ICH Q2(R1)

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.

Bauhinia variegata Linn. (Fabaceae) is a widely used medicinal plant whose bark exhibits antioxidant, anti-inflammatory, antimicrobial, hepatoprotective, and anticancer activities, largely attributed to its flavonoid content, of which quercetin is a key bioactive marker. Since no validated method previously existed for quantifying quercetin specifically in B. variegata bark, the present study aimed to develop and validate a simple, sensitive, and reproducible HPTLC method for this purpose, in accordance with ICH Q2(R1) guidelines. Chromatographic separation was achieved on silica gel 60 F₂₅₄ plates using a mobile phase of ethyl acetate: toluene: methanol: formic acid (3.5: 6: 0.5: 0.5, v/v/v/v), with densitometric detection at 383 nm, giving a well-resolved band at Rf 0.54. The method showed good linearity over 100–700 ng/band (y = 23.063x − 430.75, R² = 0.991), with an LOD of 20 ng/band and LOQ of 80 ng/band. Precision (%RSD < 2% for repeatability, intraday, and interday studies), accuracy (mean recovery 98.57–100.65%), robustness, and specificity all met acceptance criteria, confirming the reliability of the method. Application to the methanolic bark extract of B. variegata revealed a quercetin content of 0.012% w/w, with consistent results across replicate analyses. This validated HPTLC method offers a rapid, cost-effective, and reliable tool for the routine quality control, standardization, and phytochemical evaluation of B. variegata bark and its extracts. Keywords: Quercetin; HPTLC; Bauhinia variegata; method validation; ICH Q2(R1); phytochemical standardization