Comparative pharmacokinetics of liquid and lyophilized formulations of IV RhIG immune globulin

To compare the pharmacokinetics, safety, and tolerability of the liquid and lyophilized formulations of Rh(0)(D) immune globulin intravenous (human) (IV RhIG) administered intramuscularly (IM) and intravenously (IV). In 2 randomized, parallel arm, blinded, phase I studies, 142 healthy adult volunteers received a single dose of either the liquid or lyophilized formulation administered IM (300 microg in Study 1; 15 microg/kg in Study 2) or IV (50 microg/kg in Study 1). Pharmacokinetics (area under the curve [AUC}, C(max), t(1/2), T(max)) and safety data were assessed over 84 days. The 2 formulations had comparable pharmacokinetics following both IM and IV administration. The ratios (90% confidence intervals) for AUC and C(max) treatment means were, for most assessments, within the predefined FDA acceptance range of 80%-125%, demonstrating the bioequivalence of the liquid and lyophilized formulations. Both formulations were equally well tolerated. Study results demonstrate comparable safety and pharmacokinetic profiles of the liquid and lyophilized formulations of IV RhIG. These findings suggest that the liquid formulation will be therapeutically equivalent to the lyophilized formulation but in a more convenient ready-to-use dosage form that may also reduce preparation errors.