenance, including removal of previous batch identification, protection of clean equipment before use and inspection for cleanliness immediately before use — Office of the Federal Register, Electronic Code of Federal Regulations, September 2026
11. Title 21 Code of Federal Regulations Section 211.68, Automatic, mechanical, and electronic equipment, whose paragraph (c) lets qualifying automated equipment satisfy the one-person-and-checker requirements provided one person checks that it performed the operation — Office of the Federal Register, Electronic Code of Federal Regulations, September 2026
12. Title 21 Code of Federal Regulations Section 211.72, Filters, requiring that filters used on injectable drug products for human use not release fibers and prohibiting an asbestos-containing filter — Office of the Federal Register, Electronic Code of Federal Regulations, September 2026
13. Title 21 Code of Federal Regulations Section 211.1, Scope, stating that the part contains the minimum current good manufacturing practice for preparation of drug products for administration to humans or animals — Office of the Federal Register, Electronic Code of Federal Regulations, September 2026