Integration of Green Analytical Chemistry and Quality by Design Approach for Systematic Development of Stability-Indicating RP-HPLC Method for Estimation of Guanfacine

Background: Guanfacine, a phenylacetyl-guanidine derivative, has gained pharmaceutical significance due to its therapeutic applications. A stability-indicating, Quality by Design (QbD)- based RP-HPLC method was developed and validated for its quantification in bulk drugs to meet its growing demand. Additionally, its environmental sustainability was assessed using the AGREE tool to ensure compliance with Green Analytical Chemistry (GAC) principles. Materials and Methods: The RP-HPLC method was optimized using Box-Behnken Design (BBD) with a C-18 column and a mobile phase of methanol and 0.1% ortho-phosphoric acid (60:40 v/v). Key parameters such as specificity, linearity, precision, accuracy, robustness, and ruggedness were evaluated as per ICH guidelines. Stability-indicating capability was confirmed through forced degradation studies under acidic, basic, oxidative, and neutral conditions. The AGREE tool was applied to assess the method’s greenness. Results: The method exhibited a retention time of 3.96 min, peak area of 2613, tailing factor of 0.18, and 4055.83 theoretical plates. Sensitivity analysis yielded LOD of 0.39 μg/mL and LOQ of 1.19 μg/mL. Precision studies showed %RSD below 0.5%, and linearity was confirmed with R²=0.9998. The AGREE score of 0.69 indicated moderate greenness, with potential for further improvement. Conclusion: The QbD-driven RP-HPLC method was successfully developed, validated, and assessed for environmental sustainability, demonstrating high precision, accuracy, and stability-indicating capability. Future refinements, such as solvent reduction and greener alternatives, could further enhance sustainability in pharmaceutical analysis.