Chemical Stability of Lorazepam Oral Solution Repackaged in Plastic Oral Syringes at Room and Refrigerated Temperature

Abstract

Purpose: Generic lorazepam oral solution is supplied in a 30 mL multi-dose bottle requiring protection from light and refrigeration, with a beyond use date of 90 days once the bottle is opened. The repackaging of 1 mL doses of lorazepam oral solution into oral syringes allows for facilitated dispensing, yet no available data supports repackaging and storing lorazepam oral solution in syringes. The validation and application of a stability-indicating high-performance liquid chromatography with ultraviolet detection (HPLC-UV) method for the quantification of lorazepam allowed for the determination of the stability of lorazepam oral solution when stored in oral syringes. Methods: A stability-indicating HPLC-UV method was developed for the quantification of lorazepam in oral solution. The method was validated using guidance from USP < 1225 >. For the stability investigation, 2 mg/mL lorazepam oral solution was aliquoted into clear plastic oral syringes in 1 mLmilliliter doses from 2 multi-dose stock bottles and randomly allocated for storage in room temperature or refrigerated environment. Baseline lorazepam concentrations were measured on the day the study was initiated and designated as 100% initial concentration samples. Subsequent samples were analyzed in triplicate at time points of 24, 48, and 96 hours and 7, 10, 14, 21, 30, and 60 days. Results: The calibration curves on three non-consecutive days met the linearity criteria of R² > 0.99. Inter- day and intra-day precision and accuracy (percent relative standard deviation and percent error) were ≤2% over three days. During the stability investigation, percent initial concentration of lorazepam from room and refrigerated syringes remained above 90% for the duration of the study. Conclusion: The stability-indicating HPLC-UV method was successfully applied to the investigation of lorazepam oral solution stability when stored in syringes at room and refrigerated temperatures. The emergent need for use of lorazepam concentrate for inpatients and the restrictions of how the medication is supplied necessitated a need for the evaluation of repackaging into unit dose syringes for immediate availability from automated dispensing cabinets. Lorazepam oral solution stored in clear plastic syringes maintained greater than 90% initial concentration at both room and refrigerated temperatures for 60 days.