Pfizer Questions Drug ‘Total Content’ in Biosimilar Guidance

Pfizer asked the FDA to clarify the term “total content” in its draft guidance for biosimilar development, for demonstrating that a drug and a reference product have the same strength.

The guidance explains that sponsors can show a product has the same strength as its reference product “by demonstrating that both products have the same total content of drug substance (in mass or units of activity).” But Pfizer wants to know if “total content” refers to the net quantity content noted on the drug label or the net quantity including any additional overfill.

In most cases, Pfizer said, the total content for a drug, including drug substance overfill, isn’t known because the amount of overfill is not normally posted in the USPI or other sources of public information. But most products must contain some overfill to meet the net quantity claimed on the label.