Intravenous versus intramuscular route: How to choose

End-stage liver diseases due to HBV are among the major indications for liver transplantation worldwide and represent a peculiar issue in Italy where they can be as high as 25%. The widespread use of long-term prophylaxis with hepatitis B immunoglobulin (HBIG), either alone or in combination with antiviral drugs in the post-liver transplant period, has significantly improved both graft and patient survival. HBIG prophylaxis is usually administered intravenously, or intramuscularly The two formulations present a peculiar difference in their pharmacokynetics: peak serum concentrations after intravenous administration are observed within 2 hours, whereas intramuscular injection of HBIG provides peak serum concentrations between day 5 and 11. However, long-term intravenous prophylaxis is expensive and time-consuming. In order to determine when and how to choose between intravenous or intramuscular route, the anhepatic phase is crucial for the potential risk of graft infection and for which a management strategy that specifically addresses the virological status and history of the patient should be adopted. During the first week post-transplantation, high-dose protocols are traditionally applied, although the ideal, patient-tailored protocols should be defined on the basis of both viral and patient-related features. After the first week post-transplantation, available evidence clearly indicates that the type of formulation has little or no effect on the prophylactic regimen, and lower doses of HBIG appear to be needed when given in combination with nucleos(t)ide analogues.