Etanercept is a TNF decoy receptor, which binds to TNF and blunts the immune response.
Etanercept works as a fusion protein, which acts as a TNF decoy receptor. This drug mimics the inhibitory effects of naturally occuring TNF receptors, but has a longer half-life and more profound, long-lasting inhibitory effect.
This drug neutralizes the actions of TNF-α by working as an anti-TNF-α antibody. It binds with high affinity to TNF, blunting the inflammatory response by autoantibodies in various disorders.
Adalimumab is a monoclonal antibody and has a high specificity and affinity for TNF-α. It has the capability to lyse cells involved in the inflammatory process, helping to alleviate symptoms.
Infliximab is a monoclonal antibody and has a high specificity and affinity for TNF-α. It has the capability to lyse cells involved in the inflammatory process, helping to alleviate symptoms.
By blunting recruitment of other cytokines and lymphocytes, the immune response becomes halted and hindered. Preventing the activation of macrophages and inflammation leads to an increased risk of infection and patients should be considered immunocompromised.
Latent TB can become reactivated, as TNF-α inhibitors inhibit macrophages. Granulomas are effectively broken down with these medications, which release and disseminate TB which was encapsulated and isolated.
Prior to prescribing TNF-α inhibiting medications, physicians should order a PPD skin test in their patients to get a baseline level in patients. Patients with heavy inflammation or induration could be suspected to have TB and could end up with disseminated TB after treatment.
QFT is an interferon-γ release assay (IGRA) used in tuberculosis diagnosis. The QFT-GIT assay is an ELISA-based, whole-blood test that uses peptides from three TB antigens in an in-tube format. This test has a consistent specificity of >99% in low risk individuals and a sensitivity as high as 92% in individuals with active disease.
Patients should also have a chest x-ray to see if there is a history of latent TB infection, which could progress to disseminated TB with treatment of TNF-α inhibitors.
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