Development and Comprehensive Validation of A Stability-Indicating UPLC Method For the Simultaneous Estimation of Sulfamethoxazole and Clindamycin In Combined Pharmaceutical Dosage Form

To develop and validate a rapid, precise, and stability-indicating UPLC method for the simultaneous estimation of Sulfamethoxazole and Clindamycin in combined pharmaceutical dosage form, in accordance with ICH Q2 (R1) guidelines 5. A simple, precise, and robust UPLC method was developed and validated for the simultaneous estimation of Sulfamethoxazole and Clindamycin in a fixed-dose pharmaceutical formulation 1–3. The method was developed on a reverse-phase C18 column using a mobile phase of methanol and water. Detection was carried out at 254?nm. Validation followed ICH Q2 (R1) guidelines, including accuracy, precision, linearity, robustness, ruggedness, and sensitivity 4–6. Linearity was observed over the range of 10–200 μg/mL for both drugs (R² > 0.998). %Recovery was within 98–102% with % RSD < 0.5%. LOD and LOQ were 0.195 μg/mL and 0.592 μg/mL, respectively. The method was unaffected by small deliberate changes in analytical conditions. The validated method is stability-indicating, highly sensitive, and suitable for routine analysis and quality control of Sulfamethoxazole and Clindamycin in combined dosage form.