The long-term stability of CT-P6 biosimilar trastuzumab (Herzuma®, Biogaran Laboratories) has been studied in their vials after reconstitution of the lyophilized powder (21 mg/mL) and after dilution for final concentrations of 0.8 mg/mL and 2.4 mg/mL in polyolefin bags, all at 4°C and 22°. The physical and chemical stability has been evaluated by several orthogonal and complementary stability-indicating methods.
At 4°C for 28 days, no sign of instability was observed for all the tested parameters. After 90 days of storage at 4°C and 22°C, regardless of the antibody concentration, no sign of physical instability, such as formation of neither sub-visible or visible aggregates nor oligomers, was observed. After 90 days at 4°C, there was no change in the distribution of the 7 ionic variants. However, large signs of desamidation by hydrolysis were noticed after 28 days at 22°C. The tertiary high-order structure was unaltered after 28 days at 4°C but slightly modified at 22°C, but without sign of strong thermodynamic destabilization.
These results strongly support the safe use of this biosimilar trastuzumab in some practical situations such as preparation in advance, dose-banding, re-use of un-administered drug or cold-chain rupture, in order to improve the management of the patient, the nurse and the pharmacy workload and also to avoid non-justified losses of this expensive drug.
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