OBJECTIVE To develop a spray film former containing salidroside for the treatment of stress fracture.

METHODS Using salidroside as the model drug, the formulation was optimised through single-factor experiments combined with a central composite design-response surface methodology(CCD-RSM). The prepared salidroside spray film former underwent quality evaluation, formulation characterisation, and in vitro release studies. A physical skin model was constructed, and the in vitro diffusion process of the drug was simulated using finite element analysis.

RESULTS The optimal formulation for the prepared salidroside spray film former comprised: ‌Each 100 mL of salidroside spray film former contained polyvinyl alcohol(PVA)1.42 g, polyvinylpyrrolidone(PVP-K30)0.47 g, hydroxypropyl methylcellulose(HPMC) 0.1 g, glycerol 4 mL, anhydrous ethanol 24.2 mL, with the final volume adjusted to 100 mL with purified water. The resulting formulation appeared transparent and clear, with a pH of 5.12, approximating the average pH of human skin. Microscopic examination revealed a film devoid of bubbles or particles, exhibiting excellent uniformity. Scanning of absorbance and transmittance under ultraviolet and infrared spectroscopy showed the drug-containing formulation to be essentially identical to the blank formulation, indicating good compatibility and uniform drug dispersion. In vitro transdermal permeation studies demonstrated the formulation possessed favourable sustained-release properties. Further skin diffusion simulation results indicated the drug gradually permeated from the stratum corneum into the epidermis over time, ultimately diffusing into the dermis.

CONCLUSION The preparation process of salidroside spray film former is simple and feasible, with good drug-formulation compatibility and adaptability to human skin pH.