Helena Ferreira, Artur Ribeiro, Raquel Silva and Artur Cavaco-Paulo
Deformable Liposomes for the Transdermal Delivery of Piroxicam
Abstract
Objective: Deformable liposomes have been used to improve drugs transdermal delivery. These vesicular systems were employed to deliver piroxicam through the skin as a mean to treat inflammatory diseases and avoid undesired side-effects.
Methods: Deformable liposomes, composed by egg-yolk phosphatidylcholine, sodium cholate and α-tocopherol, were prepared by the thin film hydration method followed by extrusion. Piroxicam was included into the lipid bilayer or in the aqueous phase using inclusion complexes of piroxicam with β-cyclodextrin. After characterization, it was evaluated their in vitro permeation using Franz diffusion cells with polysulfone membranes or pig skin.
Results: The entrapment of piroxicam in the aqueous compartment, through the use of β-cyclodextrin inclusion complexes, enabled higher entrapment efficiency (63.27% more than when entrapped in the lipid bilayer). The optimized deformable liposomes population were homogeneous (PDI < 0.1) in terms of size (108.93 ± 3.74 nm) and presented a spherical shape. Size stability studies demonstrated that the vesicles were stable along two months of storage. In vitro permeation studies using Franz diffusion cells and polysulfone membranes showed that the vesicles own enough deformability to pass through pores smaller than their own size in a percentage ≈ 45%. Furthermore, a constancy of their diameter and morphology was verified after pores passage. In the experiments performed with pig skin, the permeation of the deformable liposomes incorporating piroxicam β-cyclodextrin complexes decrease considerably. After 24 h of diffusion, only 1.1-3.2 % of the initial population reached the liquid receptor as result of the presence of the stratum corneum which is the main barrier of the skin. Nevertheless, the histological studies demonstrated that deformable liposomes were uniformly distributed on the skin structure and thus were able to achieve a percutaneous permeation of their content.
Conclusion: The results support the possibility to use this formulation on the topical treatment of inflammatory conditions.
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