Novel microstructured sildenafil dosage forms as wound healing promoters

Purpose: Study the possible benefit of combining biodegradable polymers with sildenafil citrate (SC) in wound healing. Method: Biodegradable micronized powdered formulations of SC were prepared by spray drying using chitosan (P-1) or chitosan/gum Arabic (P-2). Powders were characterized by differential scanning calorimetry, Scanning electron microscope, particle size analysis, flow and swelling behavior. The powders were also incorporated into microstructured gels and in vitro SC release from powders and gels was tested. In vivo wound healing acceleration was tested by measuring area contraction of excision wounds and histologically. Post-healing tensile strength (TS) for incision wounds in rats receiving powder formulations was tested. Results: The powders were in the micron-size range showing no SC-polymers interaction. Powders had poor flow with angle of repose (theta) of 41 - 48 degrees, and high moisture uptake reaching 107% for placebo powder P-o1. Good excision wound healing was seen with P-1 and G(1) formulations showing 98.4 and 98.5% reduction in wound area, respectively, compared with 83% for the control. Incision wounds were improved with P-1 showing TS value of 6.9 compared with 3.7 kg/cm(2) for control. Histological examinations supported. Conclusion: Spray-dried chitosan/SC powder (P-1) and its gel form (G(1)) could be promising wound healing promoters as supported by the histological examinations.