Effect of CYP2C19 polymorphisms on the clinical outcome of low-dose clobazam therapy in Japanese patients with epilepsy.

[Purpose]Clobazam (CLB) is metabolized by cytochrome P450 (CYP) 3A4 to yield N-desmethylclobazam (N-CLB), which is further inactivated by CYP2C19. The aim of this study was to retrospectively evaluate the relationship between CYP2C19 polymorphisms and the efficacy of low-dose, add-on CLB therapy in Japanese patients with epilepsy. [Methods]Fifty patients were divided into three groups according to their CYP2C19 polymorphism. CLB and N-CLB serum concentrations and seizure frequency before and after starting CLB were analyzed. [Results]Extensive metabolizers (EMs, n = 11), intermediate metabolizers (IMs, n = 22), and poor metabolizers (PMs, n = 17) were included. Although the dose-normalized CLB serum concentrations were not significantly different, the dose-normalized N-CLB serum concentrations were significantly higher in PMs than in EMs or IMs. Seizure frequency was significantly decreased by the CLB therapy in PMs (p < 0.01), but not in EMs or IMs. CLB serum concentrations did not correlate with seizure reduction rate, but median N-CLB serum concentrations were significantly higher in patients with excellent seizure control (≧90 % seizure reduction) compared to those with ≧50 % seizure reduction or with <50 % seizure reduction (1103, 341, and 570 ng/mL, respectively). [Conclusions]The efficacy of low-dose CLB therapy was significantly influenced by CYP2C19 polymorphisms. Ideally, CLB therapy should be started with a low dose (2.5 mg/day) and dosage increased until N-CLB serum concentration reaches 1100 ng/mL or until the desired effect is acquired, a recommendation that is particularly important for PMs

Effectiveness of Sirolimus in Combination with Cyclosporine against Chronic Rejection in a Pediatric Liver Transplant Patient

The patient is a 3-year-old boy who received living-donor liver transplantation (LDLT) for hepatoblastoma, with his mother as the donor. Oral tacrolimus was started at a dose of 0.3 mg every 12 h from day 1, with the dosage adjusted on the basis of trough concentrations. The levels of aspartate aminotransferase (AST), alanine transferase (ALT), and total bilirubin (T-bil) were 110 U/L, 182 U/L, and 12.6 mg/dL, respectively, when chronic rejection (CR) was pathologically diagnosed. Then, sirolimus at a dose of 1.0 mg/d was added to the tacrolimus-based regimen. The T-bil level rapidly decreased to 5.4 mg/dL, without changes in AST and ALT. Because the intracellular receptor of sirolimus and tacrolimus is FK506-binding protein 12, we switched tacrolimus to cyclosporine at a dose of 60 mg/d to avoid competitive inhibition between these 2 drugs. The target trough concentration of sirolimus and cyclosporine was set to around 15 ng/mL and 180 ng/mL, respectively. The concentration/dose ratio of sirolimus was significantly correlated with the blood cyclosporine level (r=0.5293, p<0.05), suggesting the pharmacokinetic interaction between these 2 drugs. Thereafter, the levels of AST and ALT as well as the T-bil were successfully decreased to 73 U/L, 83 U/L, and 3.0 mg/dL, respectively. These results suggest that sirolimus therapy in combination with cyclosporine may be an effective treatment against CR after liver transplantation

Effectiveness of Sirolimus in Combination with Cyclosporine against Chronic Rejection in a Pediatric Liver Transplant Patient

The patient is a 3-year-old boy who received living-donor liver transplantation (LDLT) for hepatoblastoma, with his mother as the donor. Oral tacrolimus was started at a dose of 0.3 mg every 12 h from day 1, with the dosage adjusted on the basis of trough concentrations. The levels of aspartate aminotransferase (AST), alanine transferase (ALT), and total bilirubin (T-bil) were 110 U/L, 182 U/L, and 12.6 mg/dL, respectively, when chronic rejection (CR) was pathologically diagnosed. Then, sirolimus at a dose of 1.0 mg/d was added to the tacrolimus-based regimen. The T-bil level rapidly decreased to 5.4 mg/dL, without changes in AST and ALT. Because the intracellular receptor of sirolimus and tacrolimus is FK506-binding protein 12, we switched tacrolimus to cyclosporine at a dose of 60 mg/d to avoid competitive inhibition between these 2 drugs. The target trough concentration of sirolimus and cyclosporine was set to around 15 ng/mL and 180 ng/mL, respectively. The concentration/dose ratio of sirolimus was significantly correlated with the blood cyclosporine level (r=0.5293, p<0.05), suggesting the pharmacokinetic interaction between these 2 drugs. Thereafter, the levels of AST and ALT as well as the T-bil were successfully decreased to 73 U/L, 83 U/L, and 3.0 mg/dL, respectively. These results suggest that sirolimus therapy in combination with cyclosporine may be an effective treatment against CR after liver transplantation

Significance of trough monitoring for tacrolimus blood concentration and calcineurin activity in adult patients undergoing primary living-donor liver transplantation.

[Purpose] : Tacrolimus pharmacokinetics and calcineurin activity in peripheral blood mononuclear cells (PBMCs) were investigated in adult patients undergoing primary living-donor liver transplantation (LDLT) in order to clarify the significance of monitoring the tacrolimus blood trough concentration during the early post-transplantation period. [Methods] : Fourteen patients were enrolled in this study, and time-course data following the oral administration of a conventional tacrolimus formulation twice daily were obtained at 1 and 3 weeks post-transplantation. The concentration of tacrolimus in whole blood and calcineurin activity in PBMCs were measured. [Results] : The apparent clearance of tacrolimus significantly increased at 3 weeks versus 1 week post-transplantation, although the trough concentration did not significantly differ at these time points. The concentration at each sampling time, except at 1 h post-dose, correlated well with the area under the concentration–time curve from 0 to 12 h (AUC0–12). Neither the concentration at the trough time point nor AUC0–12 was correlated with the area under the calcineurin activity–time curve from 0 to 12 h; however, calcineurin activity at the trough time point was strongly correlated with the latter (r 2 > 0.92). [Conclusions] : Based on these results, trough concentration monitoring can be considered an appropriate procedure for routine tacrolimus dosage adjustment in adult LDLT patients. Monitoring of calcineurin activity at the trough time point was also found to be potentially useful for predicting the immunological status of the patient during the tacrolimus dosing interval