SCIG offers many patients a viable, convenient alternative to IVIG. A logical step forward from the successful use of SCIG in replacement therapy is the use of SCIG in the setting of immunomodulation. Multi-focal motor neuropathy (MMN) is known to be responsive to IVIG therapy. MMN is a serious autoimmune neuropathy characterized by segmental demyelination, conduction block and asymmetric weakness, with relatively preserved muscle bulk. MMN is associated with anti-GM1 antibodies in 50–80% of cases.
Three recent studies of SCIG in patients selleck screening library with MMN who were switched from IVIG show that SCIG was as efficacious as IVIG, as measured by combined dynamometric  and the Medical Research Council (MRC) muscle strength click here scores . In a more recent study, patients were switched gradually over 3 weeks from IVIG to SCIG . The majority of patients maintained MRC muscle strength score over the 6-month study. In all three studies, the majority of patients elected to continue SCIG administration at the end
of the study (Table 2). One patient who experienced muscle strength deterioration also continued to use this form of administration . Thus, SCIG showed good efficacy, was preferred by patients with MMN and its use in immunomodulation should be investigated further. SCIG may also be effective in dermatological autoimmune disorders as demonstrated in IVIG-responsive epidermolysis bullosa acquisita (EBA). A case report Histidine ammonia-lyase study of a patient with EBA who was switched to SCIG (0·9 g/kg/month) showed improved clinical outcome . Successful treatment of MMN and EBA suggests that SCIG use can be explored in many other conditions where IVIG is effective. A recent retrospective study offers insight into new ways to improve convenience in SCIG administration. Infusion with a syringe and butterfly needle (rapid push) was compared with the usual pump administration. The rapid push method involves more frequent subcutaneous administration of smaller doses compared
to weekly SCIG. Of 104 patients with PI who had either no previous IgG therapy or had been on IVIG, 74 patients used rapid push administration and 29 used a pump to infuse a 16% SCIG IgG formulation. Patients using rapid push underwent an average of 3·1 infusions per week, and those using pump an average of 2·9 infusions per week. Rapid push was found to be an efficacious alternative, as no difference in mean serum IgG levels was observed between the two different administration methods . Additionally, serum IgG levels achieved with either route of SCIG infusion were higher than those achieved with the previous IVIG therapy, due probably to the frequent administration of smaller doses and the slow transition of IgG into the vascular space. Rapid push infusion thus offers a suitable alternative, for example, when a pump is not available or when high infusion volumes per injection site are not tolerated.