Background and importance Vancomycin eyedrops (VED) are unavailable in Europe and are usually compounded as extemporaneous in hospital pharmacies.

Aim and objectives To collect data on VED physicochemical stability in three different containers stored either refrigerated or frozen.

Material and methods VED at 50 mg/ml (10 mL) were aseptically compounded under a laminar flow hood from injectable vancomycin and sterile water for injection (Baxter) and stored in amber glass (n=26; Gravis), classical (n=26; CAT) or innovative Novelia (n=26; Nemera) low-density polyethylene (LDPE) bottles. Assays were performed according to GERPAC-SFPC stability studies guidelines on vials stored either at 2–8°C (analysis at days D1-D3-D7-D15-D40-D60-D90) or frozen at –20°C for 60 days, then thawed (room temperature (RT) or 2–8°C) and refrigerated once thawed (post-thaw analysis at D1-D3-D7-D20). At each time point in the study vancomycin concentration (using a stability-indicating HPLC-UV method), pH and osmolality were determined, and the visual aspect was checked. Sterility and non-visible particle count (by light obscuration particle count test) were performed at the beginning and end of the study. Non-parametric tests were used to compare containers and storage conditions (α=5%).

Results Vancomycin concentration (mean ± standard deviation; expressed as a percentage of the initial value) when stored at 2–8°C from D1 to D60 was between 95.7±1.6% and 107.4±2.1% (except at D7, due to material bias) and 89.5±1.6% and 92.8±1.9% at D90. Vancomycin concentration in vials thawed at RT or 2–8°C was, respectively, between 95.8±1.1% and 102.2±4.3% and 95.3±2.3% and 101.1±4.1% at D7 and between 89.3±1.8% and 93.9±0.6% and 89.9±0.8% and 92.7±1.2% at D20 after thawing. No significant difference was found between packaging (p=0.323) or thawing method (p=0.736). pH and osmolality, respectively, 3.31±0.06 and 46.12±3.61 mOsm/kg, remained stable with no difference between containers (p=0.242 and p=0.414) or thawing methods (p=0.287 and p=0.999). A slight yellow colouration of VED (2–8°C) was perceived after D60. A slight increase in non-visible particles count was observed between D1 and D90 in glass and classic LDPE but values complied with the European Pharmacopoeia 2.9.19 threshold.

Conclusion and relevance VED remained stable for 2 months refrigerated or frozen, and for 7 days after thawing (RT or 2–8°C). These results will allow the preparation of a stock of VED that is available immediately. A microbiological stability study in real conditions of use should complete this work.

Conflict of interest No conflict of interest