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Pharmaceutical impurity

Metamizole Sodium Monohydrate Imp. A (EP): 4-Formylamino-1,5-dimethyl- 2-phenyl-1,2-dihydro-3H-pyrazol-3-one (4-Formylaminophenazone)

Metamizole Sodium Monohydrate Imp. A (EP): 4-Formylamino-1,5-dimethyl- 2-phenyl-1,2-dihydro-3H-pyrazol-3-one (4-Formylaminophenazone) is listed in the pharmaceutical impurity collection under CAS 1672-58-8. Its represented structure has formula C12H13N3O2 and a calculated molecular weight of 231.25 g/mol.

2D chemical structure

N H O O N N

Chemical identity

Catalog name
Metamizole Sodium Monohydrate Imp. A (EP): 4-Formylamino-1,5-dimethyl- 2-phenyl-1,2-dihydro-3H-pyrazol-3-one (4-Formylaminophenazone)
Common name
Metamizole Sodium Monohydrate Imp. A (EP)
Chemical name
4-Formylamino-1,5-dimethyl- 2-phenyl-1,2-dihydro-3H-pyrazol-3-one (4-Formylaminophenazone)
CAS
1672-58-8
SMILES
Cc1c(NC=O)c(=O)n(-c2ccccc2)n1C
InChI
InChI=1S/C12H13N3O2/c1-9-11(13-8-16)12(17)15(14(9)2)10-6-4-3-5-7-10/h3-8H,1-2H3,(H,13,16)
InChIKey
WSJBSKRPKADYRQ-UHFFFAOYSA-N
Associated API
Metamizole Sodium Monohydrate

Record ID: A633241e8cb83

Computed properties

C12H13N3O2 Molecular formula
231.255 g/molMolecular weight
231.1008 DaMonoisotopic exact mass
56.03 ŲTopological polar surface area
1.0527 Calculated LogP (Wildman–Crippen)
65.4337 cm³/molMolar refractivity (Wildman–Crippen)
2 countHydrogen-bond acceptors
1 countHydrogen-bond donors

Descriptors are calculated from the displayed SMILES. Calculated LogP is not a measured partition coefficient or a pH-specific LogD.

Molecular descriptor profile

Descriptor radar

Mol. weight LogP TPSA HBA HBD Rotatable 25 50 75 100

Structural feature counts

0 1 2 3 Count H-bond acceptors H-bond donors Rotatable bonds Rings Aromatic rings Stereo centers

Element composition

C H N O 0 3 6 9 12 Number of atoms

Radar scale: 0–100 percentile within 25,771 distinct represented structures in this release, using the midpoint rank for ties. Larger values indicate a higher descriptor rank, not greater safety or toxicity. Element counts include hydrogen and combine isotopes under each element.

Radar values and percentile reference
DescriptorValuePercentile
Molecular weight231.25525.39
Calculated LogP (Wildman–Crippen)1.052726.06
Topological polar surface area56.0337.02
Hydrogen-bond acceptors215.92
Hydrogen-bond donors138.08
Rotatable bonds (strict)337.08

Complete molecular descriptors

PropertyCalculated valueUnit / type
Molecular formulaC12H13N3O2dimensionless
Molecular weight231.255g/mol
Monoisotopic exact mass231.1008Da
Topological polar surface area56.03Ų
Calculated LogP (Wildman–Crippen)1.0527dimensionless
Molar refractivity (Wildman–Crippen)65.4337cm³/mol
Hydrogen-bond acceptors2count
Hydrogen-bond donors1count
Rotatable bonds (strict)3count
Heavy atoms17count
Heteroatoms5count
Rings2count
Aromatic rings2count
Aliphatic rings0count
Saturated rings0count
Aromatic heterocycles1count
Aliphatic heterocycles0count
Saturated heterocycles0count
Aromatic carbocycles1count
Aliphatic carbocycles0count
Fraction of sp³ carbon atoms0.1667fraction
Formal charge0e
Disconnected components1count
Isotopically specified atoms0count
Potential atom stereocenters0count
Unspecified atom stereocenters0count
Spiro atoms0count
Bridgehead atoms0count
Labute approximate surface area98.2734Ų
Valence electrons88count
Radical electrons0count
Bertz complexity596.2036index
Balaban J2.6792index

Ring categories overlap and should not be summed. No toxicity result, PDE, HBEL or acceptable intake is inferred from these descriptors.

Toxicological services and resources for Metamizole Sodium Monohydrate Imp. A (EP): 4-Formylamino-1,5-dimethyl- 2-phenyl-1,2-dihydro-3H-pyrazol-3-one (4-Formylaminophenazone)

Qualification and safety assessment of Metamizole Sodium Monohydrate Imp. A (EP): 4-Formylamino-1,5-dimethyl- 2-phenyl-1,2-dihydro-3H-pyrazol-3-one (4-Formylaminophenazone)

Explore toxicological qualification of Metamizole Sodium Monohydrate Imp. A (EP): 4-Formylamino-1,5-dimethyl- 2-phenyl-1,2-dihydro-3H-pyrazol-3-one (4-Formylaminophenazone) and ICH M7 mutagenic impurity assessment of Metamizole Sodium Monohydrate Imp. A (EP): 4-Formylamino-1,5-dimethyl- 2-phenyl-1,2-dihydro-3H-pyrazol-3-one (4-Formylaminophenazone) for evaluation of this impurity in its pharmaceutical context.

Where data gaps need to be addressed, resources include read-across assessment for Metamizole Sodium Monohydrate Imp. A (EP): 4-Formylamino-1,5-dimethyl- 2-phenyl-1,2-dihydro-3H-pyrazol-3-one (4-Formylaminophenazone) and acceptable intake and limit justification for Metamizole Sodium Monohydrate Imp. A (EP): 4-Formylamino-1,5-dimethyl- 2-phenyl-1,2-dihydro-3H-pyrazol-3-one (4-Formylaminophenazone). The relevant approach depends on the available evidence, exposure and duration of use.

Related Altox services and technical resources

Other catalogue designations with the same represented structure

These are separate catalogue entries; shared structure does not establish interchangeable pharmacopoeial designations.

Identity sources and calculation method

Identifiers originate from the source catalogues and available public identity records. InChI and InChIKey on this page are generated from the displayed SMILES. RDKit validation checks the molecular representation; it does not independently verify every catalogue assignment.

Discuss an assessment for Metamizole Sodium Monohydrate Imp. A (EP): 4-Formylamino-1,5-dimethyl- 2-phenyl-1,2-dihydro-3H-pyrazol-3-one (4-Formylaminophenazone)

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