SOLUBILITY ENHANCEMENT AND FTIR COMPATIBILITY CHARACTERIZATION OF A SOLUPLUS-BASED SOLID DISPERSION OF DEXLANSOPRAZOLE

Abstract

Objective: To prepare dexlansoprazole–Soluplus® solid dispersions by solvent evaporation, compare their saturation solubility at pH 1.2 and pH 6.8 and evaluate drug–polymer compatibility using Fourier-transform infrared (FTIR) spectroscopy. Methods: Dexlansoprazole–Soluplus® dispersions were prepared at drug-to-polymer ratios of 1:1,1:2 and 1:3 using 95% ethanol. The solvent was removed by rotary evaporation, followed by vacuum drying, pulverization and sieving. Physical appearance, practical yield and drug content were evaluated. Saturation solubility was determined by the shake-flask method at pH 1.2 and pH 6.8 at 37 ± 0.5°C for 48 hours, with spectrophotometric quantification at 285 nm. FTIR spectra of dexlansoprazole, Soluplus®, the physical mixture and the selected dispersion were recorded from 4000–400 cm⁻¹. Results: All dispersions were homogeneous. Practical yield increased from 94.2 ± 0.8% for ASD-1 to 97.8 ± 0.4% for ASD-3, while drug content ranged from 98.4 ± 0.6% to 100.9 ± 0.5%. At pH 6.8, saturation solubility increased from 82.4 ± 2.1 µg/mL for pure dexlansoprazole to 215.7 ± 4.8, 328.5 ± 5.3, and 465.2 ± 6.8 µg/mL for ASD-1, ASD-2, and ASD-3 respectively. ASD-3 therefore produced a 5.65-fold increase over the pure drug. At pH 1.2, ASD-3 reached 12.7 ± 0.7 µg/mL versus 1.5 ± 0.2 µg/mL for pure drug. FTIR retained the principal characteristic bands without a new major absorption band. Conclusion: Soluplus® progressively enhanced dexlansoprazole saturation solubility with the 1:3 formulation showing the greatest improvement under the tested conditions. FTIR findings supported drug–polymer compatibility. These findings justify further development of the optimized dispersion using complementary solid-state characterization and stability studies.