Compounded gabapentin for neuropathic pain: Stability and beyond-use date (BUD) in some commonly used bases.

OBJECTIVES: To investigate the stability and beyond-use date (BUD) of topical gabapentin in 3 commonly used bases.

METHODS: Lipoderm cream, Versabase gel, and Emollient cream were used to compound gabapentin (10%). The products were stored in Ecolojars, kept at 25°C, 4°C, and 40°C, and samples were collected on different days (days 0, 14, 28, and 90). Potency, stability, and organoleptic changes were monitored.

RESULTS: At 25°C and 40°C, the potency of gabapentin in Lipoderm cream significantly increased (P < 0.05) after 28 and 90 days, respectively. In contrast, gabapentin degraded in Emollient cream (P < 0.05). At 25°C, the organoleptic properties of the drug compounded with Lipoderm cream (25°C) remained consistent for up to 28 days but showed signs of physical changes in other bases. Gabapentin recrystallized from Versabase gel and Emollient cream within 14 days.

CONCLUSION: Gabapentin compounded with Lipoderm cream for topical use was stable in Ecolojars for 28 days at 25°C. Under the same conditions, the drug was not stable in Versabase gel and Emollient cream. Based on our stability and potency data, the beyond-use date of currently dispensed gabapentin (10%) formulations with Lipoderm cream should not be extended beyond the currently assigned 30-day mark, even when refrigerated. It is unclear whether the stability of these formulations is improved if stored in air-tight containers.