Immune Globulin (Human), Intravenous (IVIG)
**Immune Globulin (Human), Intravenous (IVIG)** is a highly concentrated biological product consisting of fractionated immunoglobulins (primarily IgG) pooled from thousands of human plasma donors. In veterinary medicine, it is primarily utilized as an expensive, off-label **salvage therapy** for severe, refractory immune-mediated diseases when conventional immunosuppressive therapies (like glucocorticoids or cyclosporine) have failed. **Key Clinical Applications:** * **Primary Immune-Mediated Thrombocytopenia (pIMT):** Shows the most promise in veterinary studies for rapid platelet recovery. * **Immune-Mediated Hemolytic Anemia (IMHA):** Used in refractory cases, though prospective studies show mixed results regarding survival benefits compared to standard therapy. * **Immune-Mediated Dermatopathies:** E.g., Erythema multiforme, Stevens-Johnson syndrome, and toxic epidermal necrolysis. > **Clinical Pearl:** Because IVIG is a human blood product, its use in veterinary medicine is controversial due to ethical considerations regarding human supply shortages, the extremely high cost of the drug, and the risk of hypersensitivity reactions to foreign proteins.
Mechanism: IVIG exerts complex immunomodulatory effects through multiple concurrent pathways rather than a single mechanism: * **Fc Receptor Blockade:** The massive influx of human IgG binds to and saturates **Fc receptors** on the patient's mononuclear phagocyte system (macrophages) → prevents the phagocytosis and destruction of the patient's own autoantibody-coated red blood cells or platelets. * **Anti-idiotypic Antibodies:** Contains antibodies that directly bind to and neutralize pathogenic autoantibodies. * **Cytokine Modulation:** Binds to and downregulates pathogenic cytokines including **Interleukin (IL)-1a**, **IL-6**, and **Tumor Necrosis Factor-alpha (TNF-α)**. * **Receptor Interference:** Binds to **CD5 receptors** and **T-cell receptors**, suppressing pathogenic T-cell and B-cell activation. * **Negative Feedback:** High circulating IgG levels provide negative feedback → downregulation of endogenous antibody production by B lymphocytes.
Dosing by species
- Immune-mediated diseases (IMHA, ITP) - General · 0.3-1.5 grams/kg · IV · varies · varies · Cost-benefit must be weighed carefully due to extreme expense.
- IMHA (refractory to conventional treatment) · 0.5-1.5 grams/kg · IV · once · over 12 hours
- Primary immune-mediated thrombocytopenia (pIMT) · 0.5 grams/kg · IV · single infusion
- Refractory erythema multiforme, Stevens-Johnson syndrome/toxic epidermal necrolysis, and other cutaneous adverse drug reactions · 0.5-1 gram/kg · IV · 1-2 times, 24 hours apart · over a 4-6 hour period; may need to be repeated for 3-4 days in a row · Uses a 5-6% solution.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Routes of administration
Contraindications
- Prior hypersensitivity reactions to human albumin or human blood products
Adverse effects
- Increased blood pressure
- Local injection site reactions (pain, tenderness)
- Anaphylaxis / Hypersensitivity reactions
- Volume overload (due to colloid-like properties)
- Thrombotic events
- Fever, chills, facial flushing, nausea (human data)
- Renal dysfunction / Acute renal failure (human data)
Drug interactions
- Live Vaccines · IVIG may interfere with the immune response and efficacy of the vaccine due to passively transferred antibodies.
Monitoring
- Vital signs (blood pressure, temperature, heart rate)
- Lung auscultation (to assess for pulmonary edema/volume overload)
- Renal function tests (BUN, Creatinine) and urine output
- Clinical efficacy (e.g., serial platelet counts, hematocrit, dermatological lesion resolution)
Overdose
Overdosage primarily increases the risk of **fluid volume overload** due to the colloid-like osmotic pull of the concentrated proteins. Other reactions could include severe pain and tenderness at the injection site, and potentially an increased risk of thrombotic events or renal impairment.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.