Mechanism of action and pathogenesis
To understand how the drug works, it is necessary to review the pathogenesis of joint damage in rheumatoid arthritis. Proinflammatory cytokines, primarily TNF-α and IL-1, play a key role. They are secreted by synovial macrophages and trigger a cascade of destruction:
- Stimulate the production of collagenase (an enzyme that destroys joint tissues).
- Increase bone resorption.
- Inhibit the synthesis of cartilage proteoglycans.
Chemically, infliximab (Infliximab) is a chimeric (murine-human) IgG monoclonal antibody. The drug belongs to targeted biological therapy.
Mechanism of action: Infliximab binds directly to circulating TNF-α in the blood. Unlike etanercept (which acts as a soluble receptor, or "decoy receptor"), infliximab binds to the cytokine itself and physically prevents it from interacting with cellular receptors. This interrupts the immune mechanisms of chronic inflammation.
Indications for use
The drug is prescribed to suppress unwanted immune responses in severe autoimmune processes. The main clinical indications include:
- Rheumatoid arthritis (important condition: used only in combination with the baseline cytostatic drug methotrexate).
- Ankylosing spondylitis (Bechterew's disease).
- Psoriasis.
- Crohn's disease.
Side effects and risks
The blockade of a key proinflammatory cytokine leads to profound suppression of the immune response. This induces iatrogenic immunodeficiency, requiring strict patient monitoring by the physician.
- Infectious complications: Conditions are created for the development of opportunistic infections. Tuberculosis, severe systemic mycoses, and viral infections pose the greatest danger. Patients require continuous monitoring.
- Hematological disorders: Pancytopenia may develop—a combined decrease in the blood levels of neutrophils, leukocytes, and platelets.
- Local reactions: Inflammation may develop directly at the injection site.
Dosage forms and administration rules
The drug is available as a lyophilized powder in 0.1 g ampoules.
Unlike other biological agents (e.g., anakinra or etanercept, which are administered subcutaneously), infliximab requires intravenous access.
- Route of administration: Intravenous infusion.
- Dosage: For the treatment of rheumatoid arthritis, the dose is calculated individually — 0.003 g/kg of body weight.
- Infusion rate: Administration must be slow, at a rate of 2 mL per minute. The total infusion time is approximately 2 hours.
- Frequency: The procedure is performed once every 2 weeks.
Briefly: answers to topical questions
What are the absolute contraindications to the use of infliximab?
The provided materials do not list specific absolute contraindications for infliximab. It is indicated that age under 18 is a contraindication in the treatment of psoriatic arthritis.
What other drugs belong to the TNF-alpha inhibitor group?
In addition to infliximab, tumor necrosis factor-alpha (TNF-alpha) inhibitors include:
- Adalimumab — used for psoriatic arthritis.
- Golimumab — classified as a TNF-alpha inhibitor.
- Etanercept — a soluble TNF receptor (decoy protein).
- Certolizumab pegol — used for psoriatic arthritis.
The suffix -ximab in pharmacology breaks down as follows: "xi" stands for chimeric, and "mab" stands for Monoclonal AntiBody.
Class and exam questions
What is the difference between the mechanism of action of infliximab and etanercept?
Infliximab is a monoclonal antibody that binds the TNF-α cytokine itself. Etanercept is a genetically engineered soluble TNF-α receptor (decoy protein).
Can infliximab be prescribed as monotherapy for rheumatoid arthritis?
No, in rheumatoid arthritis, infliximab is used only in combination with methotrexate.
What is the most severe complication of infliximab therapy?
Profound suppression of the immune response (iatrogenic immunodeficiency), which sharply increases the risk of tuberculosis activation, severe mycoses, and other opportunistic infections.
How should the drug be properly administered?
Strictly intravenous infusion, very slowly (at a rate of 2 mL per minute, total time about 2 hours), once every 2 weeks.
What else to study on this topic
- Classification of disease-modifying antirheumatic drugs
- Tumor necrosis factor-alpha (TNF-α) and its role in the pathogenesis of inflammation
- Etanercept and anakinra: a comparative profile of biological agents
- Opportunistic infections during immunosuppressive therapy
- Methotrexate: mechanism of action and rationale for combination therapy
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