Abstract: The present disclosure provides injectable pharmaceutical compositions including suspended particles in a liquid carrier, where the particles of the composition include a biopharmaceutical agent and a polyacrylamide-based copolymer. The inventors have demonstrated that particular polyacrylamide-based copolymers can be used as stabilizing excipients in particle formulations of biopharmaceutical agents, without interacting directly with the biopharmaceutical agent, or altering its pharmacokinetic properties. The pharmaceutical composition can be formulated for injection to a patient. Also provided is a syringe loaded with the injectable pharmaceutical composition, methods of administering via injection a therapeutically effective dose of a biopharmaceutical to a subject in need thereof, and methods of preparing a subject injectable pharmaceutical composition.