Influence of temperature on the thirty-day chemical stability of extemporaneously prepared dexamethasone paste.

Dexamethasone, a high-potency synthetic glucocorticoid, is often used to treat various immunological and inflammatory conditions. Commercial preparations of dexamethasone facilitate administration to human patients. Veterinary use of dexamethasone may be complicated by the unavailability of commercial dosage forms. As such, compounded preparations containing dexamethasone, such as a topical paste, are used in veterinary medicine. The purpose of this study was to determine the 30-day stability of compounded dexamethasone 2 mg/mL paste when incubated in temperatures which may mimic storage conditions during any given season. Samples were incubated at room temperature, -20 degrees C, 4 degrees C, 40 degrees C, and 80 degrees C for 30 days. Samples were subsequently analyzed using a stability-indicating high-performance liquid chromatography method on a reverse phase column. Our data suggests that the chemical stability of dexamethasone, the active pharmaceutical ingredient, is well within the guidelines set forth in United States Pharmacopeia Chapter <795> (90% to 110% stated potency) for all tested temperatures, with the exception of 80 degrees C (approximately 176 degrees F).