Preparation of etoposide injection concentrated at 10 mg/mL: Interest and physicochemical stability study

High-dose etoposide (VP16) at 60 mg/kg combined with total body irradiation is one of the myeloablative conditioning agents used in pediatric patients with hematological malignancies. The physico-chemical stability data for diluted VP16 stored at room temperature available from the manufacturer and in the literature are respectively 24 hours for a concentration of [0.2-0.4] mg/mL and 28 days for a concentration of 0.38-1.75 mg/mL. The administration of high doses therefore requires dilution of VP16 in a large volume, which is incompatible with administration to children.
The aim of this study was to determine the physico-chemical stability of VP16 injectable solutions at 10mg/mL in bags of 0.9% sodium chloride (NaCl0.9%) and 5% glucose (G5%).

Six bags of VP16 diluted to 10mg/mL in both G5% (n=3) and NaCl0.9% (n=3) Freeflex^® (Fresenius Kabi) were produced by aseptic transfer in a closed system using Etoposide MYLAN 200mg/10mL (VIATRIS), then stored at room temperature according to our pharmacy procedures. VP16 content was determined by HPLC-DAD (Thermofisher) using a stability-indicating assay validated to ICHQ2R1. VP16 forced degradation tests were carried out in accordance with GERPAC recommendations. pH measurements were carried out using a pH meter (EDGE pH, HANNA) and osmolarity measurements using a calibrated osmometer (OSMO1, Radiometer). Content, appearance of degradation products, macroscopic appearance (absence of precipitate, color change) and pH were determined immediately after preparation (D0), then over time at D1, D4, D7 and D14. The osmolarity of samples diluted 1/10th in PPI water was determined at D1 and D7.

The HPLC-DAD stability-indicating assay developed was linear, precise, repeatable, accurate and specific. The coefficients of variation repeatability and intermediate precision were below 5%. No matrix effects were observed. Loss of VP16 content did not exceed 5% up to D14, and no degradation impurities were detected. The pH values were respectively 3.8 at D0 and 3.9 at D14 in 0.9% NaCl and 4.3 at D0 and 4.1 at D14 in G5%. The osmolarity estimated from PPI dilution was 4550 mOsm/kg H2O at D1 and 4610 mOsm/kg H2O at D7 in 0.9% NaCl. In G5%, osmolarity was 4410 mOsm at D1 and 4440 mOsm/kg H2O at D7. No change in macroscopic appearance was noted over the study period.

This work has demonstrated the 7-day physicochemical stability of VP16 diluted to 10 mg/mL, hyperosmolar solutions in bags of 0.9% sodium chloride and 5% glucose. This will make it possible to limit fluid intake during high-dose etoposide graft conditioning in pediatrics.

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