Methods of efficiently treating vitamin C deficiency-related diseases and other conditions

The invention described here provides methods of efficiently treating vitamin C deficiency-related diseases and other conditions comprising the administration of pharmaceutical compositions comprising ascorbic acid compound(s), such as sodium ascorbate, and one or more pharmaceutically acceptable excipients (e.g., a carrier and optionally other agents, such as a tonicity agent, a chelator, or both). The methods comprise administration of such compositions in ready-to-use (RTU) form, provided in single unit dose packaging, wherein the compositions are stable when stored at 20° C. to 25° C.±2° C. for at least about 3 months. Compositions provided by the invention comprise an osmolality of between about 270 mOsm/kg to about 340 mOsm/kg and do not require dilution or further manipulation prior to use.