What is intravenous immunoglobulin?
Intravenous immunoglobulin (IVIG) is a blood product derived from the pooled plasma of about 10,000 to 20,000 individuals. It is highly purified from plasma by cold alcohol fractionation. Most of the immunoglobulins in IVIG are of the subtype IgG, but there are small and variable amounts of IgA.
What is it used for?
IVIG is used to prevent or reduce the severity of infections in persons with a weakened immune system. It provides the body with antibodies to protect against bacteria and viruses. In addition, IVIG can also neutralize autoantibodies (antibodies directed against one's self) and hence can be used to treat a variety of autoimmune disorders.
It is approved by the U.S. Food and Drug Administration (FDA) for the treatment of 7 conditions:
- Chronic Inflammatory Demyelinating Polyneuropathy (CIDP)
- Immune Thrombocytopaenic Purpura (ITP)
- Primary immunodeficiency states
- Secondary immunodeficiency in Chronic Lymphocytic Leukaemia
- Paediatric human immunodeficiency virus (HIV) infection
- Kawasaki syndrome
- Prevention of Graft vs. Host disease in adult bone marrow transplant recipient
The first four conditions account for 70% of IVIG use.1
However, given the broad action of IVIG, it can also be used to treat a variety of other conditions. The majority of the conditions listed in the table below have documented the efficacy of IVIG in small numbers of patients in uncontrolled studies.
|Primary immunodeficiency states||Secondary Immunodeficiency states|
|Haematologic disorders||Renal and vasculitic disorders|
|Neuromuscular disorders||Sensitization to HLA antigens prior to transplantation|
|Respiratory disorders||Skin diseases|
The use of IVIG in these and other conditions requires further assessment using randomised double-blind placebo-controlled trials.
IVIG for skin diseases
Dermatological conditions account for a small proportion of the total use of IVIG but it is a rapidly growing indication for its use. Although IVIG has been used to treat a number of dermatological diseases it must be noted that its effectiveness has only been shown through the treatment of small and mostly uncontrolled study groups. The exception is the use of IVIG in treating dermatomyositis, where a number or clinical studies, including a randomised double-blind placebo-controlled trial, have been performed.
The use of IVIG in these and other skin conditions requires further assessment using randomised double-blind placebo-controlled trials.
IVIG in Dermatomyositis
The mainstay of dermatomyositis treatment usually involves oral corticosteroids alone or in combination with an immunosuppressive agent such as methotrexate, azathioprine, cyclophosphamide and ciclosporin. These medicines all have significant side effects and often a less than adequate response is achieved with this conventional therapy.
IVIG is an effective additional therapy for patients with dermatomyositis who fail to respond to conventional therapy or who experience unacceptable side effects. A dose of 1-2 g/kg per month administered over 2 days or 5 days of each month is recommended (currently there is no clear difference in efficacy between the 2-day and 5-day regimen). A summary of clinical trials shows an overall response rate of 80% at about 2 months, with maximal response at 4 months. Most patients require ongoing IVIG therapy in conjunction with conventional treatments given at lower and better-tolerated dosages.
With the treatment of other skin conditions, IVIG should also be used as an additional therapy. A review of all reported cases of IVIG use in dermatological diseases showed efficacy to be much greater when IVIG is used as additional therapy, with a response rate of 88% compared with 46% if used alone.3
How is it given?
IVIG is given as an infusion into a vein over a period of time, usually from 2 to 24 hours. The frequency that it is given depends on the underlying condition and varies from once a day to once every 3 to 4 weeks.
How long do the effects of IVIG last?
The duration of the response from IVIG depends on the individual's metabolism and the disease state. On average, the effects of IVIG can last up to a month after each administration.
Risk of infection from IVIG
The pool of donors is carefully screened to eliminate anyone with abnormal liver function or exposure to viral hepatitis or HIV infection. The process of obtaining IVIG in itself removes viruses and bacteria from the plasma. Therefore, IVIG should not pose any risk of hepatitis C, hepatitis B or HIV transmission. Since the introduction of newer techniques of obtaining IVIG in 1987, there have been no cases of transmission of these viruses.
What are the precautions when taking this medicine?
Although immunoglobulins are antibodies from human plasma, individuals with certain conditions need to use this medication with caution. The following medical conditions warrant discussion with your doctor:
- Previous blood clots
- Kidney disease
- Heart disease
- Pregnant or contemplating pregnancy
Who should not take this medication?
IVIG should be avoided by:
- Individuals who have an allergy to immunoglobulins or any other part of this medicine
- Individuals who have IgA deficiency – Deficiency of IgA occurs in about 1 in 700 of the population and should be screened before IVIG therapy is instituted.
Side effects from IVIG therapy are generally mild and self-limiting. The most common side effects occur 30-60 minutes after onset of the infusion and include:
- Nausea or vomiting
- Lower back pain
- Tachycardia (rapid heart beat)
- Changes in blood pressure
- Myalgia (muscle pain)
These symptoms can be managed by stopping the infusion or a patient can be premedicated with antihistamines and intravenous hydrocortisone.
Other rare side effects include:
- Acute renal failure
- Blood clots
- Haemolysis (destruction of red blood cells)
- Neutropaenia (low white cell count)
What are the adverse reactions on the skin?
Skin reactions to IVIG are uncommon, and the exact incidence is unknown. Of all the reported rashes, a a blistering type of eczema is the most common (a type of dermatitis).2 It often begins at about 8 to 10 days after exposure to IVIG. The rash characteristically begins as a dyshidrotic eczema (pompholyx) i.e., small itchy blisters on the palms, but this may be followed by a more generalised eczematous eruption that spreads throughout the body. The affected individual may become erythrodermic (red all over) and pruritic (itchy).
Other skin reactions include:
- Maculopapular rash (typical drug eruption with flat and bumpy red spots resembling measles)
- Lichenoid eruption (like lichen planus)
- Diffuse hair loss
- Cutaneous vasculitis
What causes the skin reaction to IVIG?
The exact cause is unknown. It is thought that the body's immune system reacts to one or several substances within IVIG. This could be a stabilizing agent or a part of the immunoglobulin. T-cells (lymphocytes) are thought to play a part. The reaction may differ depending on the batch and type of IVIG as the immunoglobulin is obtained from a different pool of individuals.
What happens upon re-exposure to IVIG?
When an individual develops a skin reaction to IVIG, a second exposure may cause the rash to appear earlier (generally around 8-10 days after infusion) and become more extensive. This is because the immune system has developed memory T-cells and subsequent responses are faster and more severe. Switching the type of IVIG may cause a less severe reaction.