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Research use only (RUO)

Research use only (RUO) is a labeling category meaning that a product is labeled as intended for research and not for other uses. In U.S. regulations for in vitro diagnostic products, 21 CFR 809.10(c)(2)(i) sets out the statement "For Research Use Only. Not for use in diagnostic procedures." for products in the laboratory research phase of development.[1]

Where does the phrase come from in U.S. regulations?

21 CFR 809.10 is the labeling regulation for in vitro diagnostic products. Paragraph (c)(2)(i) gives the research use only statement and paragraph (c)(2)(ii) gives the investigational use only statement for products being shipped or delivered for product testing.[1]

Does the label alone determine regulatory status?

No. The label alone does not determine regulatory status. Under 21 CFR 201.128, intended use refers to the objective intent of the persons legally responsible for the labeling of a product, which may be shown by their expressions, by the design or composition of the article, or by the circumstances surrounding its distribution.[2]

FDA guidance on in vitro diagnostic products labeled research use only states that intended use may be determined by looking at the totality of circumstances surrounding distribution, and that overt expressions by a manufacturer can show that a product is actually intended for clinical use despite the RUO or IUO labeling.[3]

What kinds of statements does FDA regard as conflicting with RUO labeling?

The FDA guidance gives examples including statements in labeling, advertising or promotion that claim or suggest a clinical use, clinical interpretive information and discussion of clinical significance.[3]

The same guidance states that, where use is limited to laboratory research unrelated to the development of in vitro diagnostics, instructions for using a product in a research manner, such as mixing proportions, incubation times and storage conditions, would be considered consistent with research use only labeling.[3]

FDA states that it intends to consider the totality of the circumstances concerning a manufacturer's sale and distribution of a product labeled RUO when deciding whether regulatory action is warranted, and recommends that manufacturers assess those circumstances to ensure they are not engaging in practices that conflict with their labeling.[3]

How are approved drugs regulated, and what does a label settle?

An approved drug reaches the market under an application reviewed by FDA: 21 CFR part 314 sets out the procedures and requirements for submitting applications to market a new drug under section 505 of the Federal Food, Drug, and Cosmetic Act, and for FDA's review of those applications.[4]

Which provisions apply to a particular product, and with what result, depends on facts about that product and its distribution that a label does not settle. This page does not reach that conclusion for any product.[2],[3]

How does PepGenex use the term?

PepGenex labels its materials for research use only and not for human or veterinary use; the notice on these pages reads "FOR RESEARCH USE ONLY. NOT FOR HUMAN OR VETERINARY USE. NOT FOR HUMAN CONSUMPTION." The pages on this site describe compounds and analytical concepts from published sources and do not describe how to handle or use any material.

Limitations

21 CFR 809.10 and the 2013 FDA guidance are written for in vitro diagnostic products. They are cited here because they define the RUO statement and describe how FDA reads intended use; they are not the regulations that apply to every product carrying a research use only label.[1],[3]

The regulations are cited in their 2025 editions and the guidance in its November 2013 version; later changes are not reflected here.[1],[2],[3]

21 CFR part 314 is cited in its current edition as read on 2026-09-26. Describing a regulation here is not a statement that it applies to, or has been met for, any product, including any PepGenex material.[4]

This page is general information about a labeling term. It is not legal advice and does not state the regulatory status of any specific product.

Compound profiles

Research peptide profiles in this library. What this page describes applies to peptide lots in general; none of these profiles reports a result of it for any lot.

References

  1. 21 CFR 809.10, Labeling for in vitro diagnostic products (2025 edition), paragraphs (a)(9) and (c)(2)(i)-(ii). 21 CFR 809.10
  2. 21 CFR 201.128, Meaning of "intended uses" (2025 edition). 21 CFR 201.128
  3. U.S. FDA. Distribution of In Vitro Diagnostic Products Labeled for Research Use Only or Investigational Use Only. Guidance for industry and FDA staff, November 2013. FDA docket FDA-2011-D-0305
  4. 21 CFR 314.1, Scope of this part (applications for FDA approval to market a new drug; current edition). 21 CFR 314.1