Mechanisms of action of transportation of liposomes and chitosan-coated liposomes containing leuprolide across intestine and Caco-2 cell

AimTo investigate the mechanisms of action of transportation of liposomes and chitosan-coated liposomes containing leuprolide across rat intestine and Caco-2 cell. MethodsEverted-gut technique and Caco-2 cell were used to study the transport properties of free leuprolide, liposomes and chitosan-coated liposomes containing leuprolide. Caco-2 cell was used to study the effect of chitosan concentration and the order of addition on the permeation of liposomes. ResultsThe transport of leuprolide was passive diffusion. Probably because the entrapment by liposomes prevents the transport of leuprolide across the rat intestine and Caco-2 cell, the permeation amount of leuprolide from liposomes was lower than that of the free drug. However, liposomes protected the leuprolide from degradation. Chitosan promoted the transport of leuprolide from liposomes and there was no obvious difference in enhancement effect from the concentration of 0.1% to 0.5%. On the other hand, the incubation of chitosan with liposomes may weak the enhancement effect of chitosan. ConclusionChitosan-coated liposomes showed both protection and enhancement effect, therefore, they may promote the oral absorption of leuprolide.