What is the Difference Between Filgrastim and Pegfilgrastim?

Filgrastim and Pegfilgrastim are both recombinant human granulocyte colony-stimulating factors (G-CSF) that stimulate the growth and activation of neutrophils, a type of white blood cell. However, there are some differences between the two:

1. chemical modification: Pegfilgrastim is a chemically modified derivative of filgrastim, where a polyethylene glycol (PEG) molecule is attached to the protein, altering its pharmacokinetics and reducing its immunogenicity.
2. pharmacokinetics: Pegfilgrastim has an extended half-life, allowing for one injection per cycle of chemotherapy rather than the daily dosing required for filgrastim.
3. approved uses: Unlike filgrastim, pegfilgrastim is only approved for the prevention and treatment of febrile neutropenia. Filgrastim is also approved for peripheral stem cell mobilization for transplantation and for use in patients with myeloid cancers.
4. administration: Filgrastim is administered daily for up to a maximum of 14 days, either subcutaneously or intravenously, while pegfilgrastim is typically given as a subcutaneous injection.
5. effectiveness: A study comparing the effectiveness of prophylactic single fixed dose of pegfilgrastim and daily administration of filgrastim found that patients receiving pegfilgrastim had a significantly lower rate of severe neutropenia, as well as dose reduction and treatment delay, thus achieving a higher dose density.
6. cost-effectiveness: Pegfilgrastim is generally more effective than filgrastim as prophylaxis for febrile neutropenia (FN), but its usage has been limited due to its higher cost.

Comparative Table: Filgrastim vs Pegfilgrastim

Filgrastim and Pegfilgrastim are both medications used to stimulate white blood cell production in patients undergoing chemotherapy, but they have some differences. Here is a table comparing the two:

Both drugs are injected under the skin and stimulate the bone marrow to produce more white blood cells to fight against infections. However, Pegfilgrastim is a longer-acting form of Filgrastim, which means it has a longer duration of action and may require fewer injections. Despite its lower effectiveness, Filgrastim has been found to be more cost-effective in some cases due to its lower costs compared to Pegfilgrastim.