Long-term stability of esketamine in polypropylene syringes at 5 ± 3°C.

Objective: Esketamine (Vesierra) is a molecule, used alone or in combination, to induce and maintain general anaesthesia and to relieve pain in emergency medicine. The aim of this study is to evaluate the long-term physicochemical stability of a 1 mg/mL solution of esketamine diluted in 0.9% sodium chloride (NaCl) and stored in polypropylene syringes at 5±3°C during 65 days (64+1 day at 22±3°C) and 72 hours at 22±3°C (room temperature), in order to centralise preparation under aseptic conditions in hospital pharmacy.

Methods: Ten syringes were prepared under aseptic conditions. Five syringes were stored at 22±3°C for 3 days, and the five others were stored at 5±3°C for 64 days (+ 1 day at room temperature). The stability was periodically investigated. Particle appearance or colour changes were checked by visual inspection. A research of crystals was performed under the microscope. pH was followed to assess its stability. The turbidity of the solutions was estimated by a measure of optical densities at 350, 410 and 550 nm. The molecule concentrations were measured by ultra-high performance liquid chromatography (UHPLC) coupled with a photodiode array detection (PDA), using a newly developed method.

Results: Based on microscopic examination, no crystals were observed, during the observation period. pH and absorbances at 350, 410 and 550 nm were also stable. Macroscopically, there was no change in colour and appearance of opacity, turbidity or precipitation. Statistical analysis indicates that 1 mg/mL esketamine solutions were chemically stable under these conditions, given that less than 5% of the solutions have lost more than 10% of their initial content during the study based on the prediction interval.

Conclusions: One mg/mL solutions of esketamine hydrochloride are physically and chemically stable after production, for at least 72 hours at 22±3°C and 64 days at 5±3°C (+ 1 day at room temperature).