CLINICAL PHARMACOLOGY
GAMMAGARD S/D, Immune Globulin Intravenous (Human), contains a broad spectrum of IgG antibodies against bacterial and viral agents that are capable of opsonization and neutralization of microbes and toxins.
Peak levels of IgG are reached immediately after infusion of GAMMAGARD S/D. It has been shown that, after infusion, exogenous IgG is distributed relatively rapidly between plasma and extravascular fluid until approximately half is partitioned in the extravascular space. Therefore, a rapid initial drop in serum IgG levels is to be expected.4 As a class, IgG survives longer in vivo than other serum proteins. 4,5 Studies show that the half-life of GAMMAGARD S/D is approximately 37.7 ± 15 days. 3 Previous studies reported IgG half-life values of 21 to 25 days. 4,5,6 The half-life of IgG can vary considerably from person to person, however. In particular, high concentrations of IgG and hypermetabolism associated with fever and infection have been seen to coincide with a shortened half-life of IgG. 4-7
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