Orthogonal experimental preparation of Sanguis Draconis- Polyvinylpyrrolidone microfibers by electrospinning.

How to improve the bioavailability of the Sanguis Draconis (SD) is an important problem in the potential clinical applications. The aim of this study was to develop a drug delivery system to achieve high bioavailability of SD, a drug with poor water solubility. It will promote the research about new formulations of the SD and the other insoluble drugs. In this study, a highly biocompatible hydrophilic polymer, polyvinylpyrrolidone (PVP), was selected as a carrier, mixed with different proportions of SD to produce SD-PVP microfibers by solution electrospinning. By orthogonal experiments, the optimal spinning conditions of the preparation of SD-PVP fibers were investigated. The morphology of different proportions of SD-PVP microfibers was observed by scanning electron microscopy, and the phase characteristics were characterized by Fourier transform infrared spectrometry, X-ray diffraction, and differential scanning calorimetry. The hydrophilic properties of SD-PVP fiber membranes with different SD content were analyzed by the water contact angle assay. In vitro dissolution experiments were carried out to observe the dissolution of drugs in SD-PVP fiber membranes. The results showed that the diameter of SD-PVP fibers increased with the enlargement of SD content. A eutectic mixture was formed after blending PVP and SD, and the hydrogen bonds were formed between the SD and PVP with no chemical reaction occurred. The dispersion of SD in the fiber decreased with the increase of SD content. The higher the content of SD in the fiber, the more hydrophobic the fiber membrane. In vitro dissolution studies revealed that the dissolution content of SD from SD-PVP microfibers was significantly higher than that of the pure or original drug SD. However, as the SD content increased from 15% to 30%, the dissolution of the drug in the SD-PVP fibers decreased. The SD-PVP fiber prepared in this study showed much higher solubility than the original drug in vitro, which has great significance for the development of new dosage forms for the clinical application of SD, and it has a useful reference for the study of similar bioavailability of poorly soluble drugs.