Planer chromatographic method development and validation of Tadalafil and Mirabegron using fractional factorial design approach

The present research focuses on developing a high-performance thin-layer chromatographic (HPTLC) method using a design of experiment approach for simultaneously estimating Tadalafil and Mirabegron. Chromatographic separation was achieved on aluminum plates precoated with silica gel 60 F254 using an optimized mobile phase of MeOH: ACN: n-Butanol: TEA (6:2:2:0.1%v/v/v/v). A fractional factorial design was applied for the robustness study and the independent variables selected were chamber saturation time (A), wavelength (B), mobile phase composition (C) and solvent front (D). It was statistically revealed that the volume of MeOH affected the Rf of both drugs resulting in stricter control of MeOH volume compared to the other three variables. Rf for Tadalafil and Mirabegron was 0.75 and 0.45 at 242 nm. Calibration plots were linear for Tadalafil (100–300 ng/band) and Mirabegron (500–1500 ng/band), with recovery rates of 98.15%–100.34% and 98.46%–102.14%, respectively. The method was validated per ICH Q2(R1) guidelines, demonstrating linearity, precision, accuracy and selectivity, with %RSD values below 2% for both drugs. This HPTLC method is simple, accurate, reproducible and suitable for routine quality control of pharmaceutical formulations.