No proprietary name confusable with another drug's name

AI-verifiedwarningBinding lawRaised as a question — a person decides

Rule

A drug or ingredient may not be advertised under a proprietary name that could be confused, by spelling or pronunciation, with another drug's or ingredient's proprietary or established name.

Check

Compare the proprietary name used to other marketed drug/ingredient names for confusing similarity.

Escalate when

Similarity is arguable and requires assessment of likely confusion.

Where this comes from

21 CFR 202.1(a)(5). The highlighted words are quoted exactly; a script confirms they appear in the source before the rule can be published.

…rug or ingredient has some unique effectiveness or composition, when, in fact, the drug or ingredient is a common substance, the limitations of which are readily recognized when the drug or ingredient is listed by its established name. (4) The advertisement shall not feature inert or inactive ingredients in a manner that creates an impression of value greater than their true functional role in the formulation. (5) The advertisement shall not designate a drug or ingredient by a proprietary name that, because of similarity in spelling or pronunciation, may be confused with the proprietary name or the established name of a different drug or ingredient. (b)(1) If an advertisement for a prescription drug bears a proprietary name or designation for the drug or any ingredient thereof, the established name, if such there be, corresponding to such proprietary name or designation shall accompany such proprietary name or designation each time it is featured in the advertisement for the drug; but, except as provided below in this subparagraph, the established name need no…

Open the original at these words on ecfr.gov ↗Read our full copy →

Document: 21 CFR 202.1
Version: 2026-09-16 — the link above is pinned to this date, so it shows the text as it stood then
Retrieved: 2026-09-21 from www.ecfr.gov
Fingerprint: a542640a872b3f2702d549e8…

Applies when

Naturepromotional

How this rule was checked

Citation proven by script and passed an independent verifier running on a different model. Not yet confirmed by a human.

Drafted
claude-sonnet-5 · 2026-09-21
Independent verification — pass
claude-opus-5 · 2026-09-21
Reviewer's reasons
- The quote is a verbatim operative prohibition from 21 CFR 202.1(a)(5) ('The advertisement shall not designate...'), not drawn from a definition, example, or description of what is not required; the rule statement follows directly from it.
- The rule preserves both limbs of the source's comparison set (confusion with either the proprietary name or the established name of a different drug or ingredient) and both routes (spelling or pronunciation).
- Not overstated: 'shall not' is rendered as a prohibition without hardening the source's 'may be confused' threshold into 'is confusing'; the rule statement is anchored to advertising, matching 202.1's scope for prescription-drug advertisements, so applies_when 'promotional' neither invents nor drops a limit. The check's 'other marketed drug/ingredient names' is marginally narrower than the source's 'a different drug or ingredient', which is a permissible operational narrowing.
- Atomic: a single obligation with a single finding; 'spelling or pronunciation' are alternative routes to the same confusing-similarity determination, not separately checkable requirements.
- Determinism correctly set to judgment: 'may be confused' turns on likelihood of confusion and cannot be settled by presence/absence or literal match; the escalation condition correctly targets arguable similarity.
- Authority correctly binding: 21 CFR 202.1 is a codified regulation.
- Locator 21 CFR 202.1(a)(5) matches the paragraph in which the quoted sentence appears in the source text.
- Severity 'warning' is defensible: the provision is binding, but no violation can be established without a comparative likelihood-of-confusion assessment, so reviewer flagging rather than hard failure is consistent with the judgment determinism.