By Leslie Vaughn, RPh
Immune Globulin (IG) is used to treat many conditions. Each brand of IG is approved by the U.S. Food and Drug Administration (FDA) for the treatment of specific conditions. In addition to the FDA-approved conditions, IG is used treat others illnesses that are not currently approved. For example, IG is FDA-approved for Primary Immunodeficiency Disease (PIDD), while it is not approved for treating dermatomyositis. However, the use of IG in the treatment of dermatomyositis has been studied and published in medical journals, making IG a proven treatment option for this condition.
Each brand of IG has its own labeled indications. This means the manufacturers conducted clinical trials to get FDA approval to market their brands as a treatment for a specific condition. All brands are FDA-approved for PIDD, and most are approved for the treatment of idiopathic thrombocytopenic purpura (ITP). Gamunex-C is the only brand approved for the treatment of chronic inflammatory demyelinating polyneuropathy (CIDP), and Gammagard Liquid is the only brand approved to treat multifocal motor neuropathy (MMN). People with these conditions can usually be treated with any brand ordered by their physician and approved by their insurance.
If someone has been prescribed a particular brand in the past and IG is to be resumed, it’s a good idea to use the same brand if there were manageable or no reactions. If new to therapy, brand selection is based on clinical criteria.
IG was originally introduced in the early 1950s for the treatment of PIDD. Since its introduction, there have been many changes to the manufacturing process. IG Products currently on the market are considered third- and fourth-generation products. And, because each product is manufactured using a slightly different process, there are small variations between them.
Key items a clinician considers when selecting a product for a patient are the person’s body style, their weight, conditions they have in addition to the one being treated with IG (such as diabetes, high blood pressure or other heart disease), whether they are pregnant or post-menopausal, other medications they take, how their kidneys are working, and whether they have a history of blood clots or migraines. Knowing this information is important when considering the differences between each of the products. It is also important for dosing recommendation and premedication selection, and it helps clinicians tailor patient-specific suggestions for tolerating therapy.
The key differences focused on in product selection are the concentration, IgA content, what is used to stabilize the product, osmolality and the route of administration. Details concerning each of these items will be reviewed in part 2 of this blog, so stay tuned!