Stability of bevacizumab divided in multiple doses for intravitreal injection

Objective: To investigate the stability of bevacizumab in multiple doses divided from a single-use vial for intravitreal injection after storage at 4°C for up to six months and under drug transfer condition in tropical climate. Material and Method: Five syringes (0.1 mL, 2.5 mg) of bevacizumab were withdrawn each from five new bevacizumab single-use vials (4 mL, 100 mg) under sterile technique. The concentration of bevacizumab in each syringe was measured at two dilutions (2x10⁶ and 4x10⁶ fold) using enzyme-linked immunosorbent assay at baseline and after storage at 4°C for 1-, 3-, and 6-month. Each assay was performed at least twice. To simulate the drug transfer condition, bevacizumab was placed in a brown plastic bag and put in another transfer plastic bag with an ice cube for 30 minutes prior to the assay at 1-, 3-, and 6-month. Results: The concentrations of bevacizumab (mean ? standard deviation) at baseline, 1-, 3-, and 6-month were 26.24±1.95, 25.43±3.80, 27.87±2.81, and 24.25±2.00 mg/mL, respectively. The lowest lower limit of 95% confidence interval for the mean concentration was 23.32 mg/mL at 6-month storage, which was 89% of the mean baseline concentration and considered to be non-inferior to the baseline concentration. Conclusion: Bevacizumab in a single-use vial could be divided into multiple small doses for intravitreal injection with sufficient stability when refrigerated at 4°C for up to six months and under the drug transfer condition in tropical climate.