Extending the Shelf Life of Doxorubicin Loaded PLGA Nanoparticles with Cryoprotectants

Sugars, as cryoprotectants, can be added to NP formulations before lyophilization to ensure that NPs retain their size during long-term storage. In this study, mannitol, glucose, and sucrose were used at different concentrations to extend the storage time of doxorubicin (DOX)-loaded PLGA-NPs prepared using two different copolymer ratios (75 : 25 and 50 : 50) at different storage temperatures (-20, +4, and +25 degrees C). After lyophilization, a glucose or sucrose concentration of only 5 % for DOX-PLGA-75 : 25-NP and a glucose concentration of 10 % for DOX-PLGA-50 : 50-NP were found to prevent agglomeration for up to 4 months at -20 degrees C. It is noteworthy that after storage at 4 degrees C for up to 4 months, agglomeration was prevented using 5 % sucrose and 10 % glucose in DOX-PLGA-50 : 50-NP and 10 % sucrose content in both NP types. On the other hand, as expected, no sugar type or concentration could prevent agglomeration during long-term storage of NPs at 25 degrees C. The sizes and encapsulation efficiencies (EE%) before lyophilization were 221.8 +/- 2.20 and 45.4 % for DOX-PLGA-50 : 50-NP and 221.5 +/- 1.31 and 48.7 % for DOX-PLGA-75 : 25-NP, respectively. Furthermore, the release profiles and encapsulation of DOX in both NPs were investigated by UV-Vis analyses. DSC analysis revealed that DOX was present in the free form and amorphous in the NPs. Consequently, PLGA copolymer ratios were found to have an impact on the long-term stability of DOX loaded PLGA lyophilizates, and DOX-loaded NPs prepared with PLGA 75 : 25 or PLGA 50 : 50 can be stored at -20 and +4 degrees C for up to 4 months when combined with appropriate sugar contents and concentrations, demonstrating the versatility of these materials.