DoE-assisted RP-HPLC Method Development for the Estimation of Flurbiprofen in Nanostructured Lipid Carriers and Pharmaceutical Dosage Forms

Flurbiprofen is a non-steroidal anti-inflammatory drug (NSAID) with anti-inflammatory, antipyretic, and analgesic properties. NSAIDs are commonly used to treat conditions such as gout, arthritis, muscle pain, pyrexia, dysmenorrhea, and migraines; however, their toxicity may lead to hepatotoxicity, renal damage, and hypertension. In this study, a reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed using a central composite design (CCD). The developed method was validated for linearity, robustness, limit of detection (LOD), limit of quantification (LOQ), precision, and accuracy, and was also applied to analyze flurbiprofen nanostructured lipid carriers (NLCs) and marketed formulations, including topical gel and eye drops. The calibration curve for flurbiprofen was linear over the concentration range of 0.125–50 µg/mL. The percentage recovery at sample concentrations of 400, 500, and 600 ng was 97.79%, 100.26%, and 100.61%, respectively, indicating good accuracy. The percentage relative standard deviation (%RSD) was less than 2%, confirming the precision of the method. Robustness was demonstrated by %RSD values below 2% following deliberate variations in flow rate, injection volume, and mobile phase pH. The LOD and LOQ were determined to be 50 ng/mL and 125 ng/mL, respectively. Using the optimized method, flurbiprofen was successfully identified and quantified in NLCs as well as in marketed topical gel and eye drop formulations, producing well-resolved peaks with high accuracy, precision, and sensitivity. Comprehensive testing and validation confirmed that the developed method is suitable for routine analytical applications.