Intravenous immunoglobulin increases risk of thrombotic events
Scott Gottlieb New York
S G Baxter Healthcare Corporation and the American Red Cross have issued
joint warnings of a possible link between intravenous immunoglobulin and serious
thrombotic events that could lead to chest pain, congestive heart failure, and
myocardial infarctions in certain patients.
The two organisations have posted their warning on the website of the US Food
and Drug Administration (www.fda.gov/medwatch/SAFETY/2002/safety02.htm#igiv).
Baxter has also sent a warning letter to physicians.
Intravenous immunoglobulin consists of antibodies derived from pooled human
plasma, which are stabilised with sugars or proteins, such as glucose, sucrose,
or albumin. The product helps to fight infection in those with weakened immune
systems and is commonly used in patients with HIV, hepatitis C, a bone marrow
transplant, certain leukaemias, and neurological diseases such as Guillain-Barré
syndrome, multifocal motor neuropathy, chronic inflammatory demyelinating
polyneuropathy, and dermatomyositis.
Although the exact cause of the clot related problems is unknown, rapid
infusion of intravenous immunoglobulin is considered a "possible risk factor,"
according to Baxter (which makes one product, Gammagard S/D) and the Red Cross
(which distributes a second, Polygam S/D).
Statements advising caution in administering intravenous immunoglobulin to
patients with cardiovascular disease or previous clot related problems have been
added to the labelling of both products, and healthcare workers are being
advised to evaluate carefully patients with risk factors such as coronary artery
disease, hypertension, cerebrovascular disease, and diabetes.
It has long been known that treatment with intravenous immunoglobulin
increases the viscosity of serum, especially in patients with high normal serum
viscosity as a result of conditions such as cryoglobulinaemia,
hypercholesterolaemia, or hypergammaglobulinaemia.
In the new warning letter sent to physicians, Baxter noted 28 studies
published in the medical literature that describe the occurrence of thrombotic
events in patients receiving intravenous immunoglobulin.
"From both the medical literature and our internal pharmacovigilance/quality
assurance program, we continue to receive reports describing serious thrombotic
(vascular occlusive) events possibly associated with the infusion of immune
globulin intravenous," Baxter wrote in the letter.
"Our own recent analysis of serious adverse events reported via
pharmacovigilance, has identified rapid infusion of immune globulin intravenous
[IVIG] as a possible risk factor. For example, in one report researchers
identify 89 adverse events associated with 341 rapid infusions of IVIG in 50
patients, 3.5% of which were considered 'major.' This amounted to a 'major'
event in 11 out of 50 patients (22%)" (Neurology 2001;57:1699-701).
"It is these 'major' events, and their frequency, which is of concern to us,"
Baxter wrote, "as these events included chest pain, myocardial infarction,
congestive cardiac failure, severe headache requiring hospitalisation, pulmonary
embolism and transfusion related acute lung injury. These are serious events
almost certainly directly related to the rapid infusion protocol (reaching as
high as 800 ml/hour) in what is essentially an at-risk population."
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