Chemical substance record

Primidone

125-33-7C₁₂H₁₄N₂O₂218.256 g/mol

Organic/Inorganic Small MoleculeChEBI source record

A pyrimidone that is dihydropyrimidine-4,6(1H,5H)-dione substituted by an ethyl and a phenyl group at position 5. It is used as an anticonvulsant for treatment of various types of seizures. — ChEBI

Safety references

Safety documents & references

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Identity & molecular properties

Source-linked values

CAS number	125-33-7	ChEBI ↗
Molecular formula	C₁₂H₁₄N₂O₂	ChEBI ↗
Molar mass	218.256 g/mol	ChEBI ↗
Monoisotopic mass	218.10553 Da	ChEBI ↗
Formal charge	0	ChEBI ↗
ChEBI identifier	CHEBI:8412	ChEBI ↗

Cross-source molecular data

PubChem

Molar mass	218.25 g/mol	PubChem ↗
Exact mass	218.105527694 Da	PubChem ↗
Computed XLogP	0.9	PubChem ↗
Topological polar surface area (Å²)	58.2	PubChem ↗
H-bond donors	2	PubChem ↗
H-bond acceptors	2	PubChem ↗
Rotatable bonds	2	PubChem ↗

PubChem computed values are shown separately from the ChEBI record. An exact InChIKey match was used to connect the records. Molecular descriptors do not describe a supplied product’s purity, particle size or performance.

Names & structural identifiers

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Source preferred name

primidone

IUPAC name

5-ethyl-5-phenyldihydropyrimidine-4,6(1H,5H)-dione

InChIKey

DQMZLTXERSFNPB-UHFFFAOYSA-N

SMILES

CCC1(c2ccccc2)C(=O)NCNC1=O

InChI

InChI=1S/C12H14N2O2/c1-2-12(9-6-4-3-5-7-9)10(15)13-8-14-11(12)16/h3-7H,2,8H2,1H3,(H,13,15)(H,14,16)

Names & synonyms

5-ethyl-5-phenyldihydropyrimidine-4,6(1H,5H)-dioneprimidonaprimidonum

Names are supplied by ChEBI. Trade names and related synonyms may describe a broader product context.

Classification & relationships

ChEBI ontology

pyrimidoneChEBI parent class · 38337 ↗

organic heterocyclic compound organic molecular entity

Roles recorded in ChEBI

anticonvulsantxenobioticenvironmental contaminant

Database role annotations describe reported biological or chemical roles; they are not product approvals or recommendations for use.

Mass ↔ amount of substance

Calculated from sourced mass

Amount

Input unit

Equivalent amount

0.00458178 mol

Uses 218.256 g/mol from ChEBI. Assumes the substance described by this record; no purity or concentration correction is applied.

Elemental composition

Theoretical mass fractions

C

Carbon · 12 atoms

66.04%

O

Oxygen · 2 atoms

14.66%

N

Nitrogen · 2 atoms

12.84%

H

Hydrogen · 14 atoms

6.47%

Calculated theoretical mass fractions from the reported formula and PubChem periodic-table atomic masses. These are not assay or purity results.

Research & patent references

Selected source associations

Blood and cerebrospinal fluid pharmacokinetics of primidone and its primary pharmacologically active metabolites, phenobarbital and phenylethylmalonamide in the rat. ↗European journal of drug metabolism and pharmacokinetics · 1999 Jul-Sep · PMID 10716065

Therapeutic monitoring of antiepileptic drugs for epilepsy. ↗The Cochrane database of systematic reviews · 2007 Jan 24 · PMID 17253477

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Sources & record history

Checked 27 Sep 2026

Identity, formula, mass, synonyms & ontologyEMBL-EBI ChEBI · CHEBI:8412

Release 255, 9 September 2026. ChEBI three-star (manually annotated) source entry. View original record ↗ · CC BY 4.0

Additional molecular descriptorsNCBI PubChem · CID 4909 · retrieved 2026-09-27

PubCAS formats source data, connects references and computes explicitly labelled conversions. CAS cross-references are supplied by ChEBI; they do not constitute CAS verification or endorsement.

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