Bendamustine pharmaceutical compositions

An oral solid dosage form comprising a spray-dried solid dispersion, wherein the spray-dried solid dispersion comprises a nitrogen mustard compound, or a pharmaceutically acceptable salt thereof, and one or more pharmaceutically acceptable excipients, diluents, or carriers, wherein the nitrogen mustard compound is selected from the group consisting of bendamustine, bestrabucil, chlorambucil, cyclophosphamide, diphenylspiromustine, spiromustine, melphalan, estramustine phosphate sodium, ifosfamide, mafosfamide, and prednimustine, wherein the spray-dried solid dispersion is substantially free of hydrolysis degradants of the nitrogen mustard compound, or a pharmaceutically acceptable salt thereof, and wherein the spray-dried solid dispersion comprises less than 8% by weight water.