Quinethazone is a synthetic thiazide-like diuretic and antihypertensive active pharmaceutical ingredient. It belongs to the quinazoline/sulfonamide class and acts primarily by reducing sodium and chloride reabsorption in the distal convoluted tubule of the kidney. Quinethazone is identified by CAS 73-49-4, molecular formula C₁₀H₁₂ClN₃O₃S, and molecular weight 289.74 g/mol.
Quinethazone is chemically identified as 7-chloro-2-ethyl-4-oxo-2,3-dihydro-1H-quinazoline-6-sulfonamide. It is also known by names including Quinethazon, Quinethazonum and historically by the brand name Hydromox. FDA GSRS assigns the substance UNII 455E0S048W.
The API is generally described as a white to yellowish-white crystalline powder or fibrous crystals. It has a reported melting range around 250–252°C and is poorly soluble in water.
| Parameter | Details |
|---|---|
| Product Name | Quinethazone |
| CAS Number | 73-49-4 |
| Molecular Formula | C₁₀H₁₂ClN₃O₃S |
| Molecular Weight | 289.74 g/mol |
| Exact Mass | 289.0287901 Da |
| FDA UNII | 455E0S048W |
| ChEBI | CHEBI:8717 |
| ChEMBL | CHEMBL1532 |
| DrugBank | DB01325 |
| ATC Code | C03BA02 |
| Chemical Class | Quinazoline sulfonamide |
| Pharmacological Class | Thiazide-like diuretic |
| Therapeutic Area | Cardiovascular / Hypertension |
| Appearance | White to yellowish-white crystalline powder |
The formula, CAS, molecular weight, UNII and pharmacological classification are supported by PubChem's current record.
Quinethazone is a thiazide-like diuretic historically used in the management of hypertension. It inhibits sodium/chloride reabsorption in the distal renal tubule, increasing urinary excretion of sodium, chloride and water.
Pharmaceutical applications include:
Quinethazone can be characterized by HPLC, H-NMR, LC-MS, IR and HPLC-ESI-MS. A published commercial API specification reports assay 99.0–101.0% on an anhydrous basis, purity ≥99.0%, LOD ≤2.0%, water ≤1.0%, heavy metals ≤10 ppm, residue on ignition ≤0.1%, sulfated ash ≤0.5%, unspecified individual impurities ≤0.10% each, and total impurities ≤0.50%.
These numerical values are useful for CMS reference but should be described as a commercial/API specification, rather than presented as a universally applicable pharmacopoeial monograph.
Quinethazone API manufacturing requires controlled synthesis and purification to achieve consistent chemical identity, assay, related-substance profile and physical characteristics.
Quality control should include chromatographic purity testing, structural confirmation, residual solvent assessment, water determination, elemental impurity control and appropriate physical-property testing.
Quinethazone should be protected from strong light and stored in tightly closed, moisture-protective containers under controlled conditions.
Commercial specifications recommend well-closed, light-resistant and airtight containers.
Typical Quinethazone API documentation may include:
A reliable Quinethazone API manufacturing program should provide consistent assay, controlled related substances, validated analytical testing and complete batch documentation. The API should be manufactured under appropriate pharmaceutical quality systems with suitable controls for moisture, light, impurities and physical characteristics.
| Parameter | Specification |
|---|---|
| Appearance | white to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 99.0–101.0% |
| Loss on Drying | NMT 2.0% |
| Residue on Ignition | NMT 0.10% |
| Heavy Metals | NMT 10 ppm |
| Individual Impurity | NMT 0.10% |
| Total Impurities | NMT 0.50% |
| Water Content | NMT 1.0% |