Half-life and clearance of pH 6.8 and pH 4.25 immunoglobulin G intravenous preparations in patients with primary disorders of humoral immunity.

The half-life (t1/2) and clearance of IgG and three antibodies--to tetanus, pneumococcus type 3, and pneumococcus type 7--were evaluated in 38 patients who participated in a multicenter, double-blind, crossover study comparing two immunoglobulin G intravenous preparations, IGIV pH 6.8 and the new IGIV pH 4.25. IgG metabolism was evaluated after the sixth infusion by measuring the decline in concentration of IgG and specific antibody. The t1/2 values of IgG varied greatly, but the mean values of 32 and 37 days are comparable to those determined in previous studies with use of radiolabeled IgG and are longer than those reported in normal volunteers. The t1/2 values for specific antibodies, especially those to tetanus, tended to be shorter than those for IgG. The clearance of IgG and antibodies also varied widely, but even though there was some relationship between the clearance and t1/2 in individual patients, the poor correlation (R2 less than .5) suggested that other factors, such as redistribution or loss of damaged molecules, are as important as the catabolic rate. Thus, clearance may be a more reliable parameter than t1/2 in evaluating the metabolism of IgG.

RCT Entities:   Population Interventions Outcomes