Lipid-based microtubes as pro-pharmacosomes for amphotericin B

SALERNO C; SCIOSCIA S; CUESTAS ML; CHIAPPETTA DA; BREGNI C; LUCANGIOLI S

Congreso; RICiFa, 4ta Reunión Internacional de Ciencias Farmacéuticas; 2016

Self- assembled nanocarriers are of much interest since they can be produced by simple low cost, solvent-free procedures. Lipid-based microtubes (MTs) are supramolecular structures usually self-assembled from amphiphiles (1-3). We have reported the incorporation of amphotericin B (AmB) into 12-hydroxystearic acid MTs (4). Herein we report the ability of AmB-MTs to self-assemble into vesicles upon dilution leading to smaller structures which could be promising for AmB delivery by inhaled administration. In vitro antifungal susceptibility testing against Aspergillus fumigatus was also assayed. AmB-MTs with different drug concentrations (1,3,5 mg/ml) were prepared as previously reported (4). Size determination was carried out for different dilutions (1/5, 1/10 and 1/100) at 25 ºC (NanoZetasizer-ZS; Malvern Instrument, UK); the reported values are the average of at least 3 measurements. Transmission electron microscopy was performed using a Zeiss 10C by placing a drop of dispersions on a copper grid with a Formvar membrane and covering the grid with 2% uranyl acetate solution. In vitro activity against A. fumigatus was assessed by the microdilution method in a 96-well plate; the final concentrations of the formulation, after the addition of conidia inocula of A. fumigatus ATCC 15560 ranged from 1 to 0.03 µg/ml in RPMI 1640 medium with MOPS and 2%DMSO. Incubation was at 37ºC; readings were made at 24 and 48 h. AmB raw material and AmB deoxycholate were used as control and reference respectively; blank MTs were used as negative control, media sterility and media growth control were also performed. Results showed that AmB-MTs close upon dilution to form vesicles; size range depending on AmB concentration and dilution from 200 nm to 1µm. The formulation showed proper inhibition of A. fumigatus growth; the activity was not affected by the lyophilization process (MIC: 0.0625 and 0.125 µg/ml for dispersion and reconstituted lyophilized, respectively). MTs are promising as pro-pharmacosomes for AmB.