What is Darbepoetin Alfa Polysorbate?
Darbepoetin alfa polysorbate is a formulation of darbepoetin alfa (Aranesp) that contains polysorbate 80 as an excipient—a synthetic nonionic surfactant used to stabilize and solubilize the protein in the injectable solution. 1
Formulation Details
Darbepoetin alfa is an erythropoiesis-stimulating protein produced through recombinant DNA technology in Chinese hamster ovary (CHO) cells. It differs from recombinant human erythropoietin by containing 5 N-linked oligosaccharide chains instead of 3, resulting from amino acid substitutions in the peptide backbone. The molecular weight is approximately 37,000 daltons. 1
The polysorbate-80 containing formulation (Aranesp injection) is a sterile, colorless, preservative-free solution containing: 1
- Polysorbate 80: 0.05 mg per mL
- Sodium chloride: 8.18 mg per mL
- Sodium phosphate dibasic anhydrous: 0.66 mg per mL
- Sodium phosphate monobasic monohydrate: 2.12 mg per mL
- Water for Injection, USP (pH 6.2 ± 0.2)
Role of Polysorbate 80
Polysorbate 80 serves as a solubilizing agent and stabilizer in the formulation, preventing surface loss and protein aggregation. Research demonstrates that polysorbate 80 interacts with the darbepoetin alfa protein structure, inducing alpha-helix formation and affecting the protein's biophysical properties in a concentration-dependent manner. 2
Clinical Context
This formulation is approved for intravenous or subcutaneous administration in:
- Adult and pediatric patients with chronic kidney disease (CKD) for anemia treatment 1
- Adult patients with chemotherapy-induced anemia 3, 4
Important Safety Consideration: While polysorbate 80 is generally considered an inert excipient, it has been associated with hypersensitivity reactions, injection-site adverse events, and nonimmunologic anaphylactoid reactions in some patients. 5, 6, 7 These reactions are not specific to darbepoetin alfa but relate to the polysorbate 80 component itself, particularly macromolecular impurities within the excipient. 7
The polysorbate-80 formulation should be distinguished from any polysorbate-free alternatives that may become available, as the excipient profile can affect both tolerability and the risk of infusion-related reactions.