Sulfadoxine is recognized in several major pharmacopoeias, including the United States Pharmacopeia (USP), British Pharmacopoeia (BP), European Pharmacopoeia (EP), and Indian Pharmacopoeia (IP). The USP monograph specifies that Sulfadoxine should contain not less than 99.0% and not more than 101.0% of C₁₂H₁₄N₄O₄S, calculated on the dried basis. Identification tests include infrared absorption and ultraviolet absorption methods. The melting range is specified between 197°C and 200°C. Loss on drying should not exceed 0.5%, and residue on ignition is limited to 0.1%. Heavy metals are restricted to 0.002%. Chromatographic purity tests ensure that no impurity exceeds the size and intensity of the principal spot obtained from the standard solution. The assay is conducted using a nitrite titration method, with each mL of 0.1 M sodium nitrite equivalent to 31.03 mg of Sulfadoxine.
Dissolution testing is a critical quality control measure for Sulfadoxine tablets. While specific dissolution parameters for Sulfadoxine are not detailed in the provided sources, general dissolution tests for tablets are outlined in pharmacopoeial general chapters. For instance, the USP general chapter <711> on dissolution provides guidelines on apparatus, media, and procedures to ensure consistent drug release profiles.
Stability testing for Sulfadoxine should adhere to the International Council for Harmonisation (ICH) guidelines, which define stability testing conditions based on climatic zones. For example, ICH Zone IV, which includes hot and humid climates, recommends testing at 30°C ± 2°C and 75% ± 5% relative humidity. These conditions help ensure that Sulfadoxine maintains its quality, safety, and efficacy throughout its shelf life.
