How PepGenex Science classifies evidence

The primary-source rule

Every statement on a PepGenex Science page is tied to a primary source: a peer-reviewed publication identified by its PubMed identifier (PMID) or Digital Object Identifier (DOI), a U.S. FDA record or guidance document, a U.S. regulation, a USP general chapter as named in an FDA document, or an ICH guideline. A statement whose source cannot be verified is left out. It is not reworded to make it easier to support, and a citation is never repaired or guessed.

Verification means reading the source at its primary record. For a journal article, that is the PubMed record or the publisher's record reached through the DOI; for a regulation, the published text; for FDA guidance, the document on fda.gov.

What a SOURCE is

A SOURCE is one citable document. Its record holds the bibliographic details (authors, title, journal or issuing body, year, volume and pages) and its identifiers (PMID, DOI, PubMed Central ID, or a docket or regulation number). Each SOURCE has an evidence type and a date on which it was verified.

A SOURCE is recorded once and can support several statements. When a source is corrected or retracted, every statement that depends on it can be found and reviewed.

What a CLAIM is

A CLAIM is one statement about a compound that a SOURCE supports. It is written as what the study reported, attributed to that study, rather than as a general fact. A CLAIM carries the evidence type of its SOURCE and a display status; only claims marked for display appear on a page.

A CLAIM does not extend a finding beyond the system in which it was observed. A result from a cell assay is described as a cell assay result, and a result in an animal model is described as an animal model result.

The four evidence types

• In vitro: studies in cells, tissues or purified molecules outside a living organism, including binding, signalling and structural studies.
• Animal: studies in living non-human organisms.
• Human: studies in people, from small reports to controlled trials. Human findings are reported as what the study reported, with the study identified.
• Regulatory: records from the U.S. FDA, such as Drugs@FDA entries and the FDA substance registry, and U.S. regulations.

How evidence types are kept apart

Each compound profile groups its studies by evidence type, so an in vitro finding is never presented beside a human finding as if the two were equivalent. Where the evidence for a compound is only in vitro or only in animals, the profile says so.

Structural and mechanism studies explain how a molecule interacts with its target in the system studied. They are not evidence of an effect in a whole organism, and the pages do not present them as such.

How regulatory statements are written

A regulatory statement says only what a Drugs@FDA record or an FDA document states, as verified on the date shown, and cites that record or document. A search that returned no match is not treated as a source. Where the FDA lists an approved product containing the compound, the statement adds that PepGenex research materials are not that product and are not for human or veterinary use.

Regulatory statements do not describe approved indications, do not describe the status of a compound outside the United States, and are not written for compounds whose status could not be verified.

What the pages leave out

PepGenex Science pages do not describe how to handle or use any material, do not recommend any compound, and do not carry prices or links to any catalogue. Page titles and descriptions name the compound or concept, its class, the evidence types covered and the references cited, without study outcomes.

Limitations

A profile is a summary of the sources it cites, not a systematic review. The absence of a study from a profile does not mean no such study exists, and sources are reviewed on the dates shown rather than continuously.

Evidence types describe where a finding was observed, not how reliable it is; a well-conducted cell study and a small uncontrolled human report can each be the only evidence of its type.

Related pages

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