Five lines that would change what a certificate is worth

In the first quarter the Journal wrote to twenty companies whose names appear on labels in this market and asked five questions. Is the fill aseptic or terminal. Is bioburden determined before sterilising filtration, and to what specification. Is the sterilising filter integrity-tested post-use. Has an aseptic process simulation been performed, at what scale and with what result. Is bacterial endotoxin determined on the finished product, by which method, against which limit. We committed in advance to printing every answer verbatim and every refusal as a refusal.

Bioburden, and why the number before the filter matters

A sterilising filter is not an unlimited barrier. Its qualification is expressed as a retention capability under a defined challenge — conventionally a high titre of a small bacterial species per square centimetre of membrane — and its performance in use depends on the load presented to it. A bulk solution carrying a heavy microbial burden presents a filter with a harder problem than one carrying a light burden, and it presents a second problem the filter cannot address at all: the endotoxin released by organisms that die upstream passes through the membrane unimpeded.

Regulated manufacture therefore specifies a pre-filtration bioburden limit, tests against it on every batch, and treats an excursion as an investigation rather than a curiosity. The specification is usually expressed in colony-forming units per hundred millilitres, and a well-controlled process runs far below it.

Of the twenty companies the Journal wrote to, four stated that pre-filtration bioburden is determined on every batch, three stated that it is determined periodically, and the remainder did not answer the question. We regard that distribution as the single most informative result of the correspondence, because bioburden testing is inexpensive, is performed on the bulk rather than the finished container, and is the earliest point at which a problem is cheap to fix.

Recombinant factor C, and the end of an awkward supply chain

The lysate on which conventional endotoxin testing depends is harvested from horseshoe crabs, which are bled and returned to the sea with a mortality that is disputed and not negligible. The assay also inherits the biological variability of a natural product: lysate lots differ, and the cascade includes a branch responsive to beta-glucans, which is a common source of false positives in the presence of cellulose filter residues.

Recombinant factor C reagents replace the harvested cascade with an expressed enzyme, activated by lipopolysaccharide and read chromogenically or fluorimetrically. The response is specific to endotoxin and insensitive to the glucan branch, lot-to-lot consistency is a manufacturing rather than an ecological question, and comparative studies across a wide range of matrices have found agreement with conventional methods well within the variability of the conventional methods themselves.

The reagent has been available for well over a decade and its slow adoption was a regulatory rather than a scientific matter: for years it sat in an alternative-method chapter, obliging users to validate it as a departure. That has now changed, with dedicated chapters in both the United States and European compendia treating recombinant reagents as methods in their own right, and the Journal expects the harvested lysate to become the historical option within this decade.¹²

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.

What surprised us most in the correspondence was how readily the companies with real fill operations answered. Filter integrity testing, bioburden specifications and media fill records are the ordinary furniture of a working facility, and describing them takes a paragraph. The pattern in our results is less an argument about candour than an argument about what kind of operation is behind a given label.