AIM To evaluate influence of pyrrolidone having different molecular weights on the
hypoglycemic effect of insulin liposomes
after oral administration in mice. METHODS Insulin- liposomes were prepared by reversed-phase evaporation. The particle size and morphology of insulin-liposomes were determined using laser light scattering instrument and transmission electron microscopy (TEM)
respectively. The entrapment efficiency was analyzed by HPLC and ultracentrifuge. The protection of insulin from peptic and tryptic digestion was studied with HPLC. The hypoglycemic effects of insulin liposomes were investigated using the glucose oxidase method after oral administration in mice. RESULTS The particle size of the insulin liposomes containing PVP-K17, PVP-K30 and PVP-K90 was 180±36.7 nm, 172.7±38.0 nm and 159.2±34.2 nm respectively. The shape of insulin-liposomes showed the shape of sphere or ellipsoid. The entrapment efficiencies were 64. 4% , 62. 8% and 57. 5% respectively. The protection of insulin from peptic digestion dependent on molecular weight of PVP, and enhanced with increasing the molecular weight of PVP. But no protection of insulin from tryptic digestion was occurred. The
hypoglycemic effect of insulin-liposomes containing PVP-Kso was superior to that of insulin-liposomes containing PVP-K17 and PVP-K90. CONCLUSION PVP-K30 is superior to the hypoglycemic effect of insulin-liposomes after oral administration in mice.