Why does CAS 38304-91-5 appear in more than one EU cosmetic annex?

A substance identified by CAS 38304-91-5 may appear in multiple EU cosmetic regulation annexes when it is subject to different conditions in different contexts — for example, restricted under Annex III with specific conditions, while also appearing in Annex IV as an approved colorant under separate entry conditions. Each entry must be reviewed individually.

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Use the INCI Checker on CosIng Checker with INCI names, CAS numbers or EC numbers. Paste CAS 38304-91-5 to screen it directly, then review every linked annex record and supplier document.

CAS 1 record

CAS 38304-91-5

Q: How do I use CAS 38304-91-5 for compliance screening?

Cross-reference CAS 38304-91-5 against your raw material specification sheets and CoA documents. When it appears in Annex II, verify absence. When it appears in Annex III, verify that concentration limits and product type conditions are met. All annex entries sharing this CAS number are listed on this page.

CAS 38304-91-5 matches 1 EU annex record across Annex II–VI of Regulation 1223/2009.

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Chemical identity and properties

PubChem 2D chemical structure for CAS 38304-91-5

CAS 38304-91-5PubChem CID 4201

Minoxidil

Minoxidil is a pyrimidine N-oxide that is pyrimidine-2,4-diamine 3-oxide substituted by a piperidin-1-yl group at position 6. It has a role as a vasodilator agent and an antihypertensive agent. It is a member of piperidines, an aminopyrimidine and a pyrimidine N-oxide. — ChEBI

IUPAC name: 3-hydroxy-2-imino-6-piperidin-1-ylpyrimidin-4-amine

Molecular formula: C9H15N5O
Molecular weight: 209.25 g/mol
Exact mass: 209.12766012 Da
XLogP3: 1.2
Topological polar surface area: 88.9 Å²
Hydrogen-bond donors: 3
Hydrogen-bond acceptors: 3
Covalent units: 1
Defined stereocentres: 0

Also known as

LonitenRogaineMinoximenTheroxidilAlopexilAlostilTricoxidilLonolox

16 more reported names

RegaineNormoxidilPrexidilMinodylPierminox2,6-Diamino-4-(piperidin-1-yl)pyrimidine 1-oxideRiUPMintopU-108582,4-Pyrimidinediamine, 6-(1-piperidinyl)-, 3-oxideU-10,8586-Amino-1,2-dihydro-1-hydroxy-2-imino-4-piperidinopyrimidineNSC-7571066-(1-piperidinyl)-2,4-pyrimidinediamine-3-oxide3-hydroxy-2-imino-6-(1-piperidyl)pyrimidin-4-amineCHEBI:6942

Open full PubChem record PubChem annotations 3D structure image

External database identifiers

ChEBI:CHEBI:6942
ChEBI:CHEBI:92128
ChEMBL:CHEMBL1372483
ChEMBL:CHEMBL609587
ChEMBL:CHEMBL802
EPA DTXSID:DTXSID301372970
EPA DTXSID:DTXSID9040685
PubMed:29968805
PubMed:22363845
PubMed:22077158
PubMed:17761356
PubMed:16253450
PubMed:16043173
PubMed:15922339
PubMed:4647

Retrieved from NIH PubChem on 2026-09-02 by checksum-valid CAS matching. Chemical properties do not replace the regulatory decision on this page.

Records for CAS 38304-91-5

1 total

Annex

Entry

372

6-(Piperidinyl)-2,4-pyrimidinediamine-3-oxide (Minoxidil (INN)) and its salts

253-874-2

How CAS 38304-91-5 is used on this site

CAS 38304-91-5 is the Chemical Abstracts Service identifier used to pin this page to a specific substance. In the current dataset, 1 EU annex record shares this identifier, which helps you cross-check whether the same substance appears under one regulatory context or several.

Use this page when a supplier specification, SDS or raw-material dossier gives you CAS 38304-91-5 and you need to see every linked Annex II–VI record in one place. The entry cards above are the quickest route to concentration limits, warnings, annex placement and product-type conditions.

Frequently asked questions

A substance identified by CAS 38304-91-5 may appear in multiple EU cosmetic regulation annexes when it is subject to different conditions in different contexts. For example, a substance might be restricted under Annex III with specific conditions, and the same CAS might also appear in Annex IV as an approved colorant under separate entry conditions. Each entry must be reviewed individually.

Cross-reference the CAS number against your raw material specification sheets and CoA documents. When a CAS appears in Annex II, verify absence. When it appears in Annex III, verify that concentration limits and product type conditions are met in your formulation. All annex entries sharing this CAS number are listed above.

A CAS number is assigned by the Chemical Abstracts Service (USA) and is globally recognised. An EC number is a European Commission identifier from inventories such as EINECS, ELINCS or the NLP list. Both identifiers may appear in EU cosmetic annex entries. Some substances have both, some have only one, and some older entries may have neither.

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