Differentiating Characteristics and Evaluating Intravenous, Subcutaneous Immunoglobulin

In a Pharmacy Times® Continuing Education Supplement, Stacey Ness, PharmD, RPh, CSP, MSCS, AAHIVP, examined the differences between intravenous and subcutaneous immunoglobulin, including their intended patient populations, risks, and benefits.

Traditionally, intravenous immunoglobin (IVIG) administration has provided effective therapy for a variety of disease states. However, with the more recent use of subcutaneous immunoglobin (SCIG), treatment options for patients with several conditions, such as primary immunodeficiency diseases or chronic inflammatory demyelinating polyneuropathy (CIDP) have significantly grown.

Other forms of this treatment include recombinant human hyaluronidase-facilitated SCIG as a treatment option for primary immunodeficiency diseases. However, it is important that clinicians understand the intended patient population for these treatment options, as well as benefits and risks.

The American Academy of Allergy, Asthma, and Immunology (AAAAI) has established a list of 8 guiding principles to help clinicians make quality decisions regarding IVIG for patients with primary immunodeficiency. Although the AAAAI’s principles are directed at IVIG for primary immunodeficiency, many points also translate to SCIG therapy and other FDA-approved indications, such as CIDP or multifocal motor neuropathy.

They are as follows:

--Indication (IVIG therapy is indicated as replacement therapy for patients with PI characterized by absent or deficient antibody production)

--Diagnoses

--Frequency of IVIG treatment

--Dose

--IgG trough levels

--Site of care (hospital, hospital outpatient, community office)

--Route of administration based on patient characteristics

--Product characteristics, such as whether the product is intended for a single route of administration

Another pertinent resource for clinicians is the Immunoglobulin Therapy Standards of Practice published by the Immunoglobulin National Society (IgNS), which is in its second edition.

The mechanism of action for use of Ig in the treatment of autoimmune disorders is complex and partially understood, but immunomodulatory effects have been suggested in CIDP and multifocal motor neuropathy. Furthermore, the available IVIG and SCIG products differ in their pharmaceutical properties (eg, pH, osmolality, IgA content, sodium content, and stabilizer), which can affect safety and tolerability in some patients.

Determining the best Ig treatment option for a given patient requires an assessment of the risks and benefits of each product. When an initial assessment has been completed and it is found that IVIG and SCIG would both be feasible for a patient, additional factors, including adverse event (AEs) profiles, dosing frequency, and pharmacokinetics (PK), can be considered.

For example, the PK of Ig also differ based on the route of administration. With IVIG administration every 3 or 4 weeks, peak concentrations are greater and trough concentrations are lower, which can increase the propensity of systemic AEs and affect tolerability of therapy. SCIG infusions are typically administered more frequently (ie, biweekly, weekly, and even daily based on patient need), resulting in steady state concentrations with fewer fluctuations in Ig plasma levels.

The route of administration plays a major role in the types of AEs seen in patients receiving Ig therapy, with systemic AEs associated with IV administration and local reactions more commonly seen with SC administration. By understanding the differences in IVIG and SCIG products, which are not interchangeable, and the patient characteristics that guide product selection, clinicians and managed care providers can better serve patients with immunodeficiency disorders and other disease states.

Whether administered via the IV or SC route, successful Ig therapy depends on expert clinical knowledge and experience, as well as a collaborative health care environment. IV and SC are both clinically appropriate modes of administering Ig to patients with primary immunodeficiency disorders and other autoimmune disease states. Each mode of administration has advantages and disadvantages but remains a patient-specific choice.

To read the full Continuing Education article, visit the Pharmacy Times® website.