Many symptom complexes are treated with IVIG and SCIG in LC19 without robust evidence. Just because they are natural, they still incur a heavy burden in their use. Their production has serious limitations which can involve the success of the treatment similar to the use of other blood products.
This post is a cut and paste of a comment I placed in another sub with a few modifications. The two invasive therapies are becoming more popular in their use despite being inappropriate in many presentations. The experiences from their applications will inevitably produce more selective guardrails on when and where they are clearly indicated.
This post does not give any direction on the latter point. That decision is decided between patient and physician. The heavy costs of therapy are not fully covered by insurance in many situations. Each use of biologics causes serious reactions to the native immune system. Premedication helps to moderate reactions. Still the benefits must outweigh the risks especially when there are serious health consequences in their use.
...............................................................
https://ameripharmaspecialty.com/ivig/are-ivig-products-interchangeable/
"Why Are IVIG Products Not Interchangeable?
There are several key factors that make IVIG products non-interchangeable.
Composition The composition of IVIG products typically varies among the IVIG brands. Each IVIG product can have a specific immunoglobulin (antibody) type and concentration. For example, our body typically has five types of immunoglobulins: IgG, IgA, IgE, IgM, and IgD.
Among the immunoglobulins, IgG is the most abundant antibody in the human plasma and is a principal component of all IVIG products (present in 95% of the concentration).
Other antibodies, such as IgA and IgM, are present in trace amounts in IVIG products.
The primary antibody (IgG) also has four sub-types (IgG1, IgG2, IgG3, and IgG4), and it is possible that different IVIG products may contain varying proportions of IgG subclasses, IgA and IgM. This may also make IVIG products different in terms of their antigen specificity.
For example, if a patient has IgA antibodies, IVIG products with a low proportion of IgA, like Flebogamma or Gammagard S/D, may be prescribed. However, if a patient with IgA antibodies also has diabetes, then the IVIG product Gammagard S/D could be potentially life-threatening to diabetic patients as it contains glucose as a stabilizing agent.
Purification Process Pharmaceutical companies may use slightly different purification methods (such as fractionation, precipitation, and chromatography) to purify the immunoglobulins from human plasma. Variations in the purification methods may influence the levels of impurities, such as aggregates, antibodies against blood group antigens, and cytokines, which may affect the safety and tolerability of the final IVIG product."
......................................................................
"According to the American Academy of Allergy, Asthma & Immunology, IVIG is not a generic drug and IVIG products are not interchangeable.1 A generic drug is a pharmaceutical drug that contains the same chemical substance as a drug that was originally protected by chemical patents. Generic drugs are allowed for sale after the patents on the original drugs expire. By law, the active ingredient in a generic drug must be the same as the original drug, but generics may include different inactive ingredients such as preservatives or fillers.
By contrast, a biosimilar is a biologic medical product that is almost an identical copy of a reference product that is manufactured by a different company. Biosimilars are officially approved versions of original “innovator” products and can be manufactured when the original product’s patent expires.
As biologic medicines, biosimilars are inherently different from generics due to their molecular size and structure, complexity, and cost of their development.
Of note, Ig is a blood product prepared from plasma of between 1,000 and 30,000 donors per batch. Commercial Ig preparations contain a “species repertoire” of antibody specificities, resulting in neutralization of a wide range of antigens, including pathogens and superantigens; however, there is significant batch-to-batch variation in the concentration of a particular antibody.
Each batch of Ig varies within each manufacturer because of variations of batch sizes and the release specifications have a broad range. The manufacturing processes from each producer differ for Ig products, resulting in products that vary pharmaceutically even though they may have similar clinical effectiveness."
..................................
https://www.pharmacytimes.com/view/rxfocuscommentary-0310 Pharmacy Times March 2010 Central Nervous System Volume 76 Issue 3 Specialty Pharmaceuticals: Immunoglobulin Therapy
Posted Jul 9, 2026, 7:53 PM UTC