Preparation and Evaluation of Tetrandrine Nanocrystals to Improve Bioavailability.

Background: Tetrandrine (TET) has multiple pharmacological activities, but its water solubility is poor, which is the main reason for its low bioavailability.

Objectives: The purpose of this study was to prepare TET nanocrystals (TET-NCs) using a grinding method to enhance the dissolution rate and ultimately improve the bioavailability of TET.

Methods: TET-NCs were synthesized via media milling, employing Poloxam 407 (P407) as surface stabilizer and mannitol as a cryoprotectant during freeze-drying. The crystal structure, particle diameter, and zeta potential were characterized using differential scanning calorimetry (DSC), Fouriertransform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The in vitro release behavior and pharmacokinetics of TET-NCs were assessed. The cytotoxicity of TET and TET-NCS on RAW264.7 cells was determined by the CCK-8 method.

Results: The particle size of TET-NCs was 360.0±7.03 nm, PDI was 0.26±0.03, and zeta potential was 6.64±0.22 mV. The cumulative dissolution within 60 minutes was 96.40±2.31%. The pharmacokinetic study showed that AUC0-72 h and Cmax of TET-NCs were significantly enhanced by 3.07 and 2.57 times, respectively, compared with TET (p<0.01). TET-NCs significantly increased the cell inhibition on RAW264.7 cells compared to the TET (P<0.01).

Conclusion: The preparation of TET-NCs enhanced dissolution rate and bioavailability significantly, and it also improved the inhibition effect of RAW264.7 cells.