EFFECTS OF LOW-DOSE PREDNISOLONE ON CYCLOSPORINE PHARMACOKINETICS IN LIVER-TRANSPLANT RECIPIENTS - RADIOIMMUNOASSAY WITH SPECIFIC AND NONSPECIFIC MONOCLONAL-ANTIBODIES

The following study of cyclosporine pharmacokinetics was performed to investigate the effects of withdrawal of low-dose maintenance prednisolone (0.3-0.6 mg/kg body weight) from the routine immunosuppressive regimen given to 10 liver transplant recipients with stable liver function tests. After oral administration of cyclosporine (6.4-10.3 mg/kg) whole blood concentrations were measured by radioimmunoassay (RIA) with both a specific monoclonal antibody detecting parent drug and a non-specific antibody additionally detecting a cross-section of metabolites. Withdrawal of prednisolone produced no significant change in the mean time and concentration of maximum blood cyclosporine (3.3 h and 1160 μg/l, respectively), the initial and terminal elimination half-life (3.5 h and 18.4 h, respectively) and the area under the blood concentration versus time curve (AUC) measured with either the specific or non-specific monoclonal antibody. Measurements with these two antibodies indicated that the terminal elimination of cyclosporine metabolites was more rapid than for the parent drug (half-life: 14.5 vs 18.4, respectively). © 1990 Springer-Verlag.