Sterilization of drugs using supercritical carbon dioxide sterilant

A drug sterilization method comprising (a) placing a drug in a micro-crystalline or powder form state in need of sterilization in a vessel with a sterilization enhancing effective amount of a chemical sterilization additive, (b) regulating a pressurization rate of the vessel to bring the drug into contact with a sterilant fluid comprised of carbon dioxide at or near the supercritical pressure and temperature conditions of said carbon dioxide, (c) maintaining said contact with the sterilant fluid under said temperature and pressure conditions for a time sufficient to achieve a 6-log reduction or greater in colony forming units (CFUs), and then (d) regulating a depressurization rate of the vessel such that depressurization occurs at a rate of 0.1-75 psi per second until ambient operating conditions are reached, whereby by regulating the pressurization and depressurizations rates, the state of the drug remains unchanged.