Elastic liposome-based gel for topical delivery of 5-fluorouracil: in vitro and in vivo investigation

Objective: This investigation has focused to characterize the elastic liposome containing 5-fluorouracil (5-FU) and to enhance drug permeation across stratum corneum (SC) of the skin (rat) using various surfactants and in vivo dermal toxicity evaluation. Methodology: 5-FU-loaded elastic liposomes were developed, prepared and characterized for their entrapment efficiency, vesicle size, number of vesicles, morphological characteristics, surface charge and turbidity. In vitro drug release profile, in vitro skin permeation potential and in vitro hemolytic ability of the formulation have been evaluated to compare with drug solution for 24 h. In vitro skin permeation potential was also compared with marketed cream. Furthermore, in vivo skin irritation potential, drug penetration into the skin using confocal laser scanning microscopy (CLSM) and in vivo toxicity studies were performed. Results and conclusions: The optimized elastic liposomes demonstrated maximum drug entrapment efficiency, optimum vesicular size and considerable elasticity. In vitro skin permeation studies showed the highest drug permeation flux like 77.07 +/- 6.34, 89.74 +/- 8.5 and 70.90 +/- 9.6 mu g/cm(2)/h for EL3-S60, EL3-S80 and EL3-T80, respectively, as compared to drug solution (8.958 +/- 6.9 mg/cm(2)/h) and liposome (36.80 +/- 6.4 mg/cm(2)/h). Drug deposition of optimized elastic liposome EL3-S80 was about three fold higher than drug solution. Skin irritation and CLSM studies suggested that optimized gel was free from skin irritation and capable to deliver 5-FU into the epidermal area for enhanced topical delivery than drug solution. The in vitro study showed minimum hemolysis in the optimized formulation. Finally, in vivo toxicity studies followed with hisptopathological assessment showed that elastic liposome was able to extract SC to improve drug permeation without changing general anatomy of the skin.