Comparison of immune reactivity and pharmacokinetics of two hepatitis B immune globulins in patients after liver transplantation

Hepatitis B virus (HBV) immune globulin (HBIg) administration will prevent HBV graft reinfection in HBV patients after orthotopic liver transplantation (OLT). However, the expenditure for such prophylaxis is extremely high ranging between $2,000 to $10,000 per month in various countries for an undefined period and presumably for life. As a consequence, there is a need for introduction of additional and less expensive modes of treatment. In a preliminary clinical trial a new HBIg preparation has been shown to induce longer lasting levels of circulating antibodies to hepatitis B surface antigen (anti-HBs) in patients after OLT compared with previous experience with conventional HBIg preparations. In the present study the pharmacokinetics of this new HBIg, OMRI-Hep-B, were studied and compared with a conventional, licensed preparation, Hepatect. Fifteen post-OLT patients (2- 8 years post-OLT, 18-62 years of age, 6 men, 9 women) were treated intravenously with 49 doses of OMRI-Hep-B or Hepatect given at least once, alternately, at 10,000 to 14,000 units per injection (≃130 IU/kg body weight). The new HBIg was well tolerated and no adverse effects were observed. Administration of OMRI-Hep-B was shown to induce high and long- lasting levels of circulating anti-HBs antibodies and greater areas under the curve (AUC) compared with the conventional preparation. Thus, anti-HBs half- life was 22 ± 1.3 days for OMRI-Hep-B recipients and 13 ± 1.3 days for Hepatect recipients (P .001). Time to reach trough anti-HBs levels of 150 mIU/mL was significantly longer after administration of OMRI-Hep-B than after Hepatect (79 ± 4.5 and 52± 3.8 days, respectively; P < .001). In summary, the pharmacokinetic profile of the new HBIg, and in particular its prolonged elimination half-life, may reduce the cost of administration by approximately 30% and improve the quality of life of patients by extending the interval between repeated immune globulin injections.