Sulfadimethoxine API is a long-acting sulfonamide antibacterial active pharmaceutical ingredient. It is chemically identified as 4-amino-N-(2,6-dimethoxy-4-pyrimidinyl)benzenesulfonamide, with molecular formula C₁₂H₁₄N₄O₄S, molecular weight 310.33 g/mol, and CAS Number 122-11-2.
Sulfadimethoxine belongs to the sulfonamide class of antibacterial compounds and inhibits bacterial folate synthesis through inhibition of dihydropteroate synthase, an enzyme involved in the biosynthesis of dihydrofolic acid.
Sulfadimethoxine is a crystalline sulfonamide compound containing a substituted pyrimidine ring and a benzenesulfonamide moiety. It is generally described as a white to off-white crystalline powder. The reported melting range is approximately 197–203°C, while the USP monograph specifies 197–202°C.
The API is practically insoluble in water and has greater solubility under alkaline conditions. Published reference data report water solubility around 343 mg/L under specified experimental conditions, while USP describes it as practically insoluble in water and soluble in 2 N sodium hydroxide.
Sulfadimethoxine is a sulfonamide antibacterial API used primarily in veterinary pharmaceutical applications. It has activity against susceptible Gram-positive and Gram-negative organisms and has historically been used in veterinary preparations for respiratory, urinary, enteric and soft-tissue infections.
Sulfadimethoxine is also used in combination veterinary formulations with other antibacterial agents, including potentiating compounds such as trimethoprim or ormetoprim.
Sulfadimethoxine inhibits dihydropteroate synthase, interfering with bacterial folate synthesis. This reduces the availability of folate intermediates required for nucleic-acid and other essential cellular processes.
Sulfadimethoxine has a USP drug-substance monograph with established requirements for identification, assay, loss on drying, residue on ignition and heavy metals. USP specifies an assay of 98.0–102.0% on the dried basis.
The USP HPLC assay uses a 254-nm detector, with a phosphate/methanol mobile phase and an L1 chromatographic column. System suitability includes a tailing factor of NMT 1.5 and relative standard deviation of NMT 1.0%.
Swapnroop Drugs and Pharmaceuticals provides pharmaceutical API manufacturing capabilities supported by controlled processing, analytical testing and quality documentation.
Sulfadimethoxine API can be evaluated according to applicable USP requirements and customer-specific specifications, with analytical control of assay, moisture-related loss, inorganic residue and elemental impurities.
Sulfadimethoxine should be maintained in tight, light-resistant containers under controlled storage conditions. Appropriate packaging should protect the API from excessive moisture, light and contamination.
Depending on applicable requirements, documentation may include:
Sulfadimethoxine has established pharmacopeial quality requirements and requires controlled analytical testing for assay and physicochemical characteristics. Swapnroop focuses on pharmaceutical API manufacturing, quality evaluation and documentation support for Sulfadimethoxine and other specialized APIs.
| 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% |
| Heavy Metals | NMT 20 ppm |
| Melting Point | 197–202°C |