In vitro evaluation and in situ intestinal absorption characterisation of paeoniflorin nanoparticles in a rat model

Purpose: the aim of this study was to improve the stability and bioavailability of paeoniflorin (PF) by using nanoparticle encapsulation technology. Methods: paeoniflorin nanoparticles (PF NPs) were prepared with PLGA as the carrier using the compound emulsion method. The nanoparticles were characterised by using a Malvern laser particle sizer, transmission electron microscope (TEM), X-ray diffraction (XRD) analyser, and Fourier-transform infrared (FT-IR) spectrometry. The PF NPs were subjected to a series of stability investigations (such as for 4 °C storage stability, pH stability, and thermal stability), lyophilisation protection technology investigations, and in vitro release studies. Finally, the intestinal absorption properties of PF and PF NPs were studied by the in situ single-pass intestinal perfusion (SPIP) rat model, using the effective permeability coefficient (P _eff) and the absorption rate constant (K _a) as relevant indexes. Results: the prepared nanoparticles had a particle size of 105.0 nm with blue opalescent, rounded morphology, uniform size, good stability and slow release. We found that 4% alginate was the best lyoprotectant for the PF NPs. In the intestinal absorption experiments, P _eff was higher for the PF NPs group compared with the original PF material drug group in all intestinal segments (P < 0.05), and the absorption rate constant K _a increased with the increase in the drug concentration. Conclusion: the nanoparticles produced by this method have good stability and a slow-release effect; they can thus improve the absorption of PF in rat intestines, helping improve the stability and bioavailability of PF and enhancing its pharmacological effects.