Computational and experimental approaches for HPMCAS-based solid dispersions of abiraterone acetate: formulation,...

To enhance the solubility and dissolution rate of poorly watersoluble drug Abiraterone Acetate (ABA) by developing solid dispersions using hydroxypropyl methylcellulose acetate succinate (HPMCAS-LF).

Enhancing the biopharmaceutical performance of ABA is crucial due to its extremely poor solubility and dissolution characteristics. The present study demonstrates that HPMCAS-LF-based solid dispersion effectively improves the physicochemical performance of ABA through enhanced solubility, dissolution, and in vitro drug diffusion.

Molecular dynamics (MD) simulations were conducted over 100 ns to evaluate the stability and structural behavior of the ABA-HPMCAS-LF complex, with analyses including root mean square deviation (RMSD), radius of gyration and solvent-accessible surface area. Binding free energy was measured using MM-GBSA calculations. Solid dispersions were prepared using cogrinding and solvent assisted cogrinding techniques and characterized by FTIR, PXRD, thermal analysis (TGA/DTG-DTA), SEM, and solid-state¹³C NMR. Solubility, in vitro dissolution, in vitro drug diffusion, hygroscopicity, and anticancer activity were assessed.

The ABA-HPMCAS-LF complex exhibited dynamic stability, with RMSD stabilization at 6-7 Å and a binding free energy of -33.45 kcal/mol, indicating strong van der Waals, lipophilic, and Coulombic interactions. Solid dispersions demonstrated a 1.07 to 16.72-fold increase in solubility compared to pure ABA, and in vitro release enhanced drug dissolution across different media. Diffusion increased by 6.36-fold in simulated gastric fluid (SGF 1.2) and 2.55-fold in phosphate buffer (pH 6.8) relative to pure ABA.

The solid dispersion of ABA with HPMCAS-LF significantly improved solubility, dissolution, and diffusion, highlighting its potential for enhanced oral bioavailability and improved therapeutic outcomes.