Purpose: The stability of extemporaneously compounded diltiazem hydrochloride infusions stored in polyolefin bags was studied.
Methods: Sterile preparations of diltiazem hydrochloride were compounded to a concentration of 1 mg/mL in 5% dextrose solutions in accordance with United States Pharmacopeia chapter 797. The infusions were stored at -20 °C, 2-6 °C, and 22-25 °C. Three samples from each temperature were withdrawn and assessed for stability immediately after preparation (day 0) and on days 7, 15, 21, and 30 using a high-performance liquid chromatography (HPLC) assay. The physical stability of diltiazem samples was assessed by visual examination. Infusions were evaluated against black and white backgrounds for evidence of visible particulate matter, cloudiness, and color changes. The concentration of diltiazem hydrochloride in all samples was examined using a stability-indicating HPLC method at each time point. Diltiazem was considered stable if the solution retained over 90% of the initial concentration.
Results: No precipitation, cloudiness, or color change was observed at any of the temperatures studied. pH did not significantly increase or decrease among the samples, regardless of temperature, over the study period. The diltiazem hydrochloride infusions retained greater than 90% of the initial concentrations for at least 30 days.
Conclusion: Diltiazem hydrochloride diluted to 1 mg/mL in 5% dextrose injection was stable for 30 days when stored at -20 °C, 2-6 °C, and 22-25 °C.