Pharmacokinetics in stable kidney transplant recipients after conversion from twice-daily to once-daily tacrolimus formulations. Ther Drug Monit. 2012;34:46-52. [PMID: 22249344 DOI: 10.1097/ftd.0b013e318244a7fd]

Tacrolimus Formulation, Exposure Variability, and Outcomes in Kidney Transplant Recipients

INTRODUCTION

Few studies have compared within-patient variability measures of tacrolimus trough levels by formulation and assessed within-patient variability on outcomes of kidney transplant recipients.

RESEARCH QUESTIONS

(1) To compare within-patient variability of trough levels when converting from twice-daily to once-daily tacrolimus using standard deviation, coefficient of variation, and intrapatient variability percent. (2) To use the 3 measures of variability to examine the relationship between tacrolimus once-daily within-patient variability and total graft failure (i.e., return to chronic dialysis, pre-emptive retransplant, death with graft function).

DESIGN

In this observational cohort study, within-patient variability of trough levels pre- and post-conversion from twice-daily to once-daily tacrolimus were compared using Wilcoxon matched-pairs signed-rank test. Graft outcomes were analyzed using Kaplan-Meier curves and multivariable Cox proportional hazards models.

RESULTS

In 463 patients, within-patient variability differences pre- and post-conversion of median standard deviation, coefficient of variation, and intrapatient variability percent were -0.16 (P = 0.09), -0.01 (P = 0.52), and -1.41 (P = 0.32), respectively. Post-conversion, every 1 unit increase in within-patient variability standard deviation and intrapatient variability percent and every 0.1 unit increase in the coefficient of variation was associated with an increased hazard ratio [1.19 (P = 0.004), 1.02 (P = 0.030), 1.13 (P = 0.001), respectively] of total graft failure. Post-conversion, within-patient variability above cohort medians using standard deviation and coefficient of variation had a significantly higher risk of total graft failure.

DISCUSSION

Under a program-wide conversion, no significant difference was observed in within-patient variability post-conversion from twice-daily to once-daily tacrolimus using the three measures of variability. High within-patient variability was associated with adverse transplant outcomes post-conversion.

Tacrolimus dose adjustment is not necessary in dose to dose conversion from a twice daily to a prolonged release once daily dose form

Twice daily TAC (BID TAC) and prolonged released once daily dose tacrolimus (OD TAC) have different pharmacokinetic (PK) profiles in kidney transplant (KT) recipients. Precise dose adjustment recommendations when converting from BID TAC to OD TAC remain inconclusive. A single center, PK study was conducted in stable KT recipients taking constant doses of TAC, mycophenolic acid, and prednisolone. The area under the concentration-time curve (AUC) 0-24 and C_trough were measured before and 4 weeks after 1:1 conversion from BID TAC to OD TAC without subsequent dose adjustment. A 90% confidence interval (CI) of geometric mean ratio (GMR) of OD TAC/BID TAC within the range of 0.9-1.11 was utilized to indicate equivalence of the narrow therapeutic index drugs. The roles of CYP3A5 genotypic polymorphism on PK parameters were also assessed. There were 20 patients with median time since transplantation of 18 months. The mean of CKD-EPI eGFR was 60.7 ± 16.43 mL/min/1.73 m². The median total daily TAC dose of 0.058 mg/kg/day. The geometric means (%CV) of AUC_0-24 of OD and BID TAC were 205.16 (36.4%) and 210.3 (32.5%) ng/mL × h, respectively, with a GMR of 0.98 (90%CI 0.91-1.04). The geometric means (%CV) of C_trough of OD TAC and BID TAC were 5.43 (33.1%) and 6.09 (34.6%) ng/mL, respectively. The GMR of C_trough was 0.89 (90%CI 0.82-0.98), which was below 0.9. The newly calculated target C_trough level of OD TAC was 4.8-6.2 ng/mL. The best abbreviated AUC_0-24 was AUC = 0.97(C0) + 5.79(C6) + 18.97(C12) - 4.26. The GMR AUC_0-24 was within the range of 0.9-1.11 irrespective of CYP3A5 genotypic polymorphism while the GMR of C_trough was below 0.9 only in the CYP3A5 expressor patients. The 1:1 conversion from BID TAC to OD TAC without subsequent dose adjustment provided similar AUC_0-24 regardless of CYP3A5 genotypic polymorphism. However, the C_trough was lower in the CYP3A5 expressor group. Therefore, it is not necessary to routinely increase the OD TAC dose after conversion.Trial registration: Thai Clinical Trials Registry (TCTR20210715002).

A randomized crossover study comparing different tacrolimus formulations to reduce intrapatient variability in tacrolimus exposure in kidney transplant recipients

A high intrapatient variability (IPV) in tacrolimus exposure is a risk factor for poor long‐term outcomes after kidney transplantation. The main objective of this trial was to investigate whether tacrolimus IPV decreases after switching patients from immediate‐release (IR)‐tacrolimus to either extended‐release (ER)‐tacrolimus or LifeCyclePharma (LCP)‐tacrolimus. In this randomized, prospective, open‐label, cross‐over trial, adult kidney transplant recipients on a stable immunosuppressive regimen, including IR‐tacrolimus, were randomized for conversion to ER‐tacrolimus or LCP‐tacrolimus, and for the order in which IR‐tacrolimus and the once‐daily formulations were taken. Patients were followed 6 months for each formulation, with monthly tacrolimus predose concentration assessments to calculate the IPV. The IPV was defined as the coefficient of variation (%) of dose corrected predose concentrations. Ninety‐two patients were included for analysis of the primary outcome. No significant differences between the IPV of IR‐tacrolimus (16.6%) and the combined once‐daily formulations (18.3%) were observed (% difference +1.7%, 95% confidence interval [CI] −1.1% to ‒4.5%, p = 0.24). The IPV of LCP‐tacrolimus (20.1%) was not significantly different from the IPV of ER‐tacrolimus (16.5%, % difference +3.6%, 95% CI −0.1% to 7.3%, p = 0.06). In conclusion, the IPV did not decrease after switching from IR‐tacrolimus to either ER‐tacrolimus or LCP‐tacrolimus. These results provide no arguments to switch kidney transplant recipients from twice‐daily (IR) tacrolimus formulations to once‐daily (modified‐release) tacrolimus formulations when the aim is to lower the IPV.

Differential Effect of a Continental Breakfast on Tacrolimus Formulations With Different Release Characteristics

Food reduces tacrolimus bioavailability after immediate-release tacrolimus (IR-Tac) and after a new prolonged-release tacrolimus formulation (PR-Tac), when using a high-fat breakfast, but the effects of a continental breakfast on PR-Tac are unknown. In an open-label, 4-phase, randomized, 2-sequence, crossover pharmacokinetic trial, 36 healthy volunteers (18 females) received single 5-mg tacrolimus doses as PR-Tac and as IR-Tac fasted or with a standardized continental breakfast. Tacrolimus pharmacokinetics were analyzed using noncompartmental methods and mixed-model analysis of variance. The continental breakfast significantly decreased average tacrolimus exposure (area under the plasma concentration-time curve) with both preparations (IR-Tac, 67%; 90% confidence interval [CI], 59%-75%; P < .01; and PR-Tac, 79%; 90%CI, 70%-89%; P < .01) with a nonsignificant difference between both preparations (P = .10). The maximum concentration (C_max ) and the time to maximum concentration (t_max ) were significantly affected only after IR-Tac (C_max IR-Tac, 39%; 90%CI, 34%-45%; P < .01; and PR-Tac, 87%; 90%CI, 76%-101%; P = .11; t_max IR-Tac, 212%, 90%CI, 179%-252%; P < .01; and PR-Tac, 101%; 90%CI, 86%-120%; P = .89), which was significantly different between both preparations (P < .01). Considering switching from IR-Tac to PR-Tac, predicted dose requirements differed according to the timing of drug intake in relation to food. In conclusion, a continental breakfast decreased average tacrolimus exposure of both preparations to a similar extent. C_max and t_max were affected only after IR-Tac. The effect of a standardized continental breakfast on PR-Tac was considerably smaller than previously reported effects of a high-fat breakfast on PR-Tac.

Trough Level and Tacrolimus Variability of Early Converted Once-Daily Tacrolimus: 1-Year Follow-up Study

INTRODUCTION

Long-term transplant outcomes are considered a crucial point for kidney transplantation. Follow-up studies in patients receiving early conversion to once-daily tacrolimus (TAC-OD) are still limited. We aimed to investigate tacrolimus trough level (C_min), intrapatient variability of tacrolimus dose-normalized C_min (TAC-C_min/D), along with other outcomes between twice-daily tacrolimus (TAC-BID) and early converted TAC-OD.

MATERIAL AND METHODS

This study was a single center, retrospective, cohort study. All new kidney transplant patients who received tacrolimus and presented an estimated glomerular filtration rate of more than 45 mL/min/1.73 m² on the day of hospital discharge were included. Studied patients were divided into the standard TAC-BID and patients who were converted from TAC-BID to TAC-OD on the day of hospital discharge. We followed patients for 1 year after transplantation.

RESULTS

At the first follow-up visit, C_min of TAC-OD was significantly lower than that of TAC-BID. However, C_min and estimated glomerular filtration rate were comparable between TAC-BID and TAC-OD throughout 1-year follow-up. TAC-OD also provided a lower intrapatient variability of TAC-C_min/D compared with TAC-BID when observed after 6 months post transplantation (17.40% and 23.27% for TAC-OD and TAC-BID, respectively; P = .13). The renal function, as well as other adverse outcomes, was similar between 2 formulations.

DISCUSSION

TAC-OD provided a similar C_min with comparable renal function compared with TAC-BID during 1-year follow-up. In addition, TAC-OD is likely to have a benefit of a lower intrapatient variability of tacrolimus.

CONCLUSION

Early conversion from TAC-BID to TAC-OD with 1:1 ratio can be used with close long-term monitoring.

Dosing Requirements of Extended-Release Tacrolimus (Astagraf XL) in African American Kidney Transplant Recipients Converted from Immediate-Release Tacrolimus (AAAKTRS)

BACKGROUND

The formal recommendation for converting twice-daily tacrolimus immediate release (IR) to once-daily tacrolimus extended release (ER) is a 1:1 dose conversion. However, more recent clinical analysis has shown that this may not be true; some patients may require a higher dose. In addition, de novo dosing tacrolimus ER has revealed that African Americans require approximately 20%-30% higher doses than Caucasians to achieve similar levels. As a result, this study sought to identify the appropriate dose conversion in the African American kidney transplant population, a population at high risk of rejection.

METHODS

This was a single-center, prospective, open-label study comparing the difference in dose-normalized trough and total daily dose necessary to reach steady-state therapeutic goal, after conversion from tacrolimus IR to tacrolimus ER, in 25 African American kidney transplant recipients.

RESULTS

After conversion to tacrolimus ER, there was a significant decrease in dose-normalized trough (C0) (0.44 versus 0.59, P = 0.03). Statistically significant differences were seen in both total daily and weight-based doses, when reported as actual values (15 versus 10 mg and 0.16 versus 0.11 mg/kg, respectively), as well as when standardized to achieve a target tacrolimus C0 of 8 ng/mL (18.1 versus 13.6 mg and 0.17 versus 0.15 mg/kg, respectively). The median standardized dose conversion required was 1.3 [1.0, 1.4], for the overall population. There were no instances of biopsy-proven acute rejection, allograft loss, or study drug discontinuation.

CONCLUSIONS

This single-center, open-label conversion study demonstrated that there was a statistically and clinically significant decrease in dose-normalized trough after conversion from tacrolimus IR to tacrolimus ER in an African American kidney transplant population and that a 1:1 dose conversion is unlikely to meet therapeutic goals.

Long-Term Kidney Transplant Outcomes: Role of Prolonged-Release Tacrolimus

Tacrolimus has significantly improved outcomes for kidney transplant patients and remains the cornerstone of immunosuppressive therapy. While improvements in short-term outcomes in transplantation have been achieved in recent years, maintaining long-term graft survival remains a challenge in kidney transplantation. Minimizing risk factors for poor long-term kidney graft function and survival, and modifying tacrolimus regimens in the early and maintenance phases post-transplantation are essential to maintain long-term kidney transplant outcomes. Tacrolimus has a narrow therapeutic window, resulting in a tightly defined range of optimal drug exposure. Underimmunosuppression is associated with long-term risks, such as the development of donor-specific antibodies and antibody-mediated rejection, with a high possibility of a decline in kidney function and progression to graft failure. Conversely, prolonged overimmunosuppression carries a risk of drug-related adverse events. This review provides an overview of the differences in the formulation, delivery, and pharmacokinetic profiles between immediate- and prolonged-release tacrolimus and evaluates the effect of prolonged-release tacrolimus on the risk factors for poor outcomes in kidney transplantation. Recent evidence is used to provide guidance on target tacrolimus trough levels in the early and maintenance phases post-transplantation, with a view to improving long-term kidney graft function.

A non-randomized trial of conversion from ciclosporin and tacrolimus to tacrolimus MR4 in stable long-term kidney transplant recipients: Graft function and influences of ABCB1 genotypes

TRIAL REGISTRATION

PEP Study: Ethics committee N° 393/2004, EudraCT 2004-004209-98. PEP-X Study: Ethics committee amendment application N° 154/01/2008. ClinicalTrials.gov NCT03751332.

Population pharmacokinetics of immediate- and prolonged-release tacrolimus formulations in liver, kidney and heart transplant recipients

Aims

Develop a population pharmacokinetics model of tacrolimus in organ transplant recipients receiving twice‐daily, immediate‐release (IR‐T; Prograf) and/or once‐daily, prolonged‐release (PR‐T; Advagraf or Astagraf XL) tacrolimus.

Methods

Tacrolimus concentration–time profiles were analysed from 8 Phase II studies in adult and paediatric liver, kidney and heart transplant patients receiving IR‐T and/or PR‐T. A tacrolimus population pharmacokinetic model, including identification of significant covariates, was developed using NONMEM.

Results

Overall, 23,176 tacrolimus concentration records were obtained from 408 patients. A 2‐compartment model with first‐order absorption and elimination described the concentration–time profiles. Tacrolimus absorption rate was 50% slower with PR‐T vs IR‐T. Tacrolimus apparent oral clearance was 44.3 L/h in Whites and 59% higher in Asians. Tacrolimus central volume of distribution was 108 L in males and 55% lower in females; trough concentrations were similar between formulations. Tacrolimus relative bioavailability was similar between formulations (geometric mean ratio PR‐T:IR‐T 95%, 90% confidence intervals: 89%, 101%). Asians had 83% and 51% higher relative bioavailability than Whites and Blacks, respectively, for IR‐T and PR‐T. Whites had 49% and 77% higher relative bioavailability than Blacks for PR‐T and IR‐T, respectively. Blacks had 52% lower relative bioavailability than Whites and Asians for IR‐T and PR‐T. Type of organ transplanted and patient population (adult/paediatric) did not have a significant effect on tacrolimus pharmacokinetics.

Conclusions

This population pharmacokinetic model described data from transplant recipients who received IR‐T and/or PR‐T. Tacrolimus trough concentrations and relative bioavailability were similar between formulations, supporting 1 mg:1 mg conversion from Prograf to Advagraf/Astagraf XL in clinical practice.

Real-World Study of Once-Daily, Extended-Release Tacrolimus Versus Twice-Daily, Immediate-Release Tacrolimus in Kidney Transplantation: Clinical Outcomes and Healthcare Resource Utilization

INTRODUCTION

Real-world data with extended-release tacrolimus (ER-T) are lacking in the USA. This study examined clinical outcomes and healthcare resource utilization in kidney transplant patients receiving ER-T in clinical practice.

METHODS

This was a retrospective, single-center analysis (February-June 2016) using data from Northwestern University's Enterprise Data Warehouse. Adult patients receiving a kidney transplant in the preceding 4 years, treated de novo or converted to ER-T from immediate-release tacrolimus (IR-T) within 10 days post-transplantation, and maintained on ER-T (at least 3 months) were included. Patients were matched for demographic and clinical characteristics with IR-T-treated control patients. Endpoints included clinical outcomes and healthcare resource utilization up to 1 year post-transplantation.

RESULTS

A total of 19 ER-T-treated patients were matched with 55 IR-T-treated patients. No ER-T-treated patients experienced biopsy-confirmed acute rejection (BCAR) or graft failure versus 3 (5.5%) and 3 (5.5%) IR-T-treated patients, respectively. Mean estimated glomerular filtration rate (eGFR), the number of all-cause outpatient visits, readmissions, and all-cause hospitalization days were comparable between groups. Tacrolimus trough levels, days to target level (6-10 ng/mL), and number of required dose adjustments were also similar.

CONCLUSION

Real-world clinical outcomes and healthcare resource utilization were similar with ER-T and IR-T. Larger studies will need to investigate the trend toward fewer BCAR events, and increased graft survival with ER-T.

FUNDING

Astellas Pharma Global Development, Inc. Plain language summary available for this article.

Comparative pharmacokinetics of tacrolimus in stable pediatric allograft recipients converted from immediate-release tacrolimus to prolonged-release tacrolimus formulation

This study was a Phase II, open-label, multicenter, single-arm, cross-over study comparing the pharmacokinetics (PK) of tacrolimus in stable pediatric kidney, liver, or heart allograft recipients converted from immediate-release tacrolimus (IR-T) to prolonged-release tacrolimus (PR-T). In Days -30 to -1 of screening period, patients received their IR-T-based regimen; during Days 1-7, patients received study IR-T (same dose as screening). On Day 7, the first 24-hours PK profile was taken; patients were then converted to PR-T (1 mg:1 mg), with a second 24-hours PK profile taken on Day 14. The primary end-point was tacrolimus area under the blood concentration-time curve over 24 hours (AUC₂₄ ); secondary end-points were maximum concentration C_max and concentration at 24 hours C₂₄ . The predefined similarity interval for confidence intervals (CIs) of least squares mean (LSM) ratios was 80%-125%. The PK analysis set comprised 74 pediatric transplant recipients (kidney, n = 45; liver, n = 28; heart, n = 1). PR-T:IR-T LSM ratio (90% CI) was similar overall for AUC₂₄ , _max , and C₂₄ , and for kidney and liver recipients for AUC₂₄ (LSM ratio, kidney 91.8%; liver 104.1%) and C₂₄ (kidney 90.5%; liver 89.9%). Linear relationship was similar between AUC₂₄ and C₂₄ , and between PR-T and IR-T (rho 0.89 and 0.84, respectively), suggesting that stable pediatric transplant recipients can be converted from IR-T to PR-T at the same total daily dose, using the same therapeutic drug monitoring method.

Comparative pharmacokinetics of tacrolimus in de novo pediatric transplant recipients randomized to receive immediate- or prolonged-release tacrolimus

Phase 2, parallel-group, multicenter, open-label, 4-week study, comparing PK of PR-T vs IR-T in de novo pediatric patients undergoing primary kidney, liver, or heart transplantation. Patients randomized 1:1 to receive once daily, PR-T-, or twice-daily, IR-T-based regimens; dose adjustments permitted after Day 1. Twenty-four-hour PK profiles collected on Days 1, 7, and 28. Primary endpoint: tacrolimus AUC₂₄ . Secondary end points included tacrolimus C₂₄ and C_max . Endpoints compared between PR-T and IR-T on Days 1, 7, and 28. Predefined similarity interval for CIs of LSM ratios: 80%-125%. PK analysis set comprised 33 patients (PR-T, n = 15; IR-T, n = 18). Overall, AUC₂₄ and C_max were lower on Day 1 vs 7 and 28. Geometric LSM ratios of PR-T:IR-T on Days 1, 7, and 28 were 66.3%, 92.5%, 99.9%, respectively, for AUC₂₄ ; 66.3%, 82.2%, 90.9% for C₂₄ ; and 77.3%, 120.3%, 92.2% for C_max . AUC₂₄ 90% CI within predefined similarity interval on Day 28; other 90% CIs fell outside. Linear relationship was similar between AUC₂₄ and C₂₄ , and between tacrolimus formulations, suggesting that the same therapeutic drug monitoring method can be used with both formulations in de novo pediatric allograft recipients.

Conversion from Twice-Daily Prograf® to Once-Daily Advagraf® in Multi-ethnic Asian Adult Renal Transplant Recipients With or Without Concomitant Use of Diltiazem: Impact of CYP3A5 and MDR1 Genetic Polymorphisms on Tacrolimus Exposure

BACKGROUND AND OBJECTIVES

Tacrolimus is the mainstay of immunosuppression in renal transplantation. Given that once-daily administration improves patient compliance, 1:1 dose conversion from twice-daily Prograf^® to once-daily Advagraf^® is recommended. Although cytochrome P450 (CYP) 3A5 and multi-drug resistance 1 (MDR1) polymorphisms influence tacrolimus concentrations, it is unknown if these impact on conversion. This study investigated the change in the pharmacokinetics of tacrolimus after conversion from Prograf^® to Advagraf^® and examined the impact of CYP3A5 and MDR1 C3435T polymorphisms on those pharmacokinetics.

METHODS

A prospective open-label pharmacokinetic study of 1:1 conversion from Prograf^® to Advagraf^® with or without diltiazem was conducted on 26 stable renal transplant recipients. Blood samples were collected over 24 h during each phase, tacrolimus concentrations were assayed, and noncompartmental pharmacokinetic analysis was performed. All participants were genotyped for CYP3A5*3 and MDR1 C3435T.

RESULTS

After conversion, without diltiazem, the area under the concentration-time curve at steady state from 0 to 24 h after dose administration (AUC_{ss, 0-24}) was significantly reduced [median 224 (range 172-366) vs. 184 (104-347) ng·h/mL, p = 0.006, n = 26]. A decrease in tacrolimus exposure (median 21%) was only evident among CYP3A5 expressors [227 (172-366) vs. 180 (104-347) ng·h/mL, p = 0.014, n = 18], not among non-expressors [215 (197-290) vs. 217 (129-281) ng·h/mL, p = 0.263, n = 8]. In contrast, among CYP3A5 expressors receiving diltiazem, AUC_{ss, 0-24} did not change significantly upon conversion [229 (170-296) vs. 221 (123-342) ng·h/mL, p = 0.575, n = 10]. An independent effect was not evident for MDR1 C3435T polymorphism.

CONCLUSION

The high prevalence of CYP3A5 polymorphism among Asians may lead to a significant reduction in tacrolimus exposure with 1:1 dose conversion of Prograf^® to Advagraf^®. These results advocate for CYP3A5 determination prior to conversion, and suggest that 1:1.25 conversion should be used for CYP3A5 expressors and 1:1 conversion for other patients.

Tacrolimus intra-patient variability is not associated with chronic active antibody mediated rejection

Background

Chronic active antibody mediated rejection (c-aABMR) is a major cause of long-term kidney allograft loss. It is hypothesized that frequent sub-therapeutic exposure to immunosuppressive drugs, in particular tacrolimus (Tac), is a risk factor for the development of c-aABMR. The intra-patient variability (IPV) in Tac exposure may serve as a substitute biomarker for underexposure and/or non-adherence. In this study, the association between Tac IPV and the development of c-aABMR was investigated.

Methods

We retrospectively included 59 patients diagnosed with c-aABMR and compared them to 189 control patients matched for age, year of transplantation and type of kidney donor. The Tac IPV was calculated from pre-dose tacrolimus concentrations measured over a 3 year period preceding the diagnosis of c-aABMR. The mean Tac predose concentrations (C₀), Tac IPV, renal allograft function and graft survival were compared between the groups.

Results

Tac IPV was 24.4% for the cases versus 23.6% for the controls (p = 0.47). The mean Tac C₀ was comparable for the cases (5.8 ng/mL) and control patients (6.1 ng/mL, p = 0.08). Only in the c-aABMR group a significant decline in both mean Tac C₀ and allograft function over the timespan of 3 years was observed (p = 0.03 and p<0.001). Additionally, in the group of c-aABMR patients a high IPV was associated with inferior graft survival (p = 0.03).

Conclusions

A high Tac IPV per se does not predispose to the development of c-aABMR but is associated with inferior graft survival once c-aABMR is diagnosed.

High tacrolimus intra-patient variability is associated with graft rejection, and de novo donor-specific antibodies occurrence after liver transplantation

AIM

To investigate the role of tacrolimus intra-patient variability (IPV) in adult liver-transplant recipients.

METHODS

We retrospectively assessed tacrolimus variability in a cohort of liver-transplant recipients and analyzed its effect on the occurrence of graft rejection and de novo donor-specific antibodies (dnDSAs), as well as graft survival during the first 2 years posttransplantation. Between 02/08 and 06/2015, 116 patients that received tacrolimus plus mycophenolate mofetil (with or without steroids) were included.

RESULTS

Twenty-two patients (18.5%) experienced at least one acute-rejection episode (BPAR). Predictive factors for a BPAR were a tacrolimus IPV of > 35% [OR = 3.07 95%CI (1.14-8.24), P = 0.03] or > 40% [OR = 4.16 (1.38-12.50), P = 0.01), and a tacrolimus trough level of < 5 ng/mL [OR=3.68 (1.3-10.4), P =0.014]. Thirteen patients (11.2%) developed at least one dnDSA during the follow-up. Tacrolimus IPV [coded as a continuous variable: OR = 1.1, 95%CI (1.0-1.12), P = 0.006] of > 35% [OR = 4.83, 95%CI (1.39-16.72), P = 0.01] and > 40% [OR = 9.73, 95%CI (2.65-35.76), P = 0.001] were identified as predictors to detect dnDSAs. IPV did not impact on patient- or graft-survival rates during the follow-up.

CONCLUSION

Tacrolimus-IPV could be a useful tool to identify patients with a greater risk of graft rejection and of developing a de novo DSA after liver transplantation

Longitudinal Pharmacokinetics of Tacrolimus in Elderly Compared With Younger Recipients in the First 6 Months After Renal Transplantation

BACKGROUND

Elderly (Eld) (≥60 years) recipients are receiving renal transplants more frequently. The pharmacokinetics (PK) studies of immunosuppressive drugs in healthy volunteers, rarely, include old patients.

METHODS

We studied 208 12-hour tacrolimus (TAC) PK (0, 20, 40, 60, 90, 120, 180, 240, 360, 480, 600, 720 min) in 44 Eld (65 ± 3 years) and compared the results with 31 younger controls (Ctrl) (35 ± 6 years) recipients, taking oral TAC/mycophenolate sodium (MPS)/prednisone, at 4 different timepoints: PK1 (8 ± 2 days; n = 72), PK2 (31 ± 4 days; n = 61), PK3 (63 ± 6 days; n = 44), and PK4 (185 ± 10 days; n = 31). Tacrolimus PK was measured by ultraperformance liquid chromatography coupled to a mass spectrometer repetition and noncompartmental PKs were analyzed using Phoenix WinNonlin.

RESULTS

Mean TAC dose was lower in the Eld group than in Ctrl ones throughout timepoints either by total daily dose or adjusted (Adj) per body weight. Mean TAC trough level (Cmin), used to adjust daily dose, was not different between the 2 groups in all timepoints. AdjCmax and AdjTAC-area under the curve at dosing interval were both higher in the Eld compared to the Ctrl group in PKs1, 3, and 4. Estimated total body clearance normalized by dose and weight was lower in the Eld group compared with the Ctrl in all PKs and statistically lower at PKs 1 and 3. Similar to younger recipients TAC trough level has also a high correlation (R = 0.76) with area under the curve at dosing interval.

CONCLUSIONS

These data indicate that Eld recipients have a lower TAC clearance and therefore need a lower TAC dose than younger recipients.

Clinical Evaluation of Modified Release and Immediate Release Tacrolimus Formulations

The science of drug delivery has evolved considerably and has led to the development of multiple sustained release formulations. Each of these formulations can present particular challenges in terms of clinical evaluation and necessitate careful study to identify their optimal use in practice. Tacrolimus is an immunosuppressive agent that is widely used in organ transplant recipients. However, it is poorly soluble, has an unpredictable pharmacokinetic profile subject to important genetic polymorphisms and drug-drug interactions, and has a narrow therapeutic index. For these reasons, it represents an agent that could benefit from modified release formulations to overcome these limitations. The objective of this review is to discuss the clinical evaluation of immediate and modified release tacrolimus formulations in renal transplant recipients. Clinical trials from early development of immediate release tacrolimus to formulation-specific post-marketing trials of modified release tacrolimus formulations are reviewed with an emphasis on key elements relating to trial design end endpoint assessment. Particular elements that can be addressed with formulation alterations, such as pharmacokinetics, pharmacogenomics, and toxicity and corresponding clinical evaluations are discussed. In addition, current knowledge gaps in the clinical evaluation of immediate and modified release tacrolimus formulations are discussed to highlight potential avenues for the future development of different tacrolimus formulations with outcomes relevant to the regulators, the transplant community, and to transplant recipients. This review shows that new formulations may alter tacrolimus bioavailability, alleviate certain adverse events while potentially enhancing patient convenience.

Relative bioavailability of single doses of prolonged-release tacrolimus administered as a suspension, orally or via a nasogastric tube, compared with intact capsules: a phase 1 study in healthy participants

OBJECTIVE

Tacrolimus, an immunosuppressant widely used in solid organ transplantation, is available as a prolonged-release capsule for once-daily oral administration. In the immediate postsurgical period, if patients cannot take intact capsules orally, tacrolimus therapy is often initiated as a suspension of the capsule contents, delivered orally or via a nasogastric tube. This study evaluated the relative bioavailability of prolonged-release tacrolimus suspension versus intact capsules in healthy participants.

DESIGN

A phase 1, open-label, single-dose, cross-over study.

SETTING

A single clinical research unit.

PARTICIPANTS

In total, 20 male participants, 18-55 years old, entered and completed the study.

INTERVENTIONS

All participants received nasogastric administration of tacrolimus 10 mg suspension in treatment period 1, with randomisation to oral administration of suspension or intact capsules in periods 2 and 3. Blood concentration-time profile over 144 hours was used to estimate pharmacokinetic parameters.

PRIMARY AND SECONDARY OUTCOME MEASURES

Primary end point: relative bioavailability of prolonged-release intact capsule versus oral or nasogastric administration of prolonged-release tacrolimus suspension (area under the concentration-time curve (AUC) from time 0 to infinity post-tacrolimus dose (AUC_0-∞); AUC measured until the last quantifiable concentration (AUC_0-tz); maximum observed concentration (C_max); time to C_max (T_max)). Tolerability was assessed throughout the study.

RESULTS

Relative bioavailability of prolonged-release tacrolimus suspension administered orally was similar to intact capsules, with a ratio of least-square means for AUC_0-tz and AUC_0-∞ of 1.05 (90% CI 0.96 to 1.14). Bioavailability was lower with suspension administered via a nasogastric tube versus intact capsules (17%; ratio 0.83; CI 0.76 to 0.92). C_max was higher for oral and nasogastric suspension (30% and 28%, respectively), and median T_max was shorter (difference 1.0 and 1.5 hours postdose, respectively) versus intact capsules (2.0 hours). Single 10 mg doses of tacrolimus were well tolerated.

CONCLUSIONS

Compared with intact capsules, the rate of absorption of prolonged-release tacrolimus from suspension was faster, leading to higher peak blood concentrations and shorter time to peak; relative bioavailability was similar with suspension administered orally.

A preliminary study searching for the right dose of tacrolimus in very young (≤4 years) renal transplant patients

OBJECTIVES

The Radboudumc Amalia Children's hospital in the Netherlands has a programme for renal transplantation in children aged ≤4 years. Children receive chronic corticosteroid sparing immunosuppressive therapy that consists of tacrolimus and mycophenolate mofetil. This work aimed to describe the PK of tacrolimus in children ≤4 years with renal transplants.

METHODS

Paediatric renal transplant patients aged ≤4 years were included in this analysis. A PK curve of tacrolimus recorded ≤3 weeks after transplantation has been standard of care in our institution and aided in adjusting the dose in each patient to attain a target AUC_0-12h of 210 μg h/l early after transplantation.

KEY FINDINGS

Eight patients were included. The first two patients received an initial twice-daily regimen and the subsequent six patients a three-times daily regimen. Median dose-corrected AUC_tau was 63 μg h/l. AUC target attainment was 37.5%. Of the remaining patients, two had an AUC very close to (around 10% below) the target.

CONCLUSIONS

Large interindividual variability of tacrolimus was observed and showed suboptimal AUC target attainment. In this population, an even more aggressive approach of higher doses (e.g. 0.4 mg/kg per day) and more early AUC determination should be considered. This should be evaluated prospectively in a larger group of patients.

Pharmacokinetics of prolonged-release tacrolimus and implications for use in solid organ transplant recipients

Prolonged-release tacrolimus was developed as a once-daily formulation with ethylcellulose as the excipient, resulting in slower release and reduction in peak concentration (Cmax ) for a given dose compared with immediate-release tacrolimus, which is administered twice daily. This manuscript reviews pharmacokinetic information on prolonged-release tacrolimus in healthy subjects, in transplant recipients converted from immediate-release tacrolimus, and in de novo kidney and liver transplant recipients. As with the immediate-release formulation, prolonged-release tacrolimus shows a strong correlation between trough concentration (Cmin ) and area under the 24-hour time-concentration curve (AUC24 ), indicating that trough whole blood concentrations provide an accurate measure of drug exposure. We present the pharmacokinetic similarities and differences between the two formulations, so that prescribing physicians will have a better understanding of therapeutic drug monitoring in patients receiving prolonged-release tacrolimus.

Overview of extended release tacrolimus in solid organ transplantation

Tacrolimus (Prograf^©, Astellas Pharma Europe Ltd, Staines, United Kingdom; referred to as tacrolimus-BID) is an immunosuppressive agent to prevent and treat allograft rejection in kidney transplant recipients in combination with mycophenolate mofetil, corticosteroids, with or without basiliximab induction. The drug has also been studied in liver, heart and lung transplant; however, these are currently off-label indications. An extended release tacrolimus formulation (Advagraf^©, Astagraf XL^©) allows for once-daily dosing, with the potential to improve adherence. Extended release tacrolimus has similar absorption, distribution, metabolism and excretion to tacrolimus-BID. Phase I pharmacokinetic trials comparing extended release tacrolimus and tacrolimus-BID have demonstrated a decreased maximum concentration (C_max) and delayed time to maximum concentration (t_max) with the extended release formulation; however, AUC_0-24 was comparable between formulations. Overall extended release tacrolimus has a very similar safety and efficacy profile to tacrolimus-BID. It is not recommended in the use of liver transplant patient’s due to the increased risk of mortality in female recipients. There has been minimal data regarding the use of extended release tacrolimus in heart and lung transplant recipients. With the current data available for all organ groups the extended release tacrolimus should be dosed in a 1:1 fashion, the exception may be the cystic fibrosis population where their initial dose may need to be higher.

Conversion from twice-daily to once-daily tacrolimus does not reduce intrapatient variability in tacrolimus exposure

BACKGROUND

Intrapatient variability (IPV) in tacrolimus exposure is associated with renal allograft failure. The aim of this study was to investigate whether conversion from the twice-daily tacrolimus formulation (Tac-TD) to a once-daily formulation (Tac-OD) leads to a lower IPV in tacrolimus exposure.

METHODS

Two hundred forty-seven stable renal transplant recipients were converted from Tac-TD to Tac-OD (Advagraf) on a 1:1-mg total daily dose basis. After conversion, patients were followed for 12 months and tacrolimus predose whole-blood concentrations (C0), serum creatinine, estimated glomerular filtration rate, and proteinuria were measured. These parameters were compared with those collected at all outpatient visits in the 12-month period (±3 months) before conversion (Tac-TD period). The IPV was calculated based on the dose-adjusted tacrolimus C0.

RESULTS

The Tac-OD formulation provided an excellent graft survival (100%), a low acute rejection rate (0.8%), and good tolerability. Renal function remained stable: estimated glomerular filtration rate 48 (16-90) versus 46 (12-90) mL/min (P = 0.15) before and after conversion, respectively. After conversion to Tac-OD, mean C0 was significantly lower, decreasing from 5.7 ± 1.5 to 5.0 ± 1.5 ng/mL, corresponding to a 12% reduction (P < 0.01). Both drugs had similar IPVs (Tac-TD: 17.3% ± 1.6% versus Tac-OD: 16.4% ± 1.6%, P = 0.31).

CONCLUSIONS

Although conversion from Tac-TD to Tac-OD significantly reduces tacrolimus exposure as measured by C0 and seems safe, it does not reduce IPV in tacrolimus exposure.

Limited sampling strategy for prolonged-release tacrolimus in renal transplant patients by use of the dried blood spot technique

Purpose

The aim of this study was to develop a clinically applicable limited sampling strategy for ambulatory Caucasian kidney transplant patients to estimate area under the curve in a 24-h period (AUC_0–24) of prolonged-release tacrolimus.

Methods

Twenty six kidney recipients, at least 6 months after transplantation, receiving prolonged-release tacrolimus, were enrolled. In each patient, seven blood samples were collected during a period of 24 h by use of the validated dried blood spot method. Best subset selection multiple linear regression was performed to derive limited sampling strategy (LSS). The equations were constrained to include a maximum of three samples collected within 4 h after the intake to maintain clinical applicability. To assess the predictive performance of LSS, residuals for each patient were calculated based on models fitted to a dataset where that patient was omitted.

Results

The prediction formula for the AUC_0–24 using the time points 0, 2, and 4 h after ingestion (C_0h-C_2h-C_4h) provided the highest correlation with the AUC_0–24 (r² = 0.95): AUC_0–24 = 44.9 + 8.9 × C_0h + 2.1 × C_2h + 7.6 × C_4h. Measures for bias and precision, i.e., median percentage prediction error (MPPE) and median absolute prediction error (MAPE), were 0.4 and 4.8 %, respectively. For the same patients, the correlation between C_24h and AUC_0–24 was worse (r² = 0.77) while MPPE and MAPE were 6.2 and 7.2 %, respectively.

Conclusion

In the outpatient department, a LSS using C_0h-C_2h-C_4h can be used for reliable estimation of the AUC_0–24 of prolonged-release tacrolimus_.

Electronic supplementary material

The online version of this article (doi:10.1007/s00228-015-1863-6) contains supplementary material, which is available to authorized users.

Intra-patient variability in tacrolimus exposure: causes, consequences for clinical management

Tacrolimus (Tac) is widely used for the prevention of rejection after solid organ transplantation. Finding the optimal balance between effective Tac concentrations and toxicity is a challenge and requires therapeutic drug monitoring. In addition to the well-known inter-patient variability, the clinical use of Tac is also complicated by considerable intra-patient variability (IPV) in Tac exposure. Tac IPV is defined as the amount of fluctuation of whole-blood concentrations over a certain period of time during which the Tac dose remains unchanged. A high IPV in Tac exposure has recently been recognized as a strong risk factor for acute rejection and poor long-term kidney transplantation outcome. In addition to non-adherence, several other factors determine the magnitude of the IPV in Tac exposure. Quantification of IPV is easy and can be easily incorporated into everyday clinical practice as a tool for optimizing transplantation outcomes.

Lower variability in 24-hour exposure during once-daily compared to twice-daily tacrolimus formulation in kidney transplantation

INTRODUCTION

Tacrolimus has originally been registered as a twice-daily formulation (Prograf, Tac BID), although a once-daily formulation (Advagraf, Tac QD) is also available. A reduced intrapatient variability of Tac Cmin, a surrogate marker for 24-hour drug exposure (AUC0-24), has been suggested. The variability of AUC0-24 has never been studied prospectively yet. The purpose of this study was to investigate the change in intrapatient variability of Tac AUC0-24 after converting from Tac BID to Tac QD.

METHODS

Forty renal transplant patients on Tac BID were converted on a 1:1 (mg/mg) basis to Tac QD in an investigator-driven comparative pharmacokinetic (PK) study. AUC0-24 was determined five times before and after conversion. Duplicate samples were collected by the patients themselves using the dried blood spot method. The main outcome measure is the change in intrapatient variability of AUC0-24 expressed as coefficient of variation (CV). Moreover, the influence of Cyp3A5 genotype polymorphism on the change in CV was studied.

RESULTS

In total, 400 AUC0-24 profiles were available for analysis. Conversion to Tac QD resulted in a significant improvement in intra-patient CV from 14.1% to 10.9% (P=0.012). Patients with the Cyp3A5*1/*3 genotype (n=11) had a numerically larger improvement in CV than patients with the CYP3A5*3/*3 genotype.

CONCLUSION

Intrapatient CV of Tac AUC0-24 improved after converting from Tac BID to Tac QD in stable renal transplant patients, especially in patients with the CYP3A5*1/3 genotype. Given the very strict protocol of this PK study, this improvement is most likely due to the different intrinsic PK properties of Tac QD and Tac BID.

Conversion from Prograf to Advagraf in stable paediatric renal transplant patients and 1-year follow-up

BACKGROUND

The conversion from Prograf to Advagraf on a 1:1 (mg:mg) basis has been questioned in light of the publication of studies showing a decrease in tacrolimus blood concentrations after the administration of Advagraf.

METHODS

The bioavailability of Prograf and Advagraf was evaluated in an open-label conversion study in 21 stable renal transplant paediatric patients. Serial blood samples for determining tacrolimus levels were collected during a 24-h period before (on Prograf) and after (on Advagraf) conversion. Tacrolimus pharmacokinetic parameters were calculated using a non-compartmental approach and the relative bioavailability calculated. Clinical and analytical data were obtained at 30, 90, 180 and 360 days after study enrolment.

RESULTS

The mean ratio and 90 % confidence interval (CI) for peak plasma drug concentration (C(max)) and the area under the time-concentration curve during the first 24 h (AUC(0-24)) were 81.54 (95 % CI 71.6-92.87) and 87.19 (95 % CI 79.91-95.13), respectively. Renal glomerular filtration rate remained stable over the course of the follow-up. Two patients presented clinical events unrelated to tacrolimus. Tacrolimus levels decreased in the first month, the dose/level ratio increased between months 1 and 6 and slight dose adjustments were required during the follow-up period.

CONCLUSIONS

Our results show that Advagraf bioequivalence cannot be ensured in this population. Significant changes in tacrolimus levels and dose were observed on long-term follow-up.

Conversion from twice- to once-daily tacrolimus in pediatric kidney recipients: a pharmacokinetic and bioequivalence study

BACKGROUND

The objectives of this study were to investigate pharmacokinetic and pharmacogenetic parameters during the conversion on a 1:1 (mg:mg) basis from a twice-daily (Prograf) to once-daily (Advagraf) tacrolimus formulation in pediatric kidney transplant recipients.

METHODS

Twenty-four-hour pharmacokinetic profiles were analyzed before and after conversion in 19 stable renal transplant recipients (age 7-19 years). Tacrolimus pharmacokinetic parameters [area under the concentration-time curve (AUC0-24), minimum whole-blood concentration (Cmin), maximum whole-blood concentration (Cmax), and time to achieve maximum whole-blood concentration (tmax)] were compared between Tac formulations and between CYP3A5 and MDR1 genotypes after dose normalization.

RESULTS

Both AUC0-24 and Cmin decreased after conversion (223.3 to 197.5 ng.h/ml and 6.5 to 5.6 ng/ml; p = 0.03 and 0.01, respectively). However, the ratio of the least square means (LSM) for AUC0-24 was 90.8 %, with 90 % CI limits of 85.3 to 96.7 %, falling within bioequivalence limits. The CYP3A5 genotype influences the dose-normalized Cmin with the twice-daily formulation only.

CONCLUSIONS

Both tacrolimus formulations are bioequivalent in pediatric renal recipients. However, we observed a decrease in AUC0-24 and Cmin after the conversion, requiring close pharmacokinetic monitoring during the conversion period.

Tacrolimus in transplant rejection

INTRODUCTION

Renal transplantation is the best therapy for patients with end-stage renal disease. To avoid graft rejection, adequate immunosuppressive therapy is crucial. Tacrolimus is approved for prophylaxis of transplant rejection in liver, kidney or heart allograft recipients and for the treatment of allograft rejection resistant to treatment with other immunosuppressive medicinal products.

AREAS COVERED

The objective of this review is to summarize the clinical efficacy of tacrolimus in renal transplantation with special emphasis on acute rejection, refractory rejection and nephrotoxicity and post-transplant diabetes mellitus as typical adverse effects of the drug.

EXPERT OPINION

Since its approval in 1994, tacrolimus has proven its efficacy as a cornerstone of modern immunosuppressive therapy not only in numerous randomized clinical trials but also in standard clinical care. Compared with cyclosporine, the use of tacrolimus in renal transplant recipients is associated with a reduced risk for acute rejection, a reduction in the occurrence of steroid-resistant rejection and a better graft function. The avoidance of nephrotoxicity and especially post-transplant diabetes mellitus are of major interest in long-term care of renal transplant recipients.