Leucogen

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Medically reviewed

Laura Arias

Last updated on 22/12/2025

This page provides general, reference-level information compiled from official medical sources. It is not a substitute for professional medical advice, diagnosis, or treatment. For decisions about your health, please consult a qualified healthcare professional.

Overview of Leucogen

Property Description
Active Ingredient Filgrastim (Recombinant Methionyl Human G-CSF)
Form Sterile, aqueous solution for injection
Pharmacological Class Hematopoietic Growth Factor
Common Use Management of low neutrophil counts (Neutropenia)
Origin Synthetic recombinant protein (Biologic)

What Type of Medicine is Leucogen?

Leucogen is a biologic drug whose active ingredient is Filgrastim, classified as a Hematopoietic Growth Factor and a Granulocyte Colony-Stimulating Factor (G-CSF) analogue. This medicine is a synthetic recombinant human protein created using recombinant DNA technology. It is structurally engineered to be a biosimilar—a close functional copy—of the naturally occurring G-CSF molecule in the human body. As a key member of the cytokine family, its function is highly specialized: to send signals that regulate the production of blood cells. This classification confirms that the medicine works by influencing the body’s natural cell-signaling pathways, a mechanism clinically recognized for its targeted efficacy in hematology.


Composition and Form: What is Filgrastim Made Of?

Leucogen is a single-active-ingredient product supplied as a sterile, aqueous solution for injection. As a therapeutic protein, the medicine is administered by the parenteral route, meaning it is delivered directly into the body, typically via a subcutaneous injection using a single-use pre-filled syringe or a vial. The solution consists of the active protein Filgrastim suspended in a base of Water for Injection alongside necessary excipients, which include stabilizing agents like acetate and Polysorbate 80. The specific composition ensures the stability and bioactivity of this complex protein molecule, a crucial requirement for all injectable biologics. This means the drug is formulated precisely to maintain its effectiveness when introduced into the body, a distinctive characteristic of its parenteral preparation.


General Purpose: Why is Leucogen Used?

The general purpose of Leucogen is to provide hematopoiesis support by stimulating the bone marrow to increase the production of specific immune cells. Its action centers on boosting the count of neutrophils, the body's primary white blood cells responsible for fighting bacterial infections. This targeted intervention is broadly designed to manage situations involving dangerously low neutrophil levels, such as during specific chemotherapy protocols that temporarily suppress bone marrow activity. This mechanism provides essential immune support to help restore the critical defenses of the patient.

Regulatory References

  1. Filgrastim Hexal EPAR (EMA)

What side effects are possible with Leucogen?

Possible Side Effects and Safety Information

Leucogen (Filgrastim) carries an officially documented safety profile based on structured regulatory classification systems, such as those used by the European Medicines Agency (EMA) and the U.S. Food and Drug Administration (FDA). This profile classifies possible adverse reactions by frequency and by affected body system.

Frequency-Classified Adverse Reactions

The most frequently reported effects are classified as Very Common (occurring in 1 or more in 10 patients). These typically include bone pain (musculoskeletal pain), headache, and pyrexia (fever). Reactions designated as Common (occurring in 1 or more in 100 patients) include thrombocytopenia (decreased platelets), leukocytosis (increased white blood cells), and splenomegaly (enlarged spleen, often asymptomatic).

Serious Adverse Reactions and Specific Safety Notes

Regulatory documents list serious adverse reactions that are classified as Uncommon (occurring in 1 or more in 1,000 patients). These include Splenic Rupture, Capillary Leak Syndrome (CLS), and inflammation of the kidney (Glomerulonephritis). Serious hypersensitivity reactions are also documented.

Population-Specific Constraints exist in the official labeling. For individuals with Sickle Cell Disease or trait, the risk of a severe and sometimes fatal Sickle Cell Crisis is noted as a specific safety concern. Furthermore, in patients with Severe Chronic Neutropenia (SCN), there is an established association between long-term use and the development of Myelodysplastic Syndrome (MDS) or Acute Myeloid Leukemia (AML). The product is also formally Contraindicated in those with known severe hypersensitivity to Filgrastim or its excipients.

Overdose and Emergency Response

The official regulatory profile for Leucogen (Filgrastim) addresses overdose by documenting the drug's exaggerated pharmacological effect on the hematopoietic system.

Overdose Manifestations and Required Action

The chief manifestation of overdose documented in official prescribing information is Excessive Leukocytosis, defined as White Blood Cell (WBC) counts of 100 imes 10^9/ L or greater. This finding represents the maximum expression of the drug's intended action and is a dose-dependent physiological outcome. To mitigate the potential risks associated with this condition, regulatory authorities mandate the immediate discontinuation of Filgrastim therapy.

When to Seek Urgent Medical Help

Urgent medical help must be sought for a suspected overdose. Patients are instructed to contact a regional poison control centre for specific management guidance as written in official documents. The mandatory action for avoiding risks is stopping the medicine when the Absolute Neutrophil Count (ANC) surpasses 10 imes 10^9/ L after the nadir has occurred.

Management and Monitoring Requirements

The regulatory profile confirms that no specific pharmacological antidote is known for Filgrastim overdose. Management relies on symptomatic and supportive treatment and continuous monitoring of Complete Blood Counts (CBCs). The effects of the exaggerated dose generally reverse, with neutrophil and WBC counts typically returning to pretreatment levels within one to seven days following the mandated discontinuation of the medicine.

Therapeutic Uses of Leucogen

The core therapeutic use of Leucogen (Filgrastim) is to provide essential supportive relief for the immune system by addressing the deficiency of infection-fighting white blood cells. Its application is relevant across conditions where neutrophil counts are severely low (neutropenia), to support the patient during situations where risks are present. The use is relevant across several domains of patient care where temporary or sustained immune compromise occurs.

Main Uses and Therapeutic Benefits

Leucogen is commonly applied in clinical settings that involve acute or disruptive symptom patterns following medical intervention, such as myelosuppressive chemotherapy. It is also relevant for the chronic management of conditions like congenital, cyclic, or idiopathic neutropenia, and is relevant in contexts involving procedures like hematopoietic progenitor cell collection for transplantation procedures. The medication helps address symptom clusters that may become intense or disruptive, particularly those related to a high vulnerability to serious bacterial infections and febrile episodes.

“The therapy is aligned with domains involving significant symptom expression, contributing to improved comfort during periods of heightened symptoms.”

This supportive treatment may assist with maintaining functional stability and contributes to easing the overall symptom load during periods of heightened distress.

Quick Fact: Symptomatic Support for Vulnerability
This medicine is commonly used to help manage the risk of febrile neutropenia, a high-risk syndrome of fever with profound immune compromise, and may be part of symptomatic management during acute episodes.

Eligibility and Restrictions for Use

Leucogen (Filgrastim) is subject to specific regulatory eligibility rules that define its use. The medicine is absolutely contraindicated in patients with a history of serious allergic reactions or hypersensitivity to human G-CSFs (Granulocyte Colony-Stimulating Factors) or to E. coli-derived proteins.

A strict time-based prohibition applies: the medicine must not be administered within the 24-hour period prior to or after the administration of cytotoxic chemotherapy. Furthermore, use is conditional in patients with sickle cell disorders due to the documented risk of severe crisis, and in patients with suspected Myelodysplastic Syndrome (MDS) who are not receiving chemotherapy.

Eligibility is established for children with Severe Chronic Neutropenia and for adults, and it is not restricted by severe renal or hepatic impairment. However, specific dosage recommendations are limited for older adults due to insufficient data. For pregnancy, use is permitted only if the potential benefit justifies the potential risk to the fetus, and use during lactation is cautionary, as it is not known if the medicine is excreted in human milk.

What should I know about interactions with other medicines?

Interactions with other medicines and products

The official regulatory profile for Leucogen (Filgrastim) primarily defines interaction requirements related to administration timing and pharmacodynamic effects, rather than common metabolic or chemical interactions.

Interaction Type Interacting Substance/Procedure Regulatory Constraint
Timing-Mandated Restriction Cytotoxic Chemotherapy / Radiotherapy / Stem Cell Transplant Must not be administered within the 24-hour period before or after the procedure.
Pharmacodynamic Potentiation Lithium Use with caution due to documented additive effect on neutrophil release.

Timing and Procedural Restrictions Leucogen administration is subject to specific timing separation rules mandated by regulatory bodies when used alongside certain anti-cancer treatments. Official labeling strictly prohibits the administration of Filgrastim within a 24-hour period extending both before and after receiving cytotoxic chemotherapy, radiotherapy, or undergoing a bone marrow or stem cell transplant procedure. This formal timing constraint must be observed.

Pharmacodynamic Interactions A documented additive pharmacodynamic interaction exists with certain medicinal products, including Lithium. Because Lithium may also potentiate the release of neutrophils, its co-administration is officially designated as requiring caution.

Metabolic and Food Profile The regulatory documents confirm there are no known interactions with common foods or drinks. Furthermore, no interactions mediated by the Cytochrome P450 enzyme system or major drug transporters are documented in the official regulatory profile for Filgrastim.

Mechanism of Action

The action of Leucogen (Filgrastim) is a highly specialized biological process focused on activating and regulating the body's cell production machinery.

Targeted Receptor Agonism and Granulopoiesis

The drug's molecular interaction is defined by Filgrastim's specific agonism for the G-CSF Receptor found on bone marrow progenitor cells. By binding to this target, it activates key intracellular pathways, including JAK/STAT, to robustly stimulate the proliferation and maturation of neutrophil precursor cells (granulopoiesis).

Systemic Mobilization and Functional Priming

The accelerated production process results in the increased mobilization and release of mature neutrophils from the bone marrow into the circulation. This mechanism rapidly increases the Absolute Neutrophil Count (ANC) and functionally primes the circulating cells, resulting in enhanced phagocytic capacity and cytotoxicity.

Biological Limits to Action

The drug's mechanism is fundamentally constrained by the availability of viable progenitor cells in the bone marrow, as the proliferative effect requires the presence of the target cell population. Furthermore, the rising count of neutrophils contributes to the drug’s non-linear clearance through receptor internalization and degradation, biologically contributing to its half-life and clearance rate.

Dosage and Administration Information

How to Use Leucogen: Official Administration Guidelines

Leucogen is a veterinary medicinal product that must be administered only by the subcutaneous route, meaning the injection is given just under the skin. The official instructions for its preparation and schedule must be strictly followed to ensure correct use.


Official Dosing and Preparation

Administration Component Official Instruction
Dose One milliliter (1 ml) per injection.
Preparation The vial must be shaken gently before use to ensure the suspension is properly mixed.
Timing (General) The product must be used immediately once the vial has been opened.

Primary and Booster Schedules

The administration schedule is structured into a primary course followed by regular maintenance boosters.

  • Primary Vaccination Course: The first injection is given to kittens from eight weeks of age. This is followed by a second injection administered 3 to 4 weeks later.
  • Booster Vaccination (Revaccination): A single 1 ml dose must be administered annually after the completion of the primary course to maintain the required protective effect.

Recent Clinical Evidence

Research Evidence / Overview of Studies for Leucogen

This section describes the types of clinical studies that have been conducted for Leucogen (filgrastim) and what these research efforts have explored. Findings describe group patterns, not personal outcomes and do not offer clinical advice.


Evidence from Studies in Chemotherapy-Induced Neutropenia (CIN)

The research for this indication primarily involved Randomized Controlled Trials (RCTs) that compared outcomes in patients receiving chemotherapy who were given Filgrastim versus those given a placebo or no treatment. Research examined the duration of Severe Neutropenia and the incidence of Febrile Neutropenia (FN). The findings describe patterns observed in the studies where the groups receiving Filgrastim reported shorter measured durations of severe neutropenia and lower frequencies of reported episodes of Febrile Neutropenia. Long-term survival data show patterns that were not consistently reported or were similar across groups in some analyses.


Evidence in Acute Myeloid Leukemia (AML) and Bone Marrow Transplantation (BMT)

For patients with Acute Myeloid Leukemia (AML), large, controlled trials monitored the time to neutrophil recovery, days with fever, and hospitalization. Studies report how symptoms evolved in the observed populations, describing faster measured recovery times for Absolute Neutrophil Counts in the groups receiving Filgrastim compared to control groups. Long-term follow-up protocols were studied for patterns related to overall survival and remission duration, and no negative association was observed. For Bone Marrow Transplantation (BMT), research examined the time to engraftment, and reports described differences in the measured time to engraftment compared to control groups.


Evidence in Severe Chronic Neutropenia (SCN)

Leucogen was evaluated in studies examining conditions characterized by fluctuating or episodic manifestations related to Severe Chronic Neutropenia (SCN). Research involved both Controlled Phase III Trials and extensive long-term observational registries. Research highlights changes measured during the study period, describing that the groups receiving chronic administration generally had higher measured neutrophil counts, and that patterns were observed related to a lower incidence and duration of infection-related events in the study populations.


What the Research Shows is Still Uncertain

While a large body of evidence exists, the research landscape still contains areas where certainty remains low or where more research is needed: Long-term effects are not fully established for all populations, and subgroup findings are uncertain in cases where the initial clinical trials did not include enough patients with specific comorbidities. The research does not determine whether an individual will respond similarly to the group patterns described in the studies.

Frequently Asked Questions (FAQ)

Common questions about Leucogen (FAQ)

Q: How does Leucogen specifically help with low white blood cell counts?

A: Leucogen's active component, Filgrastim, is a type of protein that acts as a signal in the body. It works by binding to the G-CSF receptor on cells in the bone marrow. This binding stimulates the growth and maturation of these cells, resulting in an increase in the body’s circulating neutrophil count (a type of white blood cell).


Q: What is the expected time frame to see effects from Leucogen?

A: Official information indicates that a measurable rise in circulating neutrophil counts is typically seen within 1 to 2 days after starting treatment. After the medicine is stopped, neutrophil counts usually decline back to pre-treatment levels within one to seven days.


Q: Can Leucogen be taken with common pain relievers?

A: Official regulatory documents specifically detail known interactions with certain medications, such as Lithium, and administration timing around chemotherapy. Information regarding common, over-the-counter pain relievers is not explicitly detailed in the same way. The regulatory profile generally advises reporting all medications and supplements to a healthcare provider.


Q: Does Leucogen affect platelet (PLT) count as well as white blood cell (WBC) count?

A: Yes, official safety documents indicate that while the medicine primarily increases white blood cell counts, thrombocytopenia (a decrease in platelet count) is also listed as a common adverse reaction in the safety profile for some patient groups. Leukocytosis (increased white blood cells) is also common.


Q: Does Leucogen have a low-cost or oral administration advantage compared to other similar medicines?

A: Regulatory documents confirm that this medicine is formulated as a sterile solution for injection. It must be given by injection under the skin (subcutaneous) or into a vein (intravenous), and administration by mouth is not an approved method of use.


Q: How is Leucogen clearance described in official information?

A: The medicine is eliminated from the body through a non-linear clearance process. This means the rate of elimination changes depending on the dose and the number of target cells present. Official documents state that the clearance process is partly influenced by the target cells themselves (receptor-mediated disposition).


Q: Is Leucogen the same as or similar to Filgrastim or Pegfilgrastim?

A: Leucogen is a specific brand name for the active ingredient Filgrastim. Pegfilgrastim is a different, modified version of the same basic molecule that has been engineered to last longer in the body. All are classified as Granulocyte Colony-Stimulating Factor (G-CSF) analogues used to raise white blood cell counts.


Q: Does Leucogen start working right away?

A: Its biological action starts by binding to the cell receptors shortly after administration to activate cell signals in the bone marrow. However, the measurable, clinical effect—the increase in circulating neutrophil counts—typically takes 1 to 2 days to become noticeable in blood tests.


Q: Can Leucogen be taken by mouth, or is it always an injection?

A: Leucogen is a protein-based medicine that is administered only as an injection, either subcutaneously (under the skin) or intravenously (into the vein). It is not approved for administration by mouth because its active ingredient would be broken down by the digestive system.


Q: Are there any serious, but rare, side effects associated with Leucogen use?

A: Yes, official safety documents list several serious but uncommon reactions. These include Splenic Rupture, Capillary Leak Syndrome (CLS), Glomerulonephritis (kidney inflammation), and Aortitis (inflammation of the aorta). These are rare events but are documented in regulatory profiles.


Q: Does Leucogen cause fatigue or dizziness?

A: Official safety documents list fatigue (tiredness) as an event that has been reported. Dizziness has also been reported, sometimes in connection with other adverse events. If any side effects are experienced, official guidance indicates they should be discussed with a healthcare provider.


Q: Can Leucogen affect liver function or blood counts other than white blood cells?

A: Official labeling notes that the medicine can affect other blood counts, specifically listing thrombocytopenia (decreased platelets) as a common reaction. Additionally, non-clinical data indicate that temporary increases in measures of liver and bone activity were observed in studies.


Q: Is it normal to feel flu-like symptoms after taking Leucogen?

A: The official side effect profile lists common reactions such as pyrexia (fever) and headache. Since other reactions like fatigue and nausea have also been reported, these documented reactions can result in symptoms that a patient might describe as flu-like.


Q: Are there any specific food or drinks that should be avoided while using Leucogen?

A: Official regulatory documents state that there are no known interactions with common foods or drinks. The medicine’s effect is generally not influenced by typical dietary intake.


Q: Are long-term studies available on the effects of Leucogen?

A: Yes, the safety and patterns of use for the medicine in certain ongoing conditions, like Severe Chronic Neutropenia (SCN), have been evaluated in long-term observational registries and studies to evaluate the safety and patterns of use over an extended period.


Q: What is the average duration of treatment with Leucogen?

A: The length of treatment varies based on the medical condition being addressed, but for chemotherapy-induced neutropenia, official documents indicate administration typically lasts up to two weeks, or until the neutrophil count has recovered to a certain level.


Q: Can Leucogen be used for patients who have been exposed to radiation?

A: Yes, regulatory bodies have approved Filgrastim for use in patients acutely exposed to myelosuppressive doses of radiation. The use in this context is intended to stimulate the bone marrow to increase the production of white blood cells.


Q: Does Leucogen carry a warning about latex sensitivity?

A: Yes, official labeling for some formulations indicates that the needle cover of the pre-filled syringe is made of dry natural rubber (latex). This information is included as a warning for individuals with a known sensitivity or allergy to latex.


Q: Are there specific symptoms that require immediate medical attention while on Leucogen?

A: Yes, symptoms associated with serious events are listed as requiring immediate medical evaluation. These include pain in the left upper stomach or shoulder (Splenic Rupture), sudden trouble breathing or fever (Acute Respiratory Distress Syndrome), and unexplained fever, pain in the stomach or back, or fatigue (Aortitis).


Q: How does Leucogen affect the risk of infection?

A: The medicine is designed to increase the number of neutrophils, which are the body’s primary immune cells for fighting bacterial infections. Studies have examined its use to address infection risk, and research in certain study populations reports a lower incidence and shorter duration of infection-related events.


Q: Is Leucogen used to help mobilize blood cells before a procedure?

A: Yes, one approved indication for the medicine is for the mobilization of autologous peripheral blood progenitor cells (PBPC). This process helps move blood stem cells from the bone marrow into the circulating blood so they can be collected for a later transplant procedure.


Q: Can Leucogen cause changes in mood or sleep?

A: Official regulatory documents do not list specific mood changes or sleep disorders as common adverse events. However, general adverse reactions such as headache and fatigue are noted, which can sometimes affect a patient’s overall well-being.


Q: What is the meaning of 'myelosuppressive chemotherapy' in relation to Leucogen?

A: Myelosuppressive chemotherapy refers to cancer treatments that suppress or inhibit the bone marrow’s ability to produce new blood cells. The main purpose of Leucogen is to counteract this temporary suppression by stimulating the bone marrow to produce white blood cells.


Q: Has Leucogen been studied in patients with congenital neutropenia?

A: Yes, Filgrastim is approved for patients with Severe Chronic Neutropenia (SCN), and this category includes clinical studies that specifically involved patients with congenital neutropenia, which is a genetic form of the condition.


Q: Does Leucogen have a known risk of inflammation of the aorta (aortitis)?

A: Yes, an inflammatory condition of the large artery known as the aorta (aortitis) has been reported in patients receiving the medicine. Regulatory bodies have included this risk in the official post-marketing safety warnings.


Q: Are there different formulations or brand names of the drug Leucogen?

A: Yes, the active ingredient Filgrastim is marketed under different brand names, including Leucogen. Furthermore, the medicine is also available as several biosimilar products, which are versions approved to be highly similar to the original reference product.


Q: Does Leucogen influence signaling pathways in cancer cells?

A: Regulatory warnings emphasize that the medicine is a growth factor that primarily stimulates neutrophil production. Official safety documentation notes that the possibility that it can act as a growth factor for certain tumor types cannot be ruled out, and caution is advised in patients with certain malignancies.

How should Leucogen be stored and disposed of?

How to Store and Dispose of Leucogen

Official regulatory documents require Leucogen (Filgrastim) to be stored under controlled conditions to protect the stability of this injectable biologic.


Storage Requirements

  • Temperature: Store refrigerated at 2 C to 8 C (36 F to 46 F). Do not freeze, and do not shake the container.
  • Protection: Keep the medicine in its original carton to protect it from light.
  • Stability: If removed from refrigeration, it may be kept at room temperature (up to 30 C) for a single period of no more than 24 hours.
  • Safety: The product must be kept out of the sight and reach of children.

Disposal Instructions

Used needles and syringes must be immediately placed in an FDA-cleared sharps disposal container.

Unused or expired Leucogen must not be disposed of in household trash or poured down the sink or toilet (wastewater). Disposal must adhere to local requirements for medical waste.

Attention! Always consult to a doctor or pharmacist before using pills or medicines.

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