In vivo evaluation of physiological efficacy of insulin-loaded nanoliposomes prepared for oral delivery

Oral delivery is the most favorable route for insulin administration. The aim of this study was to generate new chitosan coated insulin nanoliposomes and then to assess the physiological efficacy of these nanoliposomes after oral administration in diabetic rabbits. Nanoliposomes with negative surface charge encapsulating insulin were prepared by reverse phase evaporation method. To prepare nanoliposomes, lecithin, cholesterol, acetyl-diphosphate and β-cyclodexterin were used. Then, nanoliposomes were coated by means of incubation with the chitosan solution. The encapsulation efficiency of prepared nanoliposomes was measured by spectrophotometry technique after dissolution of the nanoparticles. The hypoglycemic efficacy of chitosan-coated insulin nanoliposomes were investigated by monitoring the blood glucose level after oral administration to diabetic rabbits. Insulin entrapment efficacy for preparation of new formulated nanoliposomes 79±0.16 were significantly higher than other formulations (p<0.05). The in vivo results clearly indicated that the insulin-loaded nanoliposomes could effectively reduce the blood glucose level in diabetic rabbits from 250±0.75 mg/dl to 125±0.98 mg/dl after 4 hours. The results clearly suggest that nanoliposomes may be considered as a good tool for oral insulin delivery.