Quetiapine Fumarate is the fumarate salt of quetiapine and an established pharmaceutical active ingredient belonging to the dibenzothiazepine class of atypical antipsychotic agents. The pharmaceutical salt is technically a hemifumarate, consisting of two quetiapine molecules associated with one molecule of fumaric acid. Its CAS Number is 111974-72-2, molecular formula is C₄₆H₅₄N₆O₈S₂, and molecular weight is 883.1 g/mol.
Quetiapine Fumarate is recognized in major pharmacopoeial standards. The current USP 2025 monograph defines the substance as containing 98.0–102.0% quetiapine fumarate on the dried basis. The BP 2025 monograph provides a tighter content range of 99.0–101.0% on the dried substance, together with a fumaric acid content requirement of 12.5–13.8%.
Product Name: Quetiapine Fumarate
Synonyms: Quetiapine Hemifumarate, Quetiapine Fumarate
CAS Number: 111974-72-2
Molecular Formula: C₄₆H₅₄N₆O₈S₂
Molecular Weight: 883.1 g/mol
Salt Ratio: 2:1 Quetiapine Acid
Chemical Class: Dibenzothiazepine derivative
Therapeutic Class: Atypical antipsychotic
Appearance: White or almost white crystalline powder
API Form: Fumarate / hemifumarate salt
The official Canadian product information describes Quetiapine Fumarate as a white or almost white crystalline powder. It is practically insoluble in water, freely soluble in glacial acetic acid, and sparingly soluble in methanol and ethanol.
Japanese Pharmacopoeia information similarly describes Quetiapine Fumarate as a white powder that is sparingly soluble in methanol and slightly soluble in water and ethanol.
Quetiapine is a second-generation atypical antipsychotic with activity involving several neurotransmitter receptor systems. PubChem identifies quetiapine as a dibenzothiazepine derivative and records activity involving dopamine, serotonin, histamine and adrenergic receptors.
Quetiapine Fumarate is used because the fumarate salt provides a defined pharmaceutical form suitable for formulation into oral dosage forms. The drug substance exhibits polymorphism, which is an important consideration during pharmaceutical manufacturing and solid-state characterization. BP 2025 specifically notes that Quetiapine Fumarate shows polymorphism.
The API is characterized using orthogonal analytical techniques including infrared identification, liquid chromatographic assay and related-substance testing. These controls help establish identity, potency, purity and consistency between manufacturing batches.
Quetiapine Fumarate is used as the active pharmaceutical ingredient in formulations for the treatment of schizophrenia and bipolar disorder. Official product labeling identifies quetiapine as an atypical antipsychotic belonging to the dibenzothiazepine derivative class.
Quetiapine-containing pharmaceutical products are available in immediate-release and extended-release tablet formulations. Depending on the approved product and indication, quetiapine is used in the management of schizophrenia, manic episodes associated with bipolar disorder, depressive episodes associated with bipolar disorder and, in specific approved formulations, as adjunctive therapy for major depressive disorder.
For API manufacturers and formulation developers, maintaining control of polymorphic form, chemical purity, assay, moisture and related substances is particularly important because these attributes can influence pharmaceutical processing and product performance.
Quetiapine Fumarate has comprehensive current pharmacopoeial quality requirements.
USP 2025 specifies 98.0–102.0% assay on the dried basis. The USP assay is performed by liquid chromatography with UV detection at 230 nm. The USP method uses a methanol/acetonitrile/buffer mobile phase and controls chromatographic system suitability through resolution, tailing factor and relative standard deviation requirements.
USP specifies Residue on Ignition NMT 0.1% and Loss on Drying NMT 0.5%, with the latter determined by drying at 105°C to constant weight.
The current USP organic-impurity specification includes Quetiapine Quaternary Salt, Quetiapine Related Compound G, Quetiapine Related Compound B, Quetiapine Desethoxy, Quetiapine Tetraethylene Glycol Analog, N-Ethyl Quetiapine and Bis(dibenzothiazepinyl)piperazine. The specified individual limits range from 0.10–0.15%, with any other unknown individual impurity NMT 0.10% and total impurities NMT 0.50%. Peaks below 0.05% are disregarded.
BP 2025 specifies impurities G and N at NMT 0.15% each, unspecified impurities at NMT 0.10% each, total impurities NMT 0.5%, and a reporting threshold of 0.05%. BP also specifies sulfated ash NMT 0.1%.
Quetiapine Fumarate manufacturing requires controlled chemical processing and rigorous analytical testing to maintain consistent pharmaceutical quality. Important manufacturing considerations include raw-material control, reaction-process monitoring, salt formation, crystallization, drying, particle characteristics and polymorphic-form control.
Because Quetiapine Fumarate exhibits polymorphism, appropriate solid-state characterization is important during manufacturing and quality control. Batch testing can include infrared identification, HPLC assay, related-substance analysis, loss on drying, residue on ignition and other applicable physical and chemical tests.
Specifications can be aligned with USP, BP/Ph. Eur., JP or approved customer requirements depending on the intended regulatory market.
Quetiapine Fumarate should be protected from light and stored in suitable well-closed containers. The current USP monograph specifies preservation in well-closed containers, protected from light.
Controlled packaging and storage help protect the API from environmental exposure and support maintenance of its chemical and physical characteristics throughout storage and transportation.
Typical documentation for Quetiapine Fumarate API may include:
Quetiapine Fumarate is a well-established pharmaceutical API with current USP and BP monographs providing defined numerical requirements for assay, related substances, moisture and inorganic residue.
The current USP standard provides an assay range of 98.0–102.0%, while BP provides 99.0–101.0% on the dried substance. Both standards provide comprehensive controls for related substances, supporting consistent API quality for pharmaceutical formulation.
Its established pharmaceutical applications, defined hemifumarate salt structure and comprehensive pharmacopoeial quality requirements make Quetiapine Fumarate suitable for pharmaceutical manufacturing and formulation development.
| Parameter | Specification |
|---|---|
| Appearance | white to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 98.0% – 102.0% |
| Loss on Drying | NMT 0.5% |
| Residue on Ignition | NMT 0.1% |
| Individual Impurity | NMT 0.10% |
| Total Impurities | NMT 0.50% |