Masahide Fukudo

Kyoto University, Kyoto, Kyoto-fu, Japan

Are you Masahide Fukudo?

Claim your profile

Publications (26)90.67 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Sunitinib, a multitargeted tyrosine kinase inhibitor, offers favorable therapeutic outcomes to patients with advanced renal cell carcinoma. However, to maximize the clinical benefits, an effective therapeutic management strategy with dose optimization is essential. The objectives of this analysis were to describe the pharmacokinetics (PK) of sunitinib by a population PK approach and to quantitatively evaluate the effect of potential predictive factors including ABCG2 genotype on the PK of sunitinib. Plasma concentration-time profiles at 3 consecutive days including a total of 245 sunitinib plasma concentrations were available from 19 Japanese patients with renal cell carcinoma. Blood samples were collected on days 2, 8, and 15 after the start of the therapy. Population PK analysis was performed using NONMEM 7.2. Body weight, gender, and genotype of ABCG2 421C>A were evaluated as potential covariates. Interoccasion variability (IOV) among the 3 sampling days was also assessed as a random effect parameter. The sunitinib PK profiles were best described by a 1-compartment model with first-order absorption. The ABCG2 421C>A genotype was identified as a significant covariate for the prediction of oral clearance (CL/F). No significant improvement in model fit was observed by including body weight and/or gender. A systematic difference in estimated population CL/F was observed between days 2 and 8, which was quantified as approximately 30% decrease over time. This difference was described as a covariate for CL/F in the model. IOV included as a random effect parameter significantly improved the model fit. This analysis provides a population PK model of sunitinib with the ABCG2 421C>A genotype as a predictive covariate for CL/F. It also suggests that IOV and change of CL/F over time need to be considered to predict the sunitinib PK more accurately. These findings will be implemented to optimize the pharmacotherapy of sunitinib.
    Therapeutic drug monitoring 06/2014; 36(3):310-6. · 2.43 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Sorafenib has various adverse events that can cause treatment discontinuation or dose reduction. The aim of this study was to compare the safety profile between renal cell carcinoma (RCC) and hepatocellular carcinoma (HCC) patients receiving sorafenib under real-life practice conditions. Furthermore, we investigated the relationship between sorafenib exposure and clinical outcomes. A total of 91 Japanese cancer patients (RCC, n = 21; HCC, n = 70) treated with sorafenib were enrolled. Toxicity was graded according to the National Cancer Institute Common Toxicity Criteria for Adverse Events (NCI-CTCAE) version 4.0. Single blood samples were collected at each clinic visit and serum sorafenib concentrations were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The incidence of adverse events was analyzed according to cancer type and sorafenib concentration. Hand-foot skin reaction (HFSR) was the most common adverse event among RCC (76 %) and HCC (66 %) patients. Elevations in hepatic transaminases and pancreatic amylase developed more frequently in patients with RCC than in those with HCC (p < 0.05), while hyperbilirubinemia and thrombocytopenia were observed more often in HCC patients than in RCC patients (p < 0.05). Pharmacokinetic data were available from 52 patients (RCC, n = 16; HCC, n = 36). HCC patients showed significantly higher dose-normalized concentrations than RCC patients (p = 0.0184). Sorafenib concentrations were significantly greater in patients with grade ≥2 HFSR and hypertension than in those not experiencing the adverse events (p = 0.0045 and 0.0453, respectively). Furthermore, receiver operating characteristic curves revealed optimal cutoff concentrations of sorafenib to predict grade ≥2 HFSR (5.78 μg/mL) and hypertension (4.78 μg/mL). In addition, a trend of prolonged overall survival was observed in HCC patients who achieved a maximal sorafenib concentration of ≥4.78 μg/mL during treatment compared with those who did not achieve the threshold concentration (12.0 vs. 6.5 months; log-rank p = 0.0824). The results of this study suggest that the safety and pharmacokinetic profiles of sorafenib differ between Japanese cancer patients with RCC and HCC. Furthermore, the serum sorafenib concentration could be used as a guide to avoiding the development of severe HFSR while allowing prediction of the incidence of grade ≥2 hypertension in patients with RCC and HCC, and may potentially be related to the clinical efficacy of sorafenib for HCC.
    Clinical Pharmacokinetics 10/2013; · 5.49 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The aim of this study was to elucidate the roles of P-glycoprotein (P-gp/ABCB1) and breast cancer resistance protein (BCRP/ABCG2) in the plasma concentration, biliary excretion, and distribution to the liver, kidney, and brain of sunitinib. The pharmacokinetics of sunitinib was examined in rats treated with PSC833 and pantoprazole, potent inhibitors of P-gp and BCRP, respectively. The sunitinib concentrations in plasma, bile, liver, kidney, and brain were determined by liquid chromatography-tandem mass spectrometry. The tissue to plasma concentration ratio (Kp, tissue) was calculated. It was found that the area under the concentration-time curve for 4 hours (AUC0-4) and maximum concentration (Cmax) of sunitinib administered intraintestinally were significantly increased by pretreatment with PSC833 or pantoprazole. Each inhibitor markedly reduced the biliary excretion of sunitinib for 60 min after an intravenous administration and significantly increased Kp, liver, as well as Kp, kidney. The Kp, brain of sunitinib was significantly increased by PSC833 but not pantoprazole, and co-administration of both inhibitors further enhanced the accumulation of sunitinib in the brain. These results demonstrate that plasma concentrations of sunitinib and the biliary excretion and distribution to the kidney, liver, and brain of sunitinib are influenced by pharmacological inhibition of P-gp and/or BCRP.
    Drug metabolism and disposition: the biological fate of chemicals 06/2013; · 3.74 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The efficacy of sorafenib against hepatocellular carcinoma (HCC) has been extensively reported. However, there is little information available about the use of sorafenib for HCC patients with end-stage renal failure. We herein report the safe introduction of sorafenib therapy for a HCC patient on hemodialysis. A 63-year-old male had received multidisciplinary treatments, including transarterial chemoembolization (TACE) and radio frequency ablation, for HCC since 1996, and had been undergoing hemodialysis since 2005. He also underwent TACE for multiple liver recurrence of HCC in 2011. Sorafenib therapy (200 mg/day) started eight days after the TACE. The pharmacokinetic parameters of sorafenib and its active metabolite, M-2, were within the reference levels observed in patients with normal renal function eight and nine days after the initiation of sorafenib. The dose of sorafenib was reduced to 200 mg every other day on day 154 due to hypertension and general fatigue. Because of the progression of disease after five months, sorafenib was withdrawn on day 180. He was admitted to the emergency department because of a high fever during hemodialysis on day 201, and died of septic shock induced by Staphylococcus lugdunensis on day 203. Sorafenib was well tolerated at an initial dose of 200 mg/day for an HCC patient undergoing hemodialysis, thus indicating that renal failure is not necessarily a contraindication for sorafenib therapy.
    Hepatology Research 05/2013; · 2.07 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: BACKGROUND: Erlotinib shows large inter-patient pharmacokinetic variability, but the impact of early drug exposure and genetic variations on the clinical outcomes of erlotinib remains fully investigated. The primary objective of this study was to clarify the population pharmacokinetics/pharmacodynamics of erlotinib in Japanese patients with non-small cell lung cancer (NSCLC). The secondary objective was to identify genetic determinant(s) for the cerebrospinal fluid (CSF) permeability of erlotinib and its active metabolite OSI-420. METHODS: A total of 88 patients treated with erlotinib (150 mg/day) were enrolled, and CSF samples were available from 23 of these patients with leptomeningeal metastases. Plasma and CSF concentrations of erlotinib and OSI-420 were measured by high-performance liquid chromatography with UV detection. Population pharmacokinetic analysis was performed with the nonlinear mixed-effects modelling program NONMEM. Germline mutations including ABCB1 (1236C>T, 2677G>T/A, 3435C>T), ABCG2 (421C>A), and CYP3A5 (6986A>G) polymorphisms, as well as somatic EGFR activating mutations if available, were examined. Early exposure to erlotinib and its safety/efficacy relationship were evaluated. RESULTS: The apparent clearance of erlotinib and OSI-420 were significantly decreased by 24 and 35 % in patients with the ABCG2 421A allele, respectively (p < 0.001), while ABCB1 and CYP3A5 polymorphisms did not affect their apparent clearance. The ABCG2 421A allele was significantly associated with increased CSF penetration for both erlotinib and OSI-420 (p < 0.05). Furthermore, the incidence of grade ≥2 diarrhea was significantly higher in patients harboring this mutant allele (p = 0.035). A multivariate logistic regression model showed that erlotinib trough (C0) levels on day 8 were an independent risk factor for the development of grade ≥2 diarrhea (p = 0.037) and skin rash (p = 0.031). Interstitial lung disease (ILD)-like events occurred in 3 patients (3.4 %), and the median value of erlotinib C0 levels adjacent to these events was approximately 3 times higher than that in patients who did not develop ILD (3253 versus 1107 ng/mL; p = 0.014). The objective response rate in the EGFR wild-type group was marginally higher in patients achieving higher erlotinib C0 levels (≥1711 ng/mL) than that in patients having lower erlotinib C0 levels (38 versus 5 %; p = 0.058), whereas no greater response was observed in the higher group (67 %) versus the lower group (77 %) within EGFR mutation-positive patients (p = 0.62). CONCLUSIONS: ABCG2 can influence the apparent clearance of erlotinib and OSI-420, and their CSF permeabilities in patients with NSCLC. Our preliminary findings indicate that early exposure to erlotinib may be associated with the development of adverse events and that increased erlotinib exposure may be relevant to the antitumor effects in EGFR wild-type patients while having less of an impact on the tumor response in EGFR mutation-positive patients.
    Clinical Pharmacokinetics 03/2013; · 5.49 Impact Factor
  • Iryo Yakugaku (Japanese Journal of Pharmaceutical Health Care and Sciences). 01/2013; 39(9):565-570.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Several cases have been reported in which central nervous system (CNS) metastases of non-small cell lung cancer (NSCLC) resistant to gefitinib were improved by erlotinib. However, there has been no study in which cerebrospinal fluid (CSF) concentrations of gefitinib and erlotinib are directly compared. Thus, we aimed to compare them. We examined 15 Japanese patients with NSCLC and CNS metastases with epidermal growth factor receptor gene mutations who received CSF examinations during epidermal growth factor receptor-tyrosine kinase inhibitors treatment (250 mg daily gefitinib or 150 mg daily erlotinib). Plasma and CSF concentrations were determined using high-performance liquid chromatography with tandem mass spectrometry. The concentration and penetration rate of gefitinib (mean ± standard deviation) in the CSF were 3.7 ± 1.9 ng/mL (8.2 ± 4.3 nM) and 1.13 ± 0.36 %, respectively. The concentration and penetration rate of erlotinib in the CSF were 28.7 ± 16.8 ng/mL (66.9 ± 39.0 nM) and 2.77 ± 0.45 %, respectively. The CSF concentration and penetration rate of erlotinib were significantly higher than those of gefitinib (P = 0.0008 and <0.0001, respectively). The CNS response rates of patients with erlotinib treatment were preferentially (but not significantly) higher than those with gefitinib treatment. (1/3 vs. 4/7, respectively). Leptomeningeal metastases in one patient, which were refractory to gefitinib, dramatically responded to erlotinib. This study suggested that higher CSF concentration could be achieved with erlotinib and that erlotinib could be more effective for the treatment for CNS metastases, especially leptomeningeal metastases, than gefitinib.
    Cancer Chemotherapy and Pharmacology 07/2012; 70(3):399-405. · 2.80 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To elucidate the impact of genetic variations in breast cancer resistance protein (BCRP/ABCG2) and P-glycoprotein (MDR1/ABCB1) on pharmacokinetics of sunitinib, we carried out a pharmacogenetic study in a clinical setting and pharmacokinetic analysis using Abcg2(-/-), Abcb1a/1b(-/-) and Abcb1a/1b;Abcg2(-/-) mice. Nineteen renal cell carcinoma patients were enrolled in this study. The plasma concentrations of sunitinib and its active metabolite were determined and the area under the concentration-time curve (AUC) was calculated. Genetic polymorphisms in ABCG2 (421C>A) and ABCB1 (1236C>T, 2677G>T/A and 3435C>T) were examined. The dose-adjusted AUC(0-24) of sunitinib was significantly higher in patients with a heterozygous variant for ABCG2 421C>A than in wild-type patients (p=0.02), and one homozygous patient showed the highest dose-adjusted AUC(0-24). The ABCB1 polymorphisms were not associated with the dose-adjusted AUC(0-24). The maximum concentration and AUC(0-4) of sunitinib were significantly higher in Abcg2(-/-), Abcb1a/1b(-/-) and Abcb1a/1b;Abcg2(-/-) mice than wild-type mice when sunitinib was given orally but not intraperitoneally. Incidence of thrombocytopenia and hypertension and poor compliance were associated with the systemic exposure to sunitinib and its active metabolite. These results suggest that the loss of protein expression of ABCG2 by genetic polymorphism is associated with an increase in the systemic exposure to sunitinib and sunitinib-induced toxicity.
    Drug Metabolism and Pharmacokinetics 06/2012; · 2.07 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: 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. 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. 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 (AUC(0-12)). Neither the concentration at the trough time point nor AUC(0-12) 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). 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.
    European Journal of Clinical Pharmacology 03/2012; 68(3):259-66. · 2.74 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Erlotinib is orally active and selectively inhibits the tyrosine kinase activity of the epidermal growth factor receptor. The pleural space penetration and exposure of erlotinib is poorly understood. Thus, we investigated the pharmacokinetics (PK) of erlotinib and its active metabolite OSI-420 in non-small-cell lung cancer (NSCLC) of malignant pleural effusion (MPE). We analyzed the PK of erlotinib and OSI-420 on days 1 and 8 after beginning erlotinib therapy in 9 patients with MPE. Their concentrations were determined by high-performance liquid chromatography with ultraviolet detection. Blood samples were obtained five times per day: before administration, and 2, 4, 8, and 24 hours after administration. Pleural effusions were obtained once per day, 2 hours after administration on day 1, and before administration on day 8. The exceptions were cases 2 and 4, which had pleural effusions obtained just before drug administration, and 2, 4, 8, and 24 hours after administration. The mean percentage of penetration from plasma to pleural effusion for erlotinib was 18% on day 1 and 112% on day 8, while these values for OSI-420 were 9.5% on day 1 and 131% on day 8. The area under the drug concentration-time curve of pleural fluid for erlotinib was 28,406 ng-hr/mL for case 2 and 45,906 ng-hr/mL for case 4. There seems to be a significant accumulation of both erlotinib and OSI-420 in MPE with repeated dosing. Although larger studies will be necessary to determine the true impact of erlotinib MPE accumulation on plasma PK and safety, erlotinib can be administered safely to patients with MPE with respect to efficacy and side effects.
    Clinical Lung Cancer 07/2011; 12(5):307-12. · 2.04 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Recent reports indicate that refractory central nervous system (CNS) metastases of non-small cell lung cancer (NSCLC) are improved by high-dose gefitinib or erlotinib administration. We describe a Japanese woman with NSCLC and CNS metastases who was resistant to 75 mg daily erlotinib, but the metastases were improved by 150 mg daily erlotinib. We investigated the plasma and CSF concentrations of erlotinib at each dose as well as the correlation between the plasma and CSF concentrations of erlotinib. Including this patient, we administered 150 mg erlotinib daily to nine NSCLC patients with CNS metastases and measured the plasma and CSF concentrations just before administration on day 8. The concentrations were determined using high-performance liquid chromatography with ultraviolet detection. The plasma and CSF concentrations of erlotinib at a dose of 75 mg were 433 and 14 nM, respectively. The plasma and CSF concentrations of erlotinib at a dose of 150 mg were increased to 1,117 and 44 nM, respectively. The mean ± standard deviation of CSF concentrations and penetration rates were 106 ± 59 nM and 4.5 ± 1.5%, respectively. There was a good correlation (R(2) = 0.84) between plasma and CSF concentrations (P = 0.0005). This study indicates that CSF concentrations of erlotinib depend on its plasma concentration. As seen in this patient, high CSF concentrations of erlotinib can be achieved by high-dose administration, and this finding suggests the efficacy of high-dose administration, especially to refractory CNS metastases of NSCLC patients.
    Cancer Chemotherapy and Pharmacology 06/2011; 68(4):1089-92. · 2.80 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Although there have been several reports in which central nervous system (CNS) metastases of non-small cell lung cancer (NSCLC) were improved by erlotinib, cerebrospinal fluid (CSF) penetration of erlotinib in such patients has not been reported. We investigated CSF concentrations of erlotinib and its active metabolite OSI-420. We administered 150 mg erlotinib daily to four patients with NSCLC who had CNS metastases, and we investigated plasma pharmacokinetics of erlotinib and OSI-420 on days 1 and 8. In addition, we measured the concentrations of erlotinib and OSI-420 in CSF just before administration of erlotinib on day 8. In all cases except for one case, plasma pharmacokinetics data on day 8 were similar to those previously reported. The mean +/- SD CSF concentrations of erlotinib and OSI-420 were 54 +/- 30 ng/ml and 10.8 +/- 8.2 ng/ml, respectively. The mean +/- SD CSF penetration rates of erlotinib and OSI-420 were 5.1% +/- 1.9% and 5.8% +/- 3.6%, respectively. CSF concentrations of erlotinib exceeded median inhibitory concentration (IC50) of erlotinib in intact tumor cells with wild-type epidermal growth factor receptor gene. The CSF penetrations of erlotinib and OSI-420 in patients with NSCLC who had CNS metastases were approximately 5.1% and 5.8%, respectively. This indicates that erlotinib can become a treatment option for CNS metastases of NSCLC.
    Journal of thoracic oncology: official publication of the International Association for the Study of Lung Cancer 07/2010; 5(7):950-5. · 4.55 Impact Factor
  • Journal of thoracic oncology: official publication of the International Association for the Study of Lung Cancer 06/2010; 5(6):924-5. · 4.55 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Introduction: Although erlotinib, an orally active and selective tyrosine kinase inhibitor of epidermal growth factor receptor, is mainly metabolized in the liver, its effectiveness and safety for patients with chronic renal failure (CRF) undergoing hemodialysis (HD) has not been reported. Thus, we investigated the pharmacokinetics (PK) of erlotinib and its active metabolite OSI-420 in such patients with nonsmall cell lung cancer (NSCLC). Method: We administered 150 mg erlotinib daily to three patients with NSCLC and CRF undergoing HD (HD group) and five patients with NSCLC and normal organ function (control group) and analyzed the PK of erlotinib and OSI-420. In the HD group, PK analyses were performed on day 1 (off HD), day 8 (off HD), and day 9 (on HD) after starting administration of erlotinib, and in the control group, they were performed on day 1 and day 8. Results: In the HD group, there were little differences in the PK data between day 8 and day 9. The PK data on day 1 and day 8 of the HD group were also similar to those of the control group. There were no serious adverse events in any cases, and one of the HD patients achieved partial response. Conclusion: Erlotinib was hardly affected by renal function and HD, which confirms the effectiveness and safety of erlotinib treatment in patients with NSCLC and CRF undergoing HD. Erlotinib can become one treatment option for such patients.
    Journal of Thoracic Oncology 04/2010; 5(5):601-605. · 4.47 Impact Factor
  • Source
    Annals of Oncology 03/2010; 21(6):1382-3. · 7.38 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Recently, 2 small molecule kinase inhibitors (TKIs), targeting epidermal growth factor receptor (EGFR), have proven effective in the treatment of non-small cell lung cancer. However, it is unknown whether the EGFR double activating mutation of L858R in exon 21 and the in-frame deletion in exon 19 is a predictor of the effectiveness of EGFR-TKIs. We report for the first time a case of non-small cell lung cancer with central nervous system metastases harboring a rare EGFR double activating mutation who showed a good clinical response to erlotinib, regardless of his poor performance status, as swallowing is not possible. Therefore, we suggest that erlotinib may become a therapeutic choice in cases of central nervous system metastases even with poor performance status.
    Case Reports in Oncology 01/2010; 3(2):98-105.
  • [Show abstract] [Hide abstract]
    ABSTRACT: We describe the longitudinal follow-up of calcineurin activity and its clinical relevance in 4 de novo living-donor kidney transplant recipients treated with cyclosporine (n=1) or tacrolimus (n=3). The calcineurin activity in peripheral blood mononuclear cells was measured in combination with therapeutic drug monitoring during hospitalization. Serial blood samplings were performed after the oral administration of each drug to evaluate the temporal pharmacokinetic and pharmacodynamic profiles. Significant changes in enzyme activity were evaluated in relation to clinical outcomes. A nadir of calcineurin activity occurred at the maximum blood drug concentration within 4 h post-dose in most cases. Unlike cyclosporine, tacrolimus partially suppressed calcineurin activity throughout the dosing interval compared to the pre-dose level (cyclosporine, 62-67% inhibition; tacrolimus, 13-35% inhibition). Notably, calcineurin activity rapidly increased a few days before the onset of acute rejection in 2 patients, 1 receiving cyclosporine and 1 receiving tacrolimus, despite the achievement of therapeutic trough blood concentrations. These preliminary findings indicate that therapeutic monitoring of calcineurin activity in addition to the measurement of blood drug concentrations may be helpful to evaluate the pharmacodynamic effects of cyclosporine and tacrolimus early after renal transplantation.
    Drug Metabolism and Pharmacokinetics 01/2010; 25(5):411-7. · 2.07 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Tacrolimus is widely used to prevent acute rejection after transplantation, but achieving therapeutic blood concentrations of tacrolimus is often difficult because of large pharmacokinetic variability. In this study, the applicability of the Bayesian method to individualize tacrolimus dose was prospectively examined. Twenty adult recipients (Bayesian group) and another 20 adult patients (control group), all of whom underwent living-donor liver transplantation, were enrolled in this study. In the Bayesian group, the dose of tacrolimus during the first 3 and 4 weeks after surgery was adjusted with the Bayesian method using a population pharmacokinetic model, targeting a trough level of 5 to 12 ng/mL. The interindividual variability in tacrolimus concentrations was significantly reduced in the Bayesian group compared with the control group (average percentage coefficient of variation for all occasions, 32% vs 44% and 31% vs 39% in the first 3 and 4 weeks, respectively). In addition, more patients achieved the target concentrations in the Bayesian group than in the control group (average for all occasions, 85% vs 59% and 83% vs 70% in the first 3 and 4 weeks, respectively). These findings suggest that the Bayesian method can be used to calculate maintenance doses of tacrolimus in adult patients early after living-donor liver transplantation.
    The Journal of Clinical Pharmacology 08/2009; 49(7):789-97. · 2.84 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The potential influence of the multidrug resistance 1 (MDR1) gene and the cytochrome P450 (CYP) genes, CYP3A4 and CYP3A5, on the oral clearance (CL/F) of tacrolimus in adult living-donor liver transplant patients was examined. Furthermore, the development of renal dysfunction was analyzed in relation to the CYP3A5 genotype. Sixty de novo adult liver transplant patients receiving tacrolimus were enrolled in this study. The effects of various covariates (including intestinal and hepatic mRNA levels of MDR1 and CYP3A4, measured in each tissue taken at the time of transplantation, and the CYP3A5*3 polymorphism) on CL/F during the first 50 days after surgery were investigated with the nonlinear mixed-effects modeling program. CL/F increased linearly until postoperative day 14, and thereafter reached a steady state. The initial CL/F immediately after liver transplantation was significantly affected by the intestinal MDR1 mRNA level (P<0.005). Furthermore, patients carrying the CYP3A5*1 allele in the native intestine, but not in the graft liver, showed a 1.47 times higher (95% confidence interval, 1.17-1.77 times, P<0.005) recovery of CL/F with time than patients having the intestinal CYP3A5*3/*3 genotype. The cumulative incidence of renal dysfunction within 1 year after transplantation, evaluated by the Kaplan-Meier method, was significantly associated with the recipient's but not donor's CYP3A5 genotype (*1/*1 and *1/*3 vs. *3/*3: recipient, 17 vs. 46%, P<0.05; donor, 35 vs. 38%, P=0.81). These findings suggest that the CYP3A5*1 genotype as well as the MDR1 mRNA level in enterocytes contributes to interindividual variation in the CL/F of tacrolimus in adult recipients early after living-donor liver transplantation. Furthermore, CYP3A5 in the kidney may play a protective role in the development of tacrolimus-related nephrotoxicity.
    Pharmacogenetics and Genomics 06/2008; 18(5):413-23. · 3.61 Impact Factor
  • Source
    Masahide Fukudo
    [Show abstract] [Hide abstract]
    ABSTRACT: The calcineurin inhibitors cyclosporine and tacrolimus are widely used to prevent allograft rejection after transplantation. Since these drugs have narrow therapeutic windows and show considerable pharmacokinetic variability, therapeutic drug monitoring (TDM) is essential to avoid adverse effects such as nephrotoxicity while maximizing immunosuppressive efficacy. On the other hand, some patients experience acute rejection episodes or postoperative complications despite achieving therapeutic blood drug levels. Therefore, pharmacokinetic and pharmacodynamic factors by which to establish individualized dosage adjustment for these drugs should be identified. Recently, it was recognized that pharmacogenomics has the potential to facilitate personalized medicine by translating knowledge of human genome variability into rational therapeutics. In this paper, we review the population pharmacokinetic and pharmacogenomic analysis of tacrolimus, focusing on an efflux transporter P-glycoprotein (multidrug resistance 1 [MDR1/ABCB1]) and drug-metabolizing enzymes cytochrome P450 (CYP) 3A4 and 3A5, and describe Bayesian forecasting to individualize the tacrolimus dose in de novo living-donor liver transplant recipients. Furthermore, the pharmacodynamic properties of tacrolimus and cyclosporine, which were evaluated by measuring calcineurin phosphatase activity in peripheral blood mononuclear cells, are reviewed in relation to an optimal monitoring strategy as well as a rational dosage regimen for these drugs.
    Yakugaku zasshi journal of the Pharmaceutical Society of Japan 08/2007; 127(7):1081-9. · 0.46 Impact Factor