Pharmacokinetics of mizoribine in adult living donor liver transplantation

We investigated the pharmacokinetics of mizoribine in the acute phase after adult living donor liver transplantation (LDLT). Between February 2004 and October 2009, 16 recipients received immunosuppressive therapy that included mizoribine (100 to 200 mg/d) after undergoing LDLT. We determined the serum levels of mizoribine before (C0) and 3 (C3), 4 (C4), and 10 (C10) hours after administration on postoperative days 3, 7, and 21. We assessed area under the concentration time curve (AUC) (hour · μg/mL), normalized serum concentration (NSC) at C0 [concentration (μg/mL)/dose (mg/kg body weight)], and estimated glomerular filtration rate (eGFR). The mizoribine concentration showed increases at C3 and C4 followed by a decrease at C10 on all days. AUC was 4.3, 5.9, and 8.3 in the 200-mg/d dose group on days 3, 7, and 21, respectively. NSC at C0 increased for 3 weeks after LDLT. There was a significant correlation between the NSC at C0 and eGFR on day 21, but not on days 3 and 7. There were no correlations between the NSC at C0 and either aspartate aminotransferase, total bilirubin, albumin, trough cyclosporine, or trough tacrolimus on any day. The pharmacokinetics of mizoribine in the acute phase after LDLT seems to be affected by postoperative day and renal function.