Nanoliposomes in polymeric granules: Novel process strategy to produce stable and versatile delivery systems

Liposomes, due to their mimetic cellular composition, are gaining great attention as release systems for lipophilic and hydrophilic molecules. However, liposomes can present a high tendency to degrade and aggregate into biological fluids and under storage conditions. To overcome these limitations, in this work, a stabilizing strategy consisting in liposomes incorporation into polymeric granules was studied. Wet granulation was adopted to produce granules of hydroxypropyl methylcellulose (HPMC) and liposomal suspensions were used as the binder phase. In particular, in this study, three different percentages of liposome load in HPMC granules were investigated (1%, 5% and 10% w/w) focusing the attention on several relevant technological characteristics of the achieved solid particulates: size, flow index, mechanical strength (granules without liposomal inclusions were used as a control). Morphological observations (by TEM) confirmed the presence of intact liposomes in dry HPMC granules; moreover, it was found that the binder phase with the lower liposome concentrations (1%, 5%) did not significantly affect size, flowability and hardness of the lipid-polymer granules. Instead, the granules containing the highest percentage of liposomes (10% w/w) have larger dimensions, harder structure and reduced flowability. Therefore, the followed process strategy, under liposomal concentration restrictions, allowed to obtain both the liposomes stabilization, a not trivial technological issue, and the production of particulates with good solid state properties, useful as a versatile dosage form (lipid carriers in polymer carriers).