Leukopoiesis-stimulating agents

Why are leukopoiesis stimulants needed?

In clinical practice, physicians frequently encounter conditions in which bone marrow hematopoiesis is suppressed. A drop in the leukocyte count below 4,000 per 1 µL is called leukopenia. A more severe condition characterized by a sharp drop in granulocyte counts against the background of a general decrease in the white blood cell pool is termed agranulocytosis.

Under such conditions, the patient's body loses its natural resistance to infectious agents. The main etiological factors of hematopoiesis suppression include:

• Exposure to ionizing radiation (including during X-ray and radiotherapy).
• Exposure to toxic substances.
• Side effects of medications (especially antitumor drugs and antiviral medications in the treatment of HIV infection).

To prevent severe infectious complications, there is an urgent need for the pharmacological stimulation of leukopoiesis.

Colony-stimulating factors (CSFs)

The most effective modern stimulants are drugs based on recombinant human growth factors. Depending on the specific target cells they affect, four main groups are distinguished:

1. Granulocytic (G-CSF): selectively stimulate neutrophil production. A prominent representative is filgrastim. It regulates neutrophil production, accelerates their release into the bloodstream, and functionally activates these cells (enhances phagocytosis and chemotaxis). A noticeable increase in neutrophil counts is observed within the first 24 hours.
2. Macrophage (M-CSF): stimulate the production of monocytes (precursors of tissue macrophages).
3. Granulocyte-macrophage (GM-CSF): have a broad spectrum of action. They stimulate the proliferation of hematopoietic progenitor cells, increasing the formation of neutrophils, eosinophils, basophils, and monocytes. The main drugs are molgramostim and sargramostim. Molgramostim also acts as a cofactor for erythropoietin, additionally stimulating erythropoiesis.
4. Interleukin-3 (IL-3): a universal (multipotential) growth factor.

CSF preparations are prescribed for leukopenia following chemotherapy, bone marrow transplantation, myelodysplastic syndrome, and aplastic anemia. They are administered parenterally. With subcutaneous administration, peak concentration is reached in 3–4 hours.

Pyrimidine derivatives and other drugs

For milder forms of leukopenia, oral administration of drugs is appropriate. The main representatives of this group are methyluracil (hydroxymethyluracil) and pentoxyl.

Their pharmacodynamic effects are not limited solely to hematopoiesis:

• Moderate stimulation of leukopoiesis.
• Pronounced anti-inflammatory effect.
• Acceleration of cellular regeneration processes (drugs actively promote wound healing).

Comparative characteristics: pentoxyl has an irritating effect on mucous membranes, which is why it often causes dyspeptic disorders. Methyluracil lacks this drawback and is tolerated significantly better. Other drugs that stimulate leukopoiesis also include leucogen, batylol, and etaden (hydroxyethylaminoadenine).

Safety profile and adverse effects

Powerful pharmacological stimulation of the bone marrow by growth factors is naturally accompanied by a number of specific adverse reactions:

• Flu-like syndrome: fever, chills, muscle pain (myalgia), and characteristic bone pain (ossalgia). Bone pain is a direct consequence of active bone marrow stimulation.
• Gastrointestinal disturbances: dyspepsia (nausea, vomiting, diarrhea), loss of appetite (anorexia).
• Neurological symptoms: headache, dizziness, pronounced weakness (asthenia).
• Respiratory and allergic reactions: dyspnea, skin rash, pruritus.
• Specific effects of filgrastim: dysuria and transient arterial hypotension.
• Local reactions: soreness at the injection site.

Class and exam questions

What else to study on this topic

• Mechanisms of agranulocytosis development during cytostatic therapy.
• The role of macrophage colony-stimulating factor (M-CSF) in the immune response.
• The use of leukopoiesis stimulants in myelodysplastic syndrome and aplastic anemia.
• The effect of molgramostim on erythropoiesis (cofactor action with erythropoietin).
• Features of using leukopoiesis stimulants in patients with HIV infection.

Other topics in the section "Hematopoietic Agents"

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.