Atgam contains equine anti-thymocyte globulin (eATG) 50 mg/mL, a polyclonal IgG immunoglobulin produced by hyperimmunisation of horses with human thymic lymphocytes and supplied as a concentrate for intravenous infusion. eATG binds multiple T-lymphocyte surface antigens (CD2, CD3, CD4, CD8, CD11a, CD18, CD25, CD44, CD45) producing rapid lymphocyte depletion through complement-dependent cytolysis, antibody-dependent cell-mediated cytotoxicity, and apoptosis, alongside modulation of activation, adhesion and trafficking of remaining T-cells. ATC class L04AA03 (selective immunosuppressants). Compared with rabbit ATG, equine ATG has different binding specificities and is the historical agent of choice for severe aplastic anaemia. It is administered exclusively as an inpatient intravenous infusion under specialist haematological/transplant supervision.
⚠️ Warnings
Administered only by haematology/transplant specialists in centres with full supportive care and resuscitation facilities. Mandatory intradermal skin test before first infusion (0.1 mL of a 1:1000 dilution); if positive, do not administer. Premedication with paracetamol, antihistamine and intravenous corticosteroid is standard. Slow infusion (at least 4-12 hours) to reduce cytokine release. Monitor full blood count, transaminases and renal function daily during therapy. Active prophylaxis against Pneumocystis jirovecii, CMV reactivation and viral hepatitis is recommended. Live vaccines are contraindicated during and for 6 months after therapy. Pregnancy: avoid unless benefit outweighs risk; effective contraception during and after therapy.
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