Preparation And Mechanism Study On A Novel Pirarubicin Liposome Powder

Pirarubicin (THP), a commonly used anthracycline, has gained widespread applications against acute leukemia, malignant lymphoma, breast cancer, gastrointestinal cancer, liver cancer, lung cancer and some solid tumors. However, there are several adverse effects in the clinics:1, bone marrow suppression and severe gastrointestinal reactions; 2, cumulative cardiotoxicity:THP has a progressive dose-dependent cardiotoxicity that irreversible evolves toward congestive heart failure. Liposome drug delivery system, which can alter the in vivo behavior of the encapsulated drug, was expoited to provide a strategy for limiting or preventing the cardiotoxicity of THP.Interaction between pirarubicin and distearylphosphatidylcholine (DSPC) or distearylphophatidylglycerol (DSPG) was investigated by means of differential scanning calorimetry (DSC), fourier transform infrared (FTIR) spectroscopy and quantum calculation based on molecular modeling. DSC and FTIR experiments indicated that THP could be more easily incorporated into the DSPC bilayers, whereas the-NH3+ of THP might have much stronger interactions with the PO2- in the polar head of DSPG. The quantum calculation part is to investigate the interaction between-NH3+ of THP and PO2- of phospholipids from the molecular dynamics perspective. The Eint value of the interaction between-NH3+ of THP and PO2- of phospholipids can not only reflect the thermodynamic stability, but also probe that the implying mechanism is closely related to the unique structure of the polar heads. The strong interaction between THP and the polar head of DSPG could prevent or inhibit the further penetration of THP into its bilayers; therefore, the bilayer mobility could not be easily changed.A novel pirarubicin liposome powder (L-THP), comprising DSPC, DSPG, cholesterol and lactose, was appropriately prepared based on the unique physico-chemical properties of THP. The new preparation method has huge market prospective for its simple operation and good repeatability in the production. Meanwhile, the mechanism was well elucidated. Furthermore, the preparing process and formulations of L-THP were optimized.In vitro and in vivo assay of pirarubicin were established and the corresponding analytical method were validated. Pharmacokinetic studies showed that the accumulation of THP in the heart could be greatly reduced in our L-THP. Meanwhile, it tended to accumulate in the spleen and lung. Meanwhile, there is a quick clearation of THP in the L-THP. Although the bioavability of THP in the plasma was relatively a bit lower than that of marketed pirarubicin injection, the overall bioavability could be significantly improved.Safety mechanism of L-THP was investigated through the studies of enzyme activity, pathological and metabonomics. Results of weight, daily behavior, enzyme activity and pathological studies showed that the myocardial damage degree of THP could be greatly reduced when encapsulated into the liposomes. Metabonomics study of urine samples suggested that there were potential biomarkers closely related with the cardiotoxicity of pirarubicin:pirarubicin can generate ROS as well as the aglycones, thus inducing the acute cardiotoxicity; C-13 alcohol metabolites through the two-electron reduction may gain chronic cardiotoxicity. It further suggested that L-THP would have less cumulative cardiotoxicity since the content of biomarkers was low. This phenomenon should be attributed to the consequence of low accumution and high clearation rate of THP.