What is IVIG/SCIG?
The goal of Ig therapy for antibody disorders, no matter the route of administration, is to provide protection from infection. An individual’s adherence to therapy is paramount to achieving this goal. Any barriers to therapy, real or potential, need to be addressed appropriately.
Immunoglobulin or Ig, also known as gamma globulin or immune globulin, refers to the liquid plasma component of blood that contains immunoglobulins or antibodies. These antibodies have the important role in the immune system of neutralizing bacteria and viruses, and enhancing the phagocytosis and destruction of bacteria, certain viruses, and other pathogens.
Your body’s immune system normally makes enough antibodies to fight germs that cause infections. But if you have an immune deficiency, your body can’t make enough of them. This puts you at greater risk for infections. Ig therapy gives you antibodies that your body is not making on its own so you can fight infections.
Immunoglobulin is part of your blood’s plasma. When people donate blood, this part can be separated out and pooled together with the Ig from thousands of other donors. Then it can be given to you through a vein in your arm or subcutaneously.
The liquid immunoglobulin taken from the blood plasma of donors is screened and tested for serious infections like hepatitis and AIDS. The plasma is purified before it is used for Ig therapy.
Differences between IVIG and SCIG
Ig therapy is generally administered either intravenously (abbreviated IVIG), or subcutaneously (abbreviated SCIG). There are advantages and disadvantages for each route of administration. Patients should talk to their healthcare provider to determine which route of administration is best for them.
IVIG allows the infusion of higher doses over a short time and historically has been the standard route of administration. It must be administered by a healthcare professional.
IVIG is given through a vein every three to four weeks at a dose determined by the prescriber. Infusions can be given in various settings including an inpatient or outpatient infusion suite, physician office, or in the home. IVIG is administered by a healthcare professional, and the procedure is scheduled in advance. IVIG infusions typically take 4 or more hours.
SCIG is usually infused under the skin, into the subcutaneous layer of the abdomen, thighs, or outer buttocks at one or multiple sites, depending on the volume being infused. SCIG is typically given every week because the doses are lower.
In general, SCIG regimens require the individual with PI or caregiver to learn how to self-administer at home. SCIG infusions typically take 1-2 hours to complete.
Ig therapy is typically dosed based on the recipient’s weight. Many factors, however, are considered when the medication is prescribed. Typically, a starting dose is between 400 to 600mg/ kg/month. Doses are adjusted for clinical efficacy, with the expectation of minimizing the frequency and severity of recurrent infections while minimizing side effects of the medication. Ig levels are usually monitored over time and correlated with the response to therapy.