Background: Insulin has been included in a variety of dosage forms; nevertheless, liposomes
have shown protection to degradation and better absorption. The addition of surfactant to liposomes
could give the ability to deform and pass through intact membranes, and could increase the
stability and the release of the drug.
Introduction: Due to the limitations of the current treatment of insulin in diabetic patients, investigation
in alternatives routes has increased. The oral route is the most convenient because of the
similarity with the natural secretion of this hormone. The aim was to evaluate the in-vivo effect of
fourteen formulations of Insulin-loaded flexible liposomes with different surfactants by oral and
Methods: Fourteen formulations of insulin were obtained with the addition of different surfactants.
Size distribution, polydispersion index and Z potential were obtained for all formulations. In-vivo
tests were performed in rats induced with experimental diabetes with streptozotocin, and glucose
curves were obtained during 480 minutes.
Results: All formulations by the subcutaneous route caused an optimal reduction in glucose levels.
However, the addition of Brij L23 produced a better reduction, lasting for 420 minutes. By the oral
route, the reduction of glucose did not reach the normal levels, but the addition of Poloxamer 407
and Brij S10 showed the best reduction in the glucose levels by this route.
Conclusion: The addition of surfactants to the lipid structure can modify the release of the insulin
by different routes of administration, but this behavior depends on the characteristics of the surfactant,
such as the melting phase transition temperature of the lipid bilayer.