When is IVIG Not Used
IVIG is replacing immunoglobulin G only. Patients with IgA and/or IgM deficiency don’t benefit from replacement unless they have associated IgG defect.
How and Where IVIG administered?
IVIG can be given intravenously or subcutaneously. Immunoglobulin given by intravenous route is called IVIG and that given by subcutaneously is called SCIG. IVIG is given every 3-4 weeks and usually given in hospital settings or infusion centers. There is increasing use of IVIG given in home setting for patients who don’t experience side effects after initial infusion.
SCIG has been used longer in Europe than US.But its use in increasing due to convenience and less side effects. SCIG is given weekly usually under the skin in the abdominal wall. A recent formulation of SCIG called HYQVIA is given subcutaneously every month.
Dose of Replacement Immunoglobulin
Traditionally the dose of 300-500mg/kg every 3-4 weeks for IVIG or 100-150mg/kg for SCIG is felt to be sufficient. Recently it has realized that IVIG dose should be adjusted such as to keep the patient infection free,even if it means to use a higher dose. To achieve the goal, patient may need IV dose may be as little as 200mg/kg every 4 weeks or 500mg/kg every 2 weeks.
Side Effects of IVIG
Most common side effects are headache, fever, muscle ache, nausea, vomitting, chills and flushing. These can occur in up to 20% of the patients. These are treated with stopping the infusion, decreasing the rate of infusion and/or using antihistamines, tylenol and prednisone prior to infusions.
Flushing and/or hives are common. Some patients tolerate one product better than other.
Potentially serious side effects includes adverse effect on kidney, blood (break down of different kind of blood cells leading to low hemoglobin, low white cell count), brain (migraine and aseptic meningitis) and tendency for the blood to clot (more with high dose therapy which is not used in patients for immunodeficiency) as well as anaphylaxis in a rare patient. Many of these are reduced by slow infusion rates, choosing appropriate formulation of IVIG and/or switching to SCIG.
IVIG vs SCIG
In general, side effects of infusion are more often and more severe with intravenous formulations, but have occured with when immunoglobulins are infused subcutaneously.
Risk of Transmission of Blood Borne Pathogen
All products available in US are made from plasma collected from US donors and are free from all known pathogens. Various measures which have made immunoglobulin safe are:
- Careful donor selection and screening
- Test of each plasma sample for evidence of infection
- Donated units of plasma are quarantined. This means these will not be used same donor donate blood again and second unit of blood is found to be free of infection, one would the first unit of plasma
- Each manufacturer must employ multiple methods to inactivate the virus or remove it
Monitoring of Patients on Immunoglobulin Therapy
Patients on treatment are regularly monitored to assess
- Whether the desired effect is achieved i.e. is the infection rate acceptable or not
- The side effects of the treatment
- Periodic monitoring of blood parameters to assess blood counts, liver and kidney functions as well as immunoglobulin level in the blood
How Long IVIG Treatment Lasts?
Some patients with primary immunodeficiency like agammaglobulinemia need life long infusions while patients with Rituxan induced low immunoglobulin or patients with transient hypogammaglobulinemia may recover after few years and IVIG may be discontinued.