RACIAL-DIFFERENCES IN THE PHARMACOKINETICS OF METHYLPREDNISOLONE IN BLACK-AND-WHITE RENAL-TRANSPLANT RECIPIENTS

Study Objective. To examine the comparative pharmacokinetics of long-t erm methylprednisolone therapy in black and white renal transplant rec ipients. Design. Comprehensive pharmacokinetic evaluations of patients who participated in our glucocorticoid-monitoring program. Setting. U niversity-based renal transplantation clinic. Patients. Six white rena l transplant recipients with stable renal function, sex- and (approxim ate) age-matched with six preselected black patients. Interventions. T he daily oral methylprednisolone dose for each patient was administere d intravenously, and serial plasma samples were obtained over 24 hours . Measurements and Main Results. Methylprednisolone was analyzed by hi gh-performance liquid chromatography. The drug's pharmacokinetics in b lack and white patients, respectively, were as follows: mean clearance 234 +/- 124 and 472 +/- 180 ml/hr/kg (p<0.05); volume of distribution 0.3-2.0 and 0.8-2.0 L/kg; and elimination rate constant 0.13-0.41 and 0.27-0.42 hour-1 (p<0.06). No statistical difference was noted in the last two parameters. The mean half-life of 3.4 +/- 1.4 hours in black patients compared with 2.1 +/- 0.3 hours in white patients approached statistical significance (p<0.08). Conclusions. These preliminary obs ervations suggest that the disposition of methylprednisolone differs b etween black and white renal transplant recipients. The current method of prescribing glucocorticoids employs a fixed-dose regimen that does not take these possible interracial differences into consideration. I ncorporating the differences may allow for more individualized dosing and more efficacious use of the agent in this patient population.