Development and characterization of nanocrystals for solubility enhancement of poorly soluble drug azelnidipine

Background: Azelnidipine is a BCS Class II drug characterized by low solubility and high permeability, resulting in approximately 50% bioavailability. The limited bioavailability of this compound is primarily attributed to its poor aqueous solubility. Therefore, enhancing the solubility and dissolution rate of Azelnidipine is essential to improve its bioavailability. This study aimed to develop and characterize Azelnidipine Nanocrystals to enhance the solubility and dissolution rate of Azelnidipine, which is currently in micronized form. Methodology: Azelnidipine nanocrystals were prepared via antisolvent precipitation. Azelnidipine nanocrystals were synthesized using PVP and SLS as stabilizers via a precipitation process. Saturation solubility was tested in 5 mL of 0.1 N HCl and in phosphate buffers at pH 6.8 and 7.4. The physicochemical properties of the nanocrystals, including physical appearance, FTIR, DSC, SEM, XRD, solubility, particle size distribution, zeta potential, and in vitro drug release, were evaluated. Results and Discussion: FTIR spectroscopy confirmed drug compatibility and ruled out potential interactions with the polymers. Nine nanocrystal formulations (F1 to F9) containing pure Azelnidipine in micronized form with varying percentages of PVP and SLS stabilizers were tested. In batches F1 to F3, the drug-to-polymer PVPK30 ratio was 1:1, and the SLS concentration was increased by 0.05, 0.10, and 0.150, yielding the highest drug release in batch F3 (97.68%). The study found that as SLS concentration increased, solubility increased; similarly, as particle size decreased, solubility increased. Conclusion: Conversion of the micronized form of Azelnidipine to the nanocrystal form increases its solubility.