Enhancing the Solubility and Dissolution of Apigenin: Solid Dispersions Approach

Apigenin (APG), a bioactive flavonoid with promising therapeutic potential, suffers from poor water solubility, which limits its bioavailability. To address this, solid dispersions of APG were prepared using ball milling with sodium alginate (SA), Pluronic^® F-68 (PLU68), Pluronic^® F-127 (PLU127), PVP K30, and PVP VA64 as polymeric excipients. These dispersions were screened for apparent solubility in water and buffers with pH 1.2, 5.5, and 6.8. Based on improved solubility after 60 min, APG-PLU68 and APG-PLU127 dispersions were selected for further study. DSC and FT-IR analysis confirmed molecular interactions between APG and the polymer matrices, contributing to enhanced solubility and dissolution rates. Dissolution rate studies showed that APG-PLU127 achieved 100% solubility at pH 6.8, suggesting its potential use in environments such as the small intestine. Additionally, APG-PLU127 exhibited 84.3% solubility at pH 1.2, indicating potential for solid oral dosage forms, where APG could be absorbed in the acidic conditions of the stomach. The stability study confirmed that storage for one year under ambient conditions does not cause chemical degradation but affects the physical state and solubility of the dispersion. Antioxidant activity was assessed using the ABTS assay. Freshly obtained APG-PLU127 showed 68.1% ± 1.94% activity, whereas APG-PLU127 stored for one year under ambient conditions exhibited 66.2% ± 1.62% (significant difference, p < 0.05). The difference was related to a slight decrease in the solubility of APG in the solid dispersion (T0 = 252 ± 1 μg∙mL^-1, T1 = 246 ± 1 μg∙mL^-1). The findings demonstrate the superior performance of PLU127 as a carrier for enhancing the solubility, release, and antioxidant activity of APG.