Oral Bioavailability and Pharmacodynamic Activity of Hesperetin Nanocrystals Generated Using a Novel Bottom-up Technology

In the present study, nanocrystalline solid dispersion (NSD) was developed to enhance the release rate and oral bioavailability of hesperetin (HRN). NSD of HRN was prepared using a novel bottom-up technology platform. It is a spray drying based technology to generate solid particles, containing drug nanocrystals dispersed in small molecule excipients. HRN and mannitol were used in a 5:5 ratio, and an average crystallite size of HRN in NSD with mannitol was found to be 137.3 ± 90.0 nm. An in vitro release study revealed a statistically significant release rate enhancement for HRN nanocrystals (46.3 μg/mL/min) as compared to that of the control (29.5 μg/mL/min). Further, a comparative oral bioavailability study of NSD and control in Sprague–Dawley rats established significant improvement in C_max and oral bioavailability (AUC_0–∞) by 1.79- and 2.25-fold, respectively, for HRN nanocrystals. The findings of oral bioavailability were corroborated by intestinal uptake and Caco-2 cell uptake studies, wherein HRN, when administered in nanocrystalline form, showed higher penetration in intestinal mucosa and higher uptake in Caco-2 cells. Finally, the therapeutic efficacy of HRN nanocrystals was tested by a reactive oxygen species (ROS) generation assay and carrageenan induced anti-inflammatory model. HRN nanocrystals markedly inhibited ROS generation in MCF-7 cells, and carrageenan induced inflammation in rats. The process of NSD formation was found to be based on classical nucleation theory wherein mannitol contributed to NSD formation by acting as a plasticizer and crystallization inducer, and by providing sites for heterogeneous nucleation/crystallization.