Effects of oral administration of positively charged insulin liposomes on alloxan diabetic rats: Preliminary study.

Abstract

Insulin encapsulated in liposomes of various lipid compositions were prepared. The amount of insulin trapped in these liposomes increased in the order, negatively charged liposomes less than neutral liposomes less than positively charged liposomes. In positively charged liposomes, the amount of insulin trapped increased with increase in the amount of amphiphile stearylamine. Under the conditions tested, the highest insulin content (about 50%) was obtained with liposomes composed of phosphatidyl choline/cholesterol/stearylamine in a molar ratio of 7/2/2.25. These liposomes were stable on incubation for 3 hr at 37 degrees C in solutions of pepsin, trypsin, and pancreatin, and after these incubations, a considerable amount of insulin was still associated with the liposomes. However, the liposomes released almost all the insulin into the medium on treatment with bile. When the liposomes were administered orally to rats in the 3rd phase of acute alloxan diabetes, reduction of the blood glucose level was observed in 7 of 11 animals, the reduction persisted for several hours and was ranging from 30 to 75%. In alloxan diabetic rats showing hyperglycemia for 3 to 6 months, the liposomes also increased the glucose tolerance in half the animals tested.

In vivo efficacy of a novel double liposome as an oral dosage form of salmon calcitonin

“…smaller than 300 nm passed through Peyer's patches and entered the systemic circulation [Jani et al, 1990]. Hashimoto and Kawada reported that use of cationic liposomes improved the intestinal absorption of insulin [Hashimoto and Kawada, 1979]. Similarly, the findings of the present study also verified that not only the particle size but also the electrical charge of the inner liposomes in DL affects intestinal absorption.…”

Oral Administration of Recombinant Human Erythropoietin in Liposomes in Rats: Influence of Lipid Composition and Size of Liposomes on Bioavailability

“…Regarding liposome size, Aramaki et al reported that multilamellar liposomes (MLV) larger than 374 nm in size were taken up through rat Peyer's patches after oral administration using isolated tissues. 28 The MLV liposomes have been used in many cases for oral administration, [11][12][13][14][15] while REV liposomes have not.…”

“…[11][12][13][14][15] The use of liposomes as carriers of cytokines, 16 interleukin-2, 17 interleukin-7, 18 and interferon 19 has been reported, but that of Epo has not been studied in the past.…”

Effects of Gastrointestinal Administration of Human Insulin and a Human Insulin-Deae-Dextran Complex Entrapped in Different Compound Liposomes on Blood Glucose in Rats

“…The infusion systems for insulin have also been developed (2 These include the finding of new insulin derivatives (4-61, a suitable dosage form (7,8) and a proper drug carrier which 1s stable in the gastrointestinal fluids such as the entrapment of the hormone in liposomes (9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19). Insulin together with soybean trypsin inhibitor has been directly injected to rat ileum resulting in a significant drop in blood glucose (7).…”

“…Varying of these physical properties can also affect the location and the rate of metabolism of the liposomes as well a s the drugs being entrapped. Recently, an extensive investigation on t h e use of liposomes as carriers for the introduction of insulin via the oral route has been focussed (9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19).…”