Formulation development of frozen parenteral dosage forms.

Many of the intravenously administered drug compounds are formulated as frozen dosage forms due to lack of sufficient chemical stability at room or refrigerated temperatures. The product is stored in a freezer in the hospital pharmacy and thawed prior to its use. These products therefore, require a long-term frozen shelf-life plus a short-term room temperature and/or refrigerated temperature shelf-life. The formulation is optimized for overall stability in the frozen state as well as in the thawed state. In this paper, the significance of phase changes in the frozen state and the influence of various formulation factors such as drug concentration, diluent, buffer concentration, pH, and raw material purity on the drug stability in the frozen state is reviewed. An overview of analytical and manufacturing considerations unique to frozen products is also presented.