HYPOGLYCEMIA AFTER LIPOSOMIZED INSULIN IN THE RAT: 55

Abstract

The use of liposomes as carriers or vehicules for drugs has been investigated. An interesting feature is the capability, the liposomes have for protecting molecules, for instance their capacity for preventing contact and interaction of labile substances with the gastro-intestinal fluids.The efforts in these laboratories have centered on insulin as the active ingredient. The liposomes are prepared using a 7 : 2 mixture of dipalmitoylphosphatidylcholine (DPPC) and cholesterol, sonicated for 2 minutes. The non-liposomized insulin is separated out by ultracentrifugation and the liposome fraction then suspended in a pH 7.2 phosphate buffer.The in vivo effects have been established by intraperitoneal injection into normal male wistar rats. An intraperitonealy administered dose of 0.5 ml of insulin/liposome causes hypoglycemia (54 % of initial blood glucose value) in 9 out of 10 rats in one hour and causes death in 9 out of 10 rats in two hours. When given orally the resulting hypoglycemia is 31 % of the initial value one hour after administration and 50 % after 2.5 hours in 8 out of 10 rats.The initial results are encouraging and demonstrate the protecting action of the liposomes although there are still problems to be solved.