Subcutaneous Immunoglobulin-G Replacement Therapy with Preparations Currently Available in the United States for Intravenous or Intramuscular Use: Reasons and Regimens

For patients who require replacement therapy for primary immunodeficiency, subcutaneous infusions of immunoglobulin G (IgG) may be preferable to intravenous infusions for several reasons. However, at present, there is no preparation marketed for use by this route in North America. In this article, we describe the reasons patients have selected this route of therapy and the range of treatment regimens used. Approximately 20% of our patients have chosen the subcutaneous route, mainly because of adverse effects from intravenous (IV) infusions or difficulties with venous access. Unit dose regimens using whole bottles of currently available 16% intramuscular preparations or sucrose-containing lyophilized preparations intended for IV use but reconstituted to 15% IgG for subcutaneous administration were individually tailored to each patient. In most cases, self-infusions or home infusions were administered once or twice a week, most commonly requiring two subcutaneous sites and 2 to 3 hours per infusion. On average, patients took 0.18 mL of IgG per kilogram of body weight per site per hour. There were no systemic adverse effects. In patients for whom comparative data were available, trough serum IgG levels were higher with subcutaneous therapy than with IV therapy.