IVIg

IVIg
Name	Intravenous Immunoglobulin
Type	Blood product
Tradename	Privigen, Gammagard, others
Other names	IVIg, IGIV
Drug class	Immunomodulator
Legal status	Rx-only
Routes of administration	Intravenous, Subcutaneous
Bioavailability	100% (IV)
Protein bound	High
Metabolism	Catabolism
Elimination half-life	~3-4 weeks
Excretion	Reticuloendothelial system

IVIg. It is a therapeutic preparation of concentrated antibodies pooled from the plasma of thousands of healthy donors. Primarily used as an immunomodulator and for immunoglobulin replacement therapy, it is a critical treatment for a range of autoimmune, inflammatory, and immunodeficiency conditions. The complex mechanisms by which it exerts its effects involve modulation of the immune system through multiple pathways.

Medical uses

IVIg is approved by regulatory bodies like the U.S. Food and Drug Administration and the European Medicines Agency for several primary indications. Its cornerstone use is in primary immunodeficiency diseases, such as X-linked agammaglobulinemia and common variable immunodeficiency, where it provides passive immunity. In neurology, it is a first-line therapy for Guillain-Barré syndrome, chronic inflammatory demyelinating polyneuropathy, and multifocal motor neuropathy. It is also standard treatment for Kawasaki disease to prevent coronary artery aneurysms and for immune thrombocytopenic purpura to rapidly increase platelet counts. Off-label uses are extensive and include conditions like myasthenia gravis, dermatomyositis, and stiff-person syndrome, often when other immunosuppressive drugs like corticosteroids or rituximab are insufficient.

Mechanism of action

The mechanism is multifaceted and varies by disease, involving a combination of immunomodulatory effects. It provides neutralization of pathogens and autoantibodies via anti-idiotypic antibodies present in the pooled immunoglobulin G. It modulates Fc receptor expression and function on macrophages and other effector cells within the reticuloendothelial system, inhibiting phagocytosis of antibody-coated cells. IVIg contains natural anti-inflammatory cytokines and increases the expression of the inhibitory FcγRIIB receptor on B cells and dendritic cells. Furthermore, it influences complement activation and membrane attack complex formation, and can alter T cell and B cell activation and proliferation, contributing to its broad suppressive effect on aberrant immune responses.

Adverse effects

While generally safe, administration can be associated with several adverse reactions, often related to infusion rate. Common mild reactions include headache, chills, myalgia, fever, and flushing, which are typically manageable by slowing the infusion. More serious, though rarer, complications include aseptic meningitis, thromboembolic events such as stroke or myocardial infarction due to increased blood viscosity, and hemolytic anemia from anti-blood group antibodies. There is a risk of acute kidney injury, particularly with sucrose-stabilized products, and severe anaphylactic reactions can occur in patients with IgA deficiency who have anti-IgA antibodies. The risk of transmitting blood-borne pathogens like hepatitis C virus is now extremely low due to advanced viral inactivation steps during manufacturing.

Administration

IVIg is administered via slow intravenous infusion, typically in a hospital, clinic, or specialized home infusion setting under medical supervision. The dose is weight-based, often ranging from 0.4 to 1 gram per kilogram per cycle, with frequency varying from daily to monthly depending on the condition. Pre-medication with analgesics, antihistamines, or corticosteroids is common to prevent infusion-related reactions. For long-term replacement therapy, subcutaneous immunoglobulin administration is an alternative, allowing for slower, weekly infusions that can be self-administered, often resulting in more stable serum IgG levels and fewer systemic side effects.

History

The therapeutic use of immunoglobulin began in the 1930s with the work of Oswald Avery and colleagues on passive immunity. The first significant use of intramuscular immunoglobulin was for measles prophylaxis during an outbreak at a Pennsylvania boarding school. The development of large-scale Cohn fractionation by Edwin J. Cohn during World War II enabled the purification of plasma proteins, including gamma globulin. The transition to intravenous formulations in the 1980s, pioneered by companies like Baxter International and CSL Behring, was a major breakthrough, allowing for higher, more tolerable doses. This innovation expanded its use from replacement therapy to immunomodulation, revolutionizing treatment for autoimmune neuropathies and other conditions.

Society and culture

IVIg is a high-cost therapy, with annual treatments often exceeding tens of thousands of dollars, leading to significant budgetary impacts on healthcare systems like the National Health Service and insurers. Its production relies on a robust and volunteer-based plasma donation system, with major collection organizations including the American Red Cross and commercial entities like Grifols. Supply can be affected by plasma demand and manufacturing capacity, occasionally leading to shortages. Ethical discussions sometimes arise regarding its off-label use and cost-effectiveness. The therapy has been featured in medical dramas like *House* and has patient advocacy groups, such as the Immune Deficiency Foundation, dedicated to supporting individuals who rely on it.

Category:Immunologic factors Category:Blood products