Otimização do processo de produção piloto e desenvolvimento de um programa de liofilização de lipossomas pH-sensíveis de circulação prolongada contendo cisplatina

Abstract

The CDDP entrapment into liposomes is an alternative to circumvent severe side effects and increase antitumor drug bioavailability in the tumor. For pre-clinical and clinical studies, the large scale production of liposomes with high encapsulation efficiency, homogeneous size distribution and a good storage stability is required. Since aqueous liposome dispersions are unstable, freeze-drying in the presence of cryoprotectants is widely used to obtain a commercial product. In order to design an optimum freeze-drying process, it must be developed at a rational manner. The critical temperatures of the formulation, the stability of the drug and the properties of the excipients must be investigated so that there is reproducibility between lots in large-scale production of liposomes. The aim of this work was to evaluate the process parameters for the optimization of pilot production and to develop a freeze-drying process of long-circulating and pH-sensitive liposomes containing cisplatin (SpHL-CDDP). The REV method, using ethyl ether as organic solvent, followed by homogenization at 500 bar for 6 cycles and ultrafiltration as purification method, and the CDDP initial concentration of 0.5 mg/mL were the parameters chosen for the production of SpHL-CDDP in pilot scale. SpHL-CDDP presented a mean diameter of 94.6 nm, monodisperse size distribution, zeta potential of 3.1 mV and an encapsulation percentage of 30.2 %. The lyophilization of SpHL-CDDP, containing trehalose at the sugar:phospholipid (w/w) ratio of 2:1, was performed by slow freezing, primary drying at -35ºC and 100 mTorr, secondary drying at 25ºC and 100 mTorr. It lasted approximately 27 hours and produced a white and elegant cake which showed a residual moisture of 2.81 %. After reconstitution of freeze-dried SpHL-CDDP, the liposomes were able to retain 87.5 % of CDDP and resulted in vesicles of mean diameter of 302.2 nm, zeta potential of 4.4 mV and heterodisperse size distribution.