Stability of levetiracetam oral solution repackaged in oral plastic syringes

Abstract

The long-term stability of levetiracetam solution in oral syringes was investigated in order to define a suitable beyond-use date and demonstrate the feasibility of storing prepared syringes for extended periods as an alternative to commercial levetiracetam unit dose cups. Levetiracetam oral solution (100 mg/mL) was drawn into 1- and 10-mL amber polypropylene oral syringes. Triplicate samples of the syringe preparations were stored at refrigeration (2-8 °C) or room temperature (20-25 °C) and evaluated at monthly intervals for up to six months. At each time point, the samples were visually inspected and levetiracetam stability was assessed via pH measurement and high-performance liquid chromatography (HPLC). A short-term forced degradation study was conducted to confirm that the HPLC assay method was stability indicating. Over the six-month storage period, there was no significant change in either the visual appearance or pH of any of the levetiracetam samples. The results of serial HPLC assessment indicated that at least 97% of the initial levetiracetam concentration was retained in all samples of 1- and 10-mL oral syringes at both refrigeration and room temperature. Although this study was conducted using a generic product, the stability data obtained may be applied in repackaging decisions regarding other generic formulations of levetiracetam with similar excipient compositions. Commercial levetiracetam 100-mg/mL oral solution was stable for up to six months in amber polypropylene oral syringes stored at both refrigeration and room temperature conditions.