When biosimilars are registered as different strengths
Question:
Why are some brands of trastuzumab intravenous formulation labelled as 440 mg per vial whereas some as 420 mg per vial? Are there any differences in the strength of the solution after reconstitution?
Answer:
440 mg per vial refers to the nominal vial content whereas 420 mg per vial refers to the actual withdrawable amount when reconstituted in accordance with the directions in the approved package inserts. There is no difference after reconstitution, which yields a solution containing 21 mg/ml of trastuzumab.