Pharmacokinetics of orally administered tacrolimus in lupus nephritis patients

Abstract

The pharmacokinetics of orally administered tacrolimus were examined in six female lupus nephritis patients (mean age 43 years, range 24-55 years). Tacrolimus (3 mg) was administered after supper, and blood tacrolimus concentrations were measured just prior to dosing and 1, 2, 4, 6, 8, 12 and 24 h after administration. The maximum blood concentration (Cmax) was observed 4-8 h (mean: 6.7 h) after administration. The mean Cmax and area under the tacrolimus concentrationti-me curve (AUC0-24 h) were 12.7 ng/ml and 163.1 ng·h/ml, respectively. Although there was a weak correlation between AUC0-24 h values and tacrolimus concentrations 2, 4, and 6 h after administration, concentrations at 12 and 24 h were highly correlated with AUC0-24 h values, suggesting that the trough concentration (C24 h) and C12 h are valid markers for therapeutic tacrolimus monitoring. Enzyme-linked immunoabsorbent assay (ELISA) and microparticle enzyme immunoassay (MEIA) measurements of blood tacrolimus concentrations were similar. We recommend that monitoring should be carried out by C12 h in lupus nephritis outpatients. © 2010 The Pharmaceutical Society of Japan.