How to read the silence on a certificate you already hold

Eleven of the twenty replied within the month. Of those, four answered all five questions, three answered between one and three, and four replied to say that the questions did not apply because the products are sold for research use and are not represented as sterile injectables. That last answer is legally accurate and it is the most important sentence in this article, because it describes precisely the gap between what is being sold and what buyers believe they are buying.

Sterile is a claim about a process

In ordinary speech, calling something sterile describes a state. In pharmaceutical manufacture it describes a provenance. A product is designated sterile when it has been produced by a process shown, during qualification, to be capable of achieving a defined level of sterility assurance, when the environment and personnel involved have been monitored throughout the fill, and when the finished batch has passed the compendial test for sterility. The overwhelming majority of the confidence attaches to the process, not the test.

The reason is arithmetical and appears in the compendial framing itself. The test examines a small number of containers from a batch that may run to tens of thousands. Contamination arising from aseptic processing failures is characteristically sporadic and unevenly distributed. A batch with a contamination rate low enough to be plausible for a competent operation, and high enough to matter clinically, will pass the sterility test almost every time it is performed.¹

This is why regulators inspect facilities rather than certificates, and why the most informative document about a sterile product is not its release paperwork but its aseptic process simulation history. Neither is available to anybody buying research peptides.

Container closure integrity, method by method

The compendial guidance divides leak test methods into probabilistic and deterministic families and is explicit about preferring the second. Probabilistic methods — dye ingress under vacuum, microbial immersion challenge, bubble emission — rely on a sequence of stochastic events, and their sensitivity is poor and hard to quantify. A dye ingress test can pass a container with a defect large enough to admit an organism, because the dye happened not to travel.

Deterministic methods measure a physical quantity with a continuous response. Vacuum decay monitors pressure rise in an evacuated test chamber. High-voltage leak detection measures current through the container wall and is well suited to liquid-filled units. Laser-based headspace analysis interrogates the gas inside a sealed container non-destructively, which permits repeated measurement of the same unit across a stability programme. Helium mass spectrometry resolves the smallest defects of any method in routine use.

The threshold that matters is the maximum allowable leakage limit — the defect size below which microbial ingress does not occur under the conditions the product will see. Establishing it for a given package is a piece of work, and once established it converts an argument about seals into a measurement.²

Documentation practice, named and criticised

The Journal tracks the release documentation of twenty companies. On sterility and endotoxin the picture is close to uniform. Every one publishes a purity figure. A minority publish an identity confirmation. Two publish peptide content. On the microbiological attributes, the standard document is silent, and the silence is not annotated: there is no line reading that sterility has not been determined, which would at least be informative.

Some of the practices we would like to see are already in use somewhere in the group. SSA reports peptide content on its certificates, having begun after correspondence with this publication. CPC and SWB describe their fill environment in general terms on request. QST and BCH answered our five questions in full. WXT and FGP declined on the grounds that research-use products are not represented as sterile injectables, which is a legally sound answer that concedes the point of the exercise. Several others did not respond, and we record non-response as non-response rather than as evasion.

What we are criticising is a documentary convention, not the conduct of any company named here. None of the twenty has been shown to us to have misrepresented anything. The convention is that a chemistry certificate stands in for a release package, and it is a convention this trade adopted collectively and could abandon the same way.

Five lines that would change what a certificate is worth

Nothing the Journal asks for here requires a regulator, an inspectorate or a change in the law, and none of it is commercially sensitive. All five items are already known to whoever released the batch.

First, state the fill route: aseptic or terminal, and if aseptic, in what class of environment. Second, state the pre-filtration bioburden result against its specification, or state that bioburden is not determined. Third, state whether the sterilising filter was integrity-tested after use. Fourth, report bacterial endotoxin per milligram of peptide, with the method and the inhibition-enhancement result, or state that it was not determined. Fifth, where a sterility test has been performed, state the batch size, the number of containers tested and the method, so that a reader can do the arithmetic in the section above. Every one of the five is an ordinary element of a release specification for a biological product, and none of them is an invention of this publication.³

A certificate carrying those five lines would remain a one-page document and would be worth several times what the current one is worth, principally because four of the five lines are permitted to say no. A stated negative is a fact a reader can use. An omission is a space a reader fills with an assumption, and the assumption is always more favourable than the truth would have been.

What this article is not asserting

Precision about the scope of a criticism is part of the job, so it is worth spending a paragraph on what is not being said. This piece does not allege that any company named in it has sold contaminated material. It does not allege that any of them has concealed a result, falsified a document or misrepresented a test. It does not claim that the products discussed are dangerous, and it does not claim that they are safe, because neither claim is supportable from the evidence we have.

What the piece asserts is documentary. A certificate describing chemistry is being read as a release package covering microbiology. That mismatch is created by the format of the document rather than by anybody’s intent, and it is closed by adding lines rather than by changing behaviour.

There is also a legal point the Journal has no wish to elide. Research-use-only material is not approved for human use in any jurisdiction, is not required to meet parenteral standards, and is not represented by its sellers as meeting them. Everything in this article about endotoxin limits and sterility assurance describes the framework that would apply to a parenteral medicine. Applying that framework to a research chemical is a comparison, not a compliance requirement, and readers should hold both halves of that sentence at once.

A note on method and sourcing

The compendial material in this article is drawn from the current general chapters of the United States Pharmacopeia and the European Pharmacopoeia, read in the original rather than in summary, and from the international standards on aseptic processing and on laboratory competence. Where a chapter has changed status recently — as the recombinant reagent chapters have — we say so, because a reader consulting an older edition will find a different framing.

Where the Journal reports a number it obtained itself, it states the laboratory’s accreditation status, the method family, whether method suitability was established, and the number of determinations. Where we report what a company told us, we distinguish an answer from a refusal and a refusal from a non-response, because those three things are routinely collapsed in coverage of this trade and they are not the same.

Corrections to this department are handled by the standards desk, which reads every letter and records the outcome in the log. Readers who believe a paragraph here overstates its evidence are asked to write to standards@compoundjournal.com; readers with documents to send, including certificates they would like read, should write to letters@compoundjournal.com. We do not publish correspondents’ names without permission and we do not identify the source of a certificate.

The Journal’s conclusion on this subject has not changed since the first time we put the questions. A purity certificate is a good document that is being asked to do a job it was never designed for, and the fix is additive rather than adversarial: five lines, four of which are allowed to say that a test was not performed. Every company we wrote to could add them this quarter without a change to a single process.