Bendamustine formulations

A method for preparing a stable lyophilized bendamustine composition for treating a condition in a subject in need thereof, comprising:

• 1) preparing a pre-lyophilization bendamustine composition consisting of bendamustine hydrochloride, an aqueous solvent selected from water, and an excipient;
• wherein the pre-lyophilzation bendamustine composition is prepared by the method comprising:
• mixing about 30 wt % to about 99.9 wt % by weight of an aqueous solvent with about 0.01 wt % to about 50 wt % by weight of an excipient in a first compounding vessel at a preset temperature between about −2° C. and about 15° C. until said excipient dissolves in said aqueous solvent;
• maintaining said mixed aqueous solvent and said excipient in said first compounding vessel at said preset temperature between about −2° C. and about 15° C.;
• adding about 0.01 wt % to about 90 wt % by weight of bendamustine hydrochloride to about 5 wt % of a chilled aqueous solvent in a second compounding vessel until a uniform slurry is formed;
• adding said uniform slurry to said first compounding vessel containing said mixed aqueous solvent and said excipient maintained at said preset temperature between about −2° C. and about 15° C. and mixing contents of said first compounding vessel until said contents dissolve completely;
• adjusting said contents of said first compounding vessel to a final weight using an aqueous solvent chilled at a preset temperature between about −2° C. and about 15° C.;
• and
• filtering said adjusted contents in said first compounding vessel through a filter membrane
• 2) lyophilizing the above prepared pre-lyophilization bendamustine composition to obtain a lyophilized bendamustine composition
• 3) reconstituting the lyophilized bendamustine composition with an aqueous solvent for about 30 seconds to 300 seconds, wherein the reconstituted bendamustine product contains about 0.2 wt % to about 2.5 wt % by weight of impurities and the bendamustine solution is stable for 24 hours when stored at about 2° C. to about 8° C., or stable for 3 hours when stored at room temperature, at about 15° C. to about 30° C. under room lighting.