Development and Optimization of a Feronia elephantum Leaf Extract Ointment: A QbD-Based Approach for Enhanced Anti-Inflammatory Activity

Feronia elephantum possesses significant therapeutic potential owing to its rich phytochemical composition and traditional use in inflammatory disorders. The present study aimed to develop, optimize, and evaluate a topical herbal ointment containing Feronia elephantum leaf extract using a Quality by Design (QbD) approach. The hydroalcoholic extract was prepared by maceration and characterized using FTIR, DSC, and UV spectroscopy. FTIR analysis confirmed the presence of phenolic and flavonoid constituents, while DSC revealed a characteristic endothermic peak at 123.92°C. UV analysis showed a maximum absorption wavelength (λmax) at 275 nm. Extract–excipient compatibility studies demonstrated the absence of significant interactions between the extract and selected excipients. A 2³ full factorial design was employed using cetostearyl alcohol, lanolin, and liquid paraffin as critical material attributes, while viscosity and percentage drug release were selected as critical quality attributes. Eight formulations were prepared and evaluated for physicochemical properties, drug content, spreadability, extrudability, homogeneity, in vitro drug release, and anti-inflammatory activity. The formulations exhibited viscosities ranging from 1450 to 2520 cP and cumulative drug release between 75.2% and 91.8%. Statistical analysis showed that cetostearyl alcohol and lanolin significantly influenced both viscosity and drug release (p < 0.0001). The optimized formulation (F4) demonstrated a viscosity of 2105 cP and drug release of 82.4%. In vitro anti-inflammatory evaluation using the HRBC membrane stabilization method showed that the ointment formulation produced 29.0 ± 1.0% and 46.0 ± 1.0% membrane protection at 200 and 400 mg/mL, respectively, compared with 25.0 ± 1.0% and 41.0 ± 1.0% for the crude extract. Accelerated stability studies indicated minimal changes in pH (6.45–6.61), viscosity (2105–2102 cP), and drug content (95.86–95.30%) over three months. In conclusion, the QbD-optimized Feronia elephantum ointment exhibited satisfactory physicochemical characteristics, controlled drug release, enhanced anti-inflammatory activity, and good stability, indicating its potential as an effective topical herbal formulation for inflammatory conditions.