According to the FDA (2024), Filgrastim biosimilars like Zarxio are highly similar to Neupogen with no clinically meaningful differences in safety or potency.
A meta-analysis published in the Journal of Clinical Oncology (2022) confirmed that G-CSF significantly reduces the risk of infection-related mortality in patients with febrile neutropenia.
The American Society of Clinical Oncology (ASCO) guidelines (2023) recommend the use of filgrastim when the risk of febrile neutropenia is 20% or higher based on the chemotherapy regimen.
Data from the National Institutes of Health (NIH) indicates that filgrastim's elimination half-life is approximately 3.5 hours in both adult and pediatric populations.
The World Health Organization (WHO) includes filgrastim on its List of Essential Medicines, highlighting its critical role in modern cancer care.
Clinical trials reported in the New England Journal of Medicine showed that filgrastim reduced the duration of severe neutropenia from 6 days to 2 days in patients receiving chemotherapy for small-cell lung cancer.
According to DailyMed (2024), splenic rupture is a rare but documented risk, necessitating immediate evaluation for left upper quadrant abdominal pain.
Research published in 'Blood' (2021) suggests that filgrastim-induced bone pain is mediated by the release of histamine and other inflammatory markers within the bone marrow cavity.
This page is for informational purposes only and does not replace medical advice. Before using any prescription or over-the-counter medication for Releuko, you must consult a qualified healthcare professional.
Filgrastim is a recombinant granulocyte colony-stimulating factor (G-CSF) used to stimulate the production of white blood cells (neutrophils) in patients with cancer, bone marrow transplants, or chronic neutropenia.
💊Usage & Dosage
Adult Dosage
The dosage of filgrastim is highly individualized and is typically based on the patient's body weight (measured in kilograms) and the specific condition being treated.
Myelosuppressive Chemotherapy: The recommended starting dose is 5 mcg/kg/day, administered as a single daily subcutaneous injection or as a short intravenous infusion (15 to 30 minutes). Doses may be increased in increments of 5 mcg/kg for each chemotherapy cycle, depending on the duration and severity of the absolute neutrophil count (ANC) nadir (the lowest point).
Bone Marrow Transplant: The recommended dose is 10 mcg/kg/day given as an intravenous infusion of 4 or 24 hours, or as a continuous subcutaneous infusion of 24 hours. During the period of neutrophil recovery, the daily dose is titrated based on the ANC response.
Severe Chronic Neutropenia:
Congenital Neutropenia: Starting dose is 6 mcg/kg twice daily.
Idiopathic or Cyclic Neutropenia: Starting dose is 5 mcg/kg as a single daily dose.
Peripheral Blood Progenitor Cell (PBPC) Collection: The recommended dose is 10 mcg/kg/day, given subcutaneously, either as a single daily injection or as a divided dose. It is typically administered for at least 4 days before the first leukapheresis procedure and continued until the last leukapheresis.
Pediatric Dosage
Filgrastim is FDA-approved for use in pediatric patients. The efficacy and safety profiles in children are generally similar to those observed in adults.
General Pediatric Dosing: For chemotherapy-induced neutropenia, the starting dose is usually 5 mcg/kg/day, similar to adult dosing.
Severe Chronic Neutropenia in Children: Long-term daily administration is required. Pediatric patients with congenital neutropenia may require chronic daily doses to maintain an adequate ANC. Healthcare providers will monitor growth and development closely during long-term therapy.
Dosage Adjustments
Renal Impairment
Studies in patients with severe renal impairment (creatinine clearance < 30 mL/min) show that while the pharmacokinetic profile is altered, dosage adjustments are generally not required. However, close clinical monitoring is advised.
Hepatic Impairment
There are no specific dosage adjustment guidelines for patients with hepatic (liver) impairment, as the liver is not the primary organ for filgrastim clearance.
Elderly Patients
Clinical trials included a limited number of patients aged 65 and over. Generally, no overall differences in safety or effectiveness were observed between these patients and younger patients, and no specific dose adjustments are routinely recommended for the elderly, though individual sensitivity cannot be ruled out.
How to Take Filgrastim
Filgrastim is administered by injection. If you are using this medication at home, your healthcare provider will train you or your caregiver on the proper technique.
Preparation: Remove the vial or prefilled syringe from the refrigerator and allow it to reach room temperature for about 30 minutes before injecting. Do not shake the medication; shaking can denature the protein and make it ineffective.
Inspection: Check the liquid in the vial or syringe. It should be clear and colorless. Do not use it if it is cloudy, discolored, or contains particles.
Injection Sites: Common sites for subcutaneous injection include the outer area of the upper arms, the abdomen (avoiding the 2-inch area around the navel), and the front of the middle thighs. Rotate injection sites daily to prevent skin irritation.
Storage: Store filgrastim in the refrigerator at 36°F to 46°F (2°C to 8°C). Keep it in its original carton to protect it from light. Do not freeze it. If a vial or syringe is accidentally frozen, thaw it in the refrigerator, but if it is frozen a second time, discard it.
Missed Dose
If you miss a dose of filgrastim, contact your healthcare provider immediately for instructions. It is crucial to maintain the schedule prescribed by your doctor to ensure your white blood cell counts remain stable. Do not double the dose to catch up.
Overdose
The maximum tolerated dose of filgrastim has not been determined. In the event of an overdose, the primary concern is an excessive increase in white blood cell counts (leukocytosis), which can lead to complications. If an overdose is suspected, seek emergency medical attention or contact a poison control center immediately. Symptoms might include severe bone pain or respiratory distress.
> Important: Follow your healthcare provider's dosing instructions. Do not adjust your dose or stop the medication without medical guidance, as this could increase your risk of infection.
⚠️Side Effects
Common Side Effects (>1 in 10)
The most frequently reported side effect of filgrastim is medullary bone pain. This occurs because the bone marrow is rapidly expanding and producing new cells.
Bone Pain: This is typically described as a dull ache or throbbing sensation, most commonly felt in the lower back, hips, or long bones of the arms and legs. It usually begins a few days after the first dose and often subsides after the medication is discontinued. Non-aspirin pain relievers like acetaminophen are often recommended by doctors to manage this.
Fever and Chills: Some patients may experience mild flu-like symptoms shortly after injection.
Skin Rash: Redness or itching at the site of injection is common and usually temporary.
Nausea and Vomiting: While often related to concurrent chemotherapy, filgrastim itself can contribute to gastrointestinal upset.
🔴Warnings
Important Safety Information
Filgrastim is a potent biological modifier. Before starting treatment, patients must be screened for pre-existing conditions that could be exacerbated by an increase in white blood cell production. It is vital to understand that filgrastim does not treat cancer itself; rather, it manages the side effects of cancer treatment or underlying bone marrow failure.
Black Box Warnings
No FDA black box warnings for Filgrastim. However, the risk of splenic rupture is a primary safety concern that patients must be educated on before the first dose.
Major Precautions
Allergic Reactions: Hypersensitivity, including anaphylaxis, has been reported. These reactions can occur with the first dose or subsequent doses. If a serious allergic reaction occurs, filgrastim must be permanently discontinued.
🔄Interactions
Contraindicated Combinations (Do Not Use Together)
There are no absolute drug-drug contraindications where filgrastim must never be used with another agent. However, the timing of administration is a critical contraindication in relation to chemotherapy.
Cytotoxic Chemotherapy: Filgrastim should NOT be administered in the period 24 hours before to 24 hours after the administration of cytotoxic chemotherapy.
Clinical Consequence: Because filgrastim stimulates rapidly dividing myeloid cells, and chemotherapy targets rapidly dividing cells, giving them simultaneously could make the newly produced white blood cells more vulnerable to the chemotherapy, potentially worsening the neutropenia rather than helping it.
Serious Interactions (Monitor Closely)
Lithium
🚫Contraindications
Absolute Contraindications
There are very few absolute contraindications for filgrastim, but they are critical for patient safety:
1Serious Allergic Reactions to Filgrastim or Pegfilgrastim: If a patient has a known history of systemic hypersensitivity (anaphylaxis) to filgrastim (Neupogen), any of its biosimilars (Zarxio, Nivestym, etc.), or the long-acting version (pegfilgrastim/Neulasta), they must never receive the drug again.
Mechanism: This is an IgE-mediated immune response that can lead to airway closure and cardiovascular collapse.
1Hypersensitivity to E. coli-Derived Proteins: Because filgrastim is manufactured using E. coli bacteria, patients with a known, severe allergy to proteins derived from this bacterium should not use filgrastim.
👥Special Populations
Pregnancy
Filgrastim is classified under FDA Pregnancy Category C (under the older system). There are no adequate and well-controlled studies in pregnant women. Animal studies have shown that filgrastim can cause embryo-fetal toxicity (increased pregnancy loss) at doses significantly higher than the human dose.
Clinical Consideration: Filgrastim should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. If a patient becomes pregnant while on filgrastim, they should notify their oncologist or hematologist immediately.
Breastfeeding
It is not known whether filgrastim is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when filgrastim is administered to a nursing woman. However, since filgrastim is a large protein, it is likely that any drug ingested by the infant via milk would be broken down by the infant's digestive enzymes and not absorbed in significant amounts.
Pediatric Use
🧬Pharmacology
Mechanism of Action
Filgrastim is a recombinant human granulocyte colony-stimulating factor (r-metHuG-CSF). It acts by binding to the G-CSF receptor (G-CSFR) on the surface of hematopoietic cells. This binding triggers the JAK-STAT signaling pathway, which leads to the production of transcription factors that promote the survival, proliferation, and differentiation of neutrophil lineages. It specifically targets the 'colony-forming unit-granulocyte' (CFU-G) to accelerate the production of mature neutrophils.
Pharmacodynamics
The primary pharmacodynamic effect of filgrastim is a dose-dependent increase in the absolute neutrophil count (ANC). After administration, there is an initial transient decrease in circulating neutrophils (due to margination), followed by a rapid increase. The neutrophils produced in response to filgrastim show normal or enhanced chemotactic and phagocytic function. The effect on the ANC is sustained as long as daily administration continues.
Pharmacokinetics
| Parameter | Value |
|---|---|
Frequently Asked Questions
Common questions about Releuko
What is Filgrastim used for?
Filgrastim is primarily used to treat or prevent neutropenia, a condition where the body has too few neutrophils (a type of white blood cell). It is most commonly prescribed to cancer patients receiving chemotherapy that suppresses the bone marrow. By increasing white blood cell counts, it helps reduce the risk of serious infections and hospitalizations. It is also used for patients undergoing bone marrow transplants and those with rare, chronic forms of neutropenia. Additionally, it helps move stem cells from the bone marrow into the blood for collection and future transplant.
What are the most common side effects of Filgrastim?
The most common side effect reported by patients is bone pain, which occurs as the bone marrow works harder to produce new cells. This pain is often felt in the back, hips, or legs and can usually be managed with over-the-counter pain relievers. Other frequent side effects include redness or swelling at the injection site, mild fever, and headaches. Some patients also report muscle aches or general fatigue. While these are common, they are usually temporary and stop once the treatment cycle is finished.
Can I drink alcohol while taking Filgrastim?
There is no known direct drug interaction between alcohol and Filgrastim. However, healthcare providers generally recommend limiting alcohol during cancer treatment or while recovering from bone marrow suppression. Alcohol can cause dehydration and may worsen side effects like headaches, nausea, or fatigue. It can also place extra stress on the liver, which is often already working hard to process other medications. Always consult your doctor about your specific alcohol consumption habits during treatment.
Is Filgrastim safe during pregnancy?
Filgrastim is generally only used during pregnancy if the potential benefits to the mother outweigh the risks to the fetus. Animal studies have suggested that high doses may lead to pregnancy loss, but there is limited data in humans. It is considered a Category C medication, meaning caution is required. If you are pregnant or planning to become pregnant, you must discuss this with your oncologist or hematologist. They will evaluate the severity of your neutropenia against the potential developmental risks.
How long does it take for Filgrastim to work?
Filgrastim begins to stimulate the bone marrow almost immediately after the first injection. However, a noticeable increase in the white blood cell count (ANC) typically takes 1 to 2 days to appear in blood tests. The peak effect usually occurs after several days of consistent daily dosing. Once the medication is stopped, the white blood cell count usually begins to drop within 24 to 48 hours. Your doctor will monitor your blood counts regularly to determine exactly how long you need to stay on the medication.
Can I stop taking Filgrastim suddenly?
Yes, Filgrastim can be stopped without a tapering process, as it does not cause a traditional 'withdrawal' syndrome. However, you should only stop taking it when directed by your healthcare provider. If you stop too early, your white blood cell count may drop back to dangerously low levels, increasing your risk of infection. Doctors typically wait until your blood counts have reached a specific target before ending the treatment. Always follow the exact schedule provided by your medical team.
What should I do if I miss a dose of Filgrastim?
If you miss a dose of Filgrastim, you should contact your doctor or nurse as soon as possible for guidance. Do not take two doses at once to make up for the missed one. The timing of Filgrastim is often carefully coordinated with your chemotherapy schedule, so missing a dose could impact your recovery timeline. Your healthcare provider will tell you whether to take the dose immediately or wait until the next scheduled time. Keeping a consistent daily schedule is the best way to ensure the drug's effectiveness.
Does Filgrastim cause weight gain?
Filgrastim is not typically associated with traditional weight gain from fat. However, a rare but serious side effect called Capillary Leak Syndrome can cause sudden swelling and fluid retention, which may show up as a rapid increase in weight on the scale. If you notice sudden puffiness in your face or limbs, or a quick weight jump over 24 hours, contact your doctor immediately. General weight changes during treatment are more often related to other medications, such as steroids, or changes in activity and diet.
Can Filgrastim be taken with other medications?
Filgrastim can be taken with many other medications, but timing is critical. It should not be given within 24 hours before or after receiving chemotherapy, as the two treatments can interfere with each other. It may also interact with Lithium, which can further increase white blood cell counts. You should provide your doctor with a complete list of all prescriptions, over-the-counter drugs, and herbal supplements you are taking. This allows them to screen for any potential issues before you start Filgrastim therapy.
Is Filgrastim available as a generic?
Filgrastim is available as several 'biosimilars,' which are effectively the biological version of generics. These include Zarxio (filgrastim-sndz), Nivestym (filgrastim-aafi), and Releuko (filgrastim-ayow). These biosimilars have been rigorously tested and proven to be just as safe and effective as the original brand-name drug, Neupogen. Using a biosimilar can often be more cost-effective for patients and insurance providers. Your pharmacy or hospital will dispense the version that is approved by your insurance plan and medical facility.
Similar Medications
Other drugs with the same active ingredient (Filgrastim)
Headache: Persistent or tension-type headaches may occur.
Joint Pain (Arthralgia): General aches in the joints without swelling.
Epistaxis (Nosebleeds): A slight increase in the frequency of nosebleeds has been noted in some clinical trials.
Thinning Hair (Alopecia): While primarily a result of chemotherapy, some patients report continued thinning while on growth factors.
Rare Side Effects (less than 1 in 100)
Splenomegaly: Enlargement of the spleen is rare but can occur, particularly in patients receiving long-term therapy for severe chronic neutropenia. Most cases are asymptomatic, but it requires monitoring via physical exam or ultrasound.
Sweet’s Syndrome: Also known as acute febrile neutrophilic dermatosis, this is a rare skin condition characterized by fever and painful, red skin lesions. It is thought to be an overreaction of the immune system.
Cutaneous Vasculitis: Inflammation of the blood vessels in the skin, which may appear as purple spots or 'palpable purpura' on the legs.
Serious Side Effects — Seek Immediate Medical Attention
> Warning: Stop taking Filgrastim and call your doctor immediately if you experience any of these serious symptoms.
1Splenic Rupture: This is a life-threatening complication. Symptoms include pain in the left upper stomach area or left shoulder tip pain. This requires emergency surgery.
2Acute Respiratory Distress Syndrome (ARDS): Filgrastim can cause lung inflammation. Seek help if you develop fever, shortness of breath, or a rapid breathing rate.
3Serious Allergic Reactions (Anaphylaxis): Symptoms include rash over the whole body, shortness of breath, wheezing, dizziness, swelling around the mouth or eyes, fast pulse, or sweating.
4Sickle Cell Crisis: In patients with sickle cell disorders, filgrastim can trigger a severe and sometimes fatal crisis.
5Capillary Leak Syndrome (CLS): This causes blood to leak from small blood vessels into body tissues. Symptoms include swelling or puffiness, urinating less often than usual, tiredness, and a sudden increase in weight.
6Glomerulonephritis: Kidney inflammation characterized by puffiness in the face/ankles, blood in the urine, or dark-colored urine.
Long-Term Side Effects
For patients on long-term therapy (such as those with Severe Chronic Neutropenia), there are specific concerns regarding the evolution of their condition. There is a risk of developing Myelodysplastic Syndrome (MDS) or Acute Myeloid Leukemia (AML). While it is difficult to distinguish whether this is caused by the underlying disease or the long-term use of filgrastim, patients on chronic therapy require regular bone marrow exams and blood counts to monitor for these changes.
Black Box Warnings
There are currently no FDA black box warnings for filgrastim. However, the warnings regarding splenic rupture and ARDS are considered highly significant and are prominently featured in the 'Warnings and Precautions' section of the prescribing information.
Report any unusual symptoms to your healthcare provider. Even mild side effects should be discussed, as your doctor may be able to adjust your supportive care plan to improve your comfort.
Splenic Rupture
: Cases of splenic rupture, including fatal cases, have been reported following the administration of filgrastim. Patients who report left upper abdominal or shoulder pain should be evaluated immediately.
Acute Respiratory Distress Syndrome (ARDS): ARDS is a severe lung condition that can be fatal. If a patient develops a cough, fever, and chest pain with shortness of breath, filgrastim should be withheld until ARDS is ruled out.
Alveolar Hemorrhage and Hemoptysis: Pulmonary hemorrhage (bleeding in the lungs) resulting in hemoptysis (coughing up blood) has been reported in healthy donors undergoing PBPC mobilization.
Capillary Leak Syndrome (CLS): CLS can occur and is characterized by hypotension (low blood pressure), hypoalbuminemia, edema, and hemoconcentration. This condition can be life-threatening if treatment is delayed.
Aortitis: Inflammation of the aorta has been reported. Symptoms include fever, abdominal pain, malaise, and back pain.
Nuclear Imaging: Increased hematopoietic activity of the bone marrow in response to growth factor therapy has been associated with transient positive bone-imaging findings. This should be considered when interpreting bone-imaging results.
Monitoring Requirements
Patients taking filgrastim require frequent medical monitoring:
Complete Blood Count (CBC): CBCs with differential (to count specific types of white cells) are typically performed twice weekly during therapy to monitor the ANC and ensure it does not exceed safe limits (e.g., keeping the ANC < 10,000/mm³).
Spleen Size: Periodic physical examinations or ultrasounds may be needed for patients on long-term therapy to check for an enlarged spleen.
Urinalysis: To monitor for signs of glomerulonephritis (kidney inflammation).
Driving and Operating Machinery
Filgrastim generally does not affect the ability to drive or operate machinery. However, if a patient experiences dizziness or significant bone pain, they should exercise caution until they know how the medication affects them.
Alcohol Use
There is no known direct interaction between alcohol and filgrastim. However, alcohol can dehydrate the body and may worsen certain side effects like headaches or nausea. Patients undergoing chemotherapy are generally advised to limit alcohol consumption to support overall health and liver function.
Discontinuation
Filgrastim is usually discontinued once the ANC has surpassed the expected nadir and has returned to an acceptable range (typically > 10,000/mm³). There is no 'withdrawal syndrome' associated with stopping filgrastim, but the white blood cell count will typically drop by 50% within 1 to 2 days of stopping the drug and return to baseline within 1 to 7 days.
> Important: Discuss all your medical conditions, especially any history of sickle cell disease or kidney problems, with your healthcare provider before starting Filgrastim.
: Lithium is known to stimulate the release of neutrophils from the bone marrow.
Mechanism: Pharmacodynamic synergy.
Clinical Consequence: If a patient is taking both lithium and filgrastim, the neutrophil count may rise much higher and more rapidly than expected.
Management: More frequent monitoring of white blood cell counts is required if these drugs are used together.
Moderate Interactions
Topical or Systemic Corticosteroids: Steroids can sometimes cause a temporary increase in white blood cell counts (leukocytosis).
Mechanism: Additive pharmacodynamic effect.
Clinical Consequence: May mask the true response to filgrastim or lead to excessively high white blood cell counts.
Other Growth Factors: Using filgrastim simultaneously with other colony-stimulating factors (like Sargramostim) is generally avoided as the safety and efficacy of such combinations have not been established.
Food Interactions
General Nutrition: There are no known specific food interactions (like grapefruit or dairy) that affect the absorption or metabolism of filgrastim.
Hydration: While not an interaction, maintaining high fluid intake is recommended to help the kidneys process the byproducts of increased cell production.
Herbal/Supplement Interactions
St. John's Wort: While primarily known for interacting with drugs metabolized by the liver, its effects on biologicals like filgrastim are not well-studied. It is best avoided to prevent unpredictable immune modulation.
Echinacea: Some herbalists suggest Echinacea stimulates the immune system. Because filgrastim is a potent immune stimulator, combining it with Echinacea could theoretically lead to an over-activation of the immune response.
Lab Test Interactions
Imaging (PET/CT Scans): Filgrastim increases metabolic activity in the bone marrow. On a PET scan, this can appear as 'hot spots' in the bones, which might be mistaken for the spread of cancer (metastasis).
Management: Patients should inform their radiologist if they have received filgrastim within the last 7-10 days.
Leukocyte Count: Filgrastim will obviously increase the white blood cell count on a CBC, which is the intended effect, but it must be interpreted in the context of the therapy timing.
> Important: Tell your doctor about ALL medications, including over-the-counter drugs, vitamins, and herbal products. Even 'natural' supplements can interfere with how your body responds to biological therapy.
Relative Contraindications
These are conditions where the healthcare provider must carefully weigh the risks against the benefits:
Sickle Cell Disorders: Filgrastim can cause 'sickle cell crisis' in patients with sickle cell anemia or sickle cell trait. These crises can be severe and sometimes fatal. If used, it must be done with extreme caution and intensive monitoring.
Myeloid Malignancies (Certain Types): Because filgrastim is a growth factor for myeloid cells, there is a theoretical concern that it could act as a growth factor for certain types of myeloid tumor cells (like certain leukemias). Its use in chronic myeloid leukemia (CML) or myelodysplastic syndrome (MDS) is usually avoided unless specifically indicated.
Pre-existing Splenomegaly: Patients with an already enlarged spleen are at a higher risk for splenic rupture.
Cross-Sensitivity
Pegfilgrastim: There is a high degree of cross-sensitivity between filgrastim and pegfilgrastim. If you are allergic to one, you are almost certainly allergic to the other.
Latex: The needle cap of some prefilled syringes may contain natural rubber latex. Patients with severe latex allergies should check the specific product packaging or use vials instead.
> Important: Your healthcare provider will evaluate your complete medical history, including any rare genetic blood disorders, before prescribing Filgrastim.
Filgrastim is frequently used in pediatric oncology and for children with severe chronic neutropenia.
Growth Monitoring: Long-term daily use in children requires monitoring of bone density and growth, although significant negative impacts on height or development have not been consistently reported.
Safety: The safety profile in children is generally comparable to that in adults, with bone pain being the most common complaint.
Geriatric Use
In clinical trials, no overall differences in safety or effectiveness were observed between subjects over 65 and younger subjects. However, elderly patients may be more prone to certain side effects like bone pain or may have underlying cardiac conditions that require closer monitoring during the fluid shifts associated with Capillary Leak Syndrome.
Renal Impairment
In patients with severe renal impairment, the half-life of filgrastim is prolonged and the maximum concentration (Cmax) is increased. However, clinical data suggest that the drug is still well-tolerated and standard doses are typically used. No specific GFR-based dose adjustments are mandated in the current FDA labeling.
Hepatic Impairment
No formal studies have been conducted in patients with hepatic impairment. Since the liver is not the primary route of elimination for this protein, hepatic impairment is not expected to significantly alter the pharmacokinetics of filgrastim.
> Important: Special populations, particularly pregnant women and those with sickle cell disease, require individualized medical assessment and a multidisciplinary care team.
| Bioavailability | ~60-70% (Subcutaneous) |
| Protein Binding | Negligible (acts as a free protein) |
| Half-life | 3.5 hours |
| Tmax | 2 to 8 hours (Subcutaneous) |
| Metabolism | Endogenous protein catabolism |
| Excretion | Renal and Neutrophil-mediated |
Chemical Information
Molecular Formula: C845H1339N223O243S9
Molecular Weight: Approximately 18,800 Daltons
Structure: A single-chain, 175-amino acid polypeptide. It differs from natural human G-CSF in that it is non-glycosylated and has an extra N-terminal methionine residue required for expression in E. coli.
Solubility: Soluble in water-based buffers at slightly acidic pH.
Drug Class
Filgrastim belongs to the therapeutic class of Hematopoietic Growth Factors. Related medications include:
Pegfilgrastim: A pegylated (long-acting) version of filgrastim.
Sargramostim: A GM-CSF that stimulates both neutrophils and macrophages.
Tbo-filgrastim: A slightly different biological variant used for similar indications.