Filgrastim, marketed under brand names like Neupogen, Nivestym, and Nypozi, is a medication that functions as a granulocyte colony-stimulating factor (G-CSF). It is used to stimulate the bone marrow to produce more white blood cells (specifically neutrophils) to fight infection, often after a cycle of chemotherapy. While not known for a vast number of interactions compared to some other drugs, the few that exist are critical for safe use. These interactions primarily involve other medications, specific health conditions, and timing related to cancer treatment.
Important Drug Interactions
Cytotoxic Chemotherapy
The most critical interaction for filgrastim involves its timing relative to chemotherapy. Because filgrastim stimulates the growth of new myeloid cells (including neutrophils), and chemotherapy agents target and kill rapidly dividing cells, giving filgrastim too close to chemotherapy can render the chemotherapy less effective.
- The 24-Hour Rule: Filgrastim should not be administered in the period starting 24 hours before and ending 24 hours after a dose of cytotoxic chemotherapy. This specific timing window is vital to protect the new blood cells from being destroyed by the chemotherapy.
Certain chemotherapy drugs have been noted to interact in specific ways with filgrastim, potentially increasing the risk or severity of adverse effects:
- Bleomycin and Cyclophosphamide: Combining filgrastim with these drugs may increase the risk of pulmonary toxicity.
- Topotecan: Concurrent use can increase the risk of neutropenia.
- Vinca Alkaloids (Vinblastine, Vincristine, Vindesine, Vinorelbine): Use with these drugs may increase the risk of peripheral neuropathy.
Lithium
Lithium is another medication that can interact with filgrastim. Both drugs have a myeloproliferative effect, meaning they can stimulate the bone marrow to produce white blood cells.
- Potentiation: Caution is necessary when using filgrastim and lithium concurrently, as the combination can lead to an excessive increase in white blood cell counts (leukocytosis).
- Monitoring: If a patient is taking both medications, their doctor may require more frequent complete blood counts (CBCs) to monitor for an overproduction of white blood cells.
Significant Disease Interactions
Filgrastim use is contraindicated or requires significant caution in patients with specific medical conditions due to the risk of exacerbating symptoms or causing severe complications.
- Sickle Cell Disease: Severe and potentially fatal sickle cell crises have been reported in patients with sickle cell disease receiving filgrastim products. The risks and benefits must be carefully weighed before starting therapy in these individuals.
- Myeloid Tumors: As a G-CSF, filgrastim can theoretically enhance the growth of myeloid tumors. It should be used cautiously in patients with myeloproliferative disorders or other myeloid malignancies.
- Glomerulonephritis: Filgrastim may cause or worsen glomerulonephritis, a condition affecting the kidneys. Patients with existing renal dysfunction or symptoms of glomerulonephritis (swelling, dark urine) should be closely monitored.
- Sepsis: In septic patients, filgrastim can increase the influx of neutrophils, theoretically increasing the risk of acute respiratory distress syndrome (ARDS). Respiratory status should be carefully monitored.
- Thrombocytopenia: While often mild, filgrastim can occasionally lower platelet counts. It should be used with caution in patients with pre-existing thrombocytopenia, and frequent blood counts are recommended.
- Leukocytosis: As filgrastim's purpose is to increase white blood cell counts, it should not be used in patients who already have an excessive number of white blood cells.
Food, Alcohol, and Supplements
- Food: There are no known interactions between filgrastim and food. Some sources recommend taking it on an empty stomach, while others recommend taking it with food. The most important thing is to maintain a healthy, balanced diet during treatment.
- Alcohol: There are no known direct interactions between filgrastim and alcohol. However, because filgrastim is often used alongside chemotherapy, and alcohol can worsen the side effects of many chemotherapy agents, limiting or avoiding alcohol is often advised.
- Dietary Supplements: Patients should inform their doctor about all dietary supplements, vitamins, and herbal products they are taking. The safety and efficacy of many of these with filgrastim and cancer treatment, in general, are not well-established.
Managing Filgrastim Interactions: A Comparison Table
| Interactive Agent | Interaction Type | Risk Profile | Management Strategy |
|---|---|---|---|
| Cytotoxic Chemotherapy | Critical Timing | High risk of reduced chemotherapy efficacy and potential toxicity | Do not administer within 24 hours before or after chemotherapy. |
| Lithium | Pharmacodynamic | Moderate risk of exaggerated myeloproliferation (leukocytosis) | Use with caution and increase frequency of blood count monitoring. |
| Sickle Cell Disease | Disease State | High risk of severe and potentially fatal sickle cell crisis | Careful risk-benefit assessment before use; close monitoring is required. |
| Myeloid Tumors | Disease State | Moderate risk of stimulating tumor growth | Use with caution; potential for tumor cells in progenitor cell collection. |
| Sepsis | Disease State | Moderate risk of acute respiratory distress syndrome (ARDS) | Monitor respiratory status closely during treatment. |
| Food | No Known | Low risk | No known interaction; follow general healthy eating guidelines. |
| Alcohol | Indirect | Low to moderate risk, especially with concurrent chemotherapy | No direct interaction, but may worsen chemotherapy side effects; moderation often recommended. |
Conclusion
While filgrastim is a vital tool for preventing infection during chemotherapy, understanding its interactions is critical for safe and effective use. The most important takeaways for patients and caregivers include strict adherence to the 24-hour separation rule from chemotherapy administration, informing healthcare providers about all other medications including lithium, and disclosing any pre-existing conditions like sickle cell disease or myeloid tumors. Thorough communication with your oncology team about your complete health history and medication list is the best defense against potential interactions and helps ensure the best possible treatment outcome. For more detailed information on specific product formulations, refer to the manufacturer's official documentation.
Visit the NCBI Bookshelf for in-depth information on Filgrastim in StatPearls.
