engleski

Compaction of pre-liposomal tablets governing in situ formation of liposomes

Purpose. The aim of the current study was to investigate the concept of tableting spray-dried pre-liposomes. To distinguish these types of systems from proliposomes prepared by other methods, we named the systems pre-liposomes (PreLipo) [1]. Methods. PreLipo powders, drug loaded and empty, were prepared by direct spray-drying of a mixture of lipid (lecithin), metronidazole and mannitol [1], and characterized with respect to morphology, particle size and powder flowability. PreLipo powder was mixed (15:85 w/w) with tableting excipients (microcrystalline cellulose, mannitol, lactose monohydrate, pregelatinized starch, dibasic calcium phosphate, pectin or chitosan), and compressed into tablets (6 mm, 75 mg, 100 MPa). The tablets were characterized with respect to mechanical and drug release properties. The Pre-Lipo tablets were disintegrated and the in situ formed liposomes characterized with respect to vesicle size and zeta potential, and compared to liposomes formed by direct hydration (without compaction) of the PreLipo powder. Results. The Pre-Lipo powder was free-flowing, and tablets of similarly high qualities as tablets made of physical mixtures were prepared with all tableting excipients. Liposomes were formed in situ upon tablet disintegration, dissolution or erosion depending on the type of tableting excipient used. The liposomal characteristics and drug release were found to depend on the tablet excipient. Conclusions. PreLipo tablets offer a unique synergy between the ability of liposomes to encapsulate and protect drugs, and increased stability provided by solid formulations. They can be adjusted for drug administration via various routes, e.g. oral, buccal and vaginal.

pre-liposomes; spray drying; tablet

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