The invention provides compositions, kits, and methods for treatment of neuronal injury. In one embodiment, the composition comprises a biomembrane sealing agent, such as PEG, and a bioactive agent, such as a magnesium compound. The biomembrane sealing agent and/or the bioactive agent an intravenous administration, an intramuscular administration, an intrathecal administration, a subcutaneous administration, an epidural administration, a parenteral administration, a direct application onto or adjacent to a site of the pathological condition, and any combinations thereof. Alternatively, the biomembrane sealing agent and/or the bioactive agent may be delivered from a pump or an implant.