Conversion of Stable Kidney Transplant Recipients From a Twice-Daily Prograf to a Once-Daily Tacrolimus Formulation: A Short-Term Study on its Effects on Glucose Metabolism

A comprehensive update of the metabolic and toxicological considerations for immunosuppressive drugs used during pancreas transplantation

INTRODUCTION

Despite significant advancements in immunosuppressive regimens and surgical techniques, the prevalence of adverse events related to immunosuppression remains a major challenge affecting the long-term survival rates of pancreas and kidney allografts.

AREAS COVERED

This article presents a comprehensive review of the literature and knowledge (Jan/2012-Feb/2023) concerning glucose metabolism disorders and nephrotoxicity associated with tacrolimus and mammalian target of rapamycin inhibitors (mTORi). Novel signaling pathways potentially implicated in these adverse events are discussed. Furthermore, we extensively examine the findings from clinical trials evaluating the efficacy and safety of tacrolimus, mTORi, and steroid minimization.

EXPERT OPINION

Tacrolimus-based regimens continue to be the standard treatment following pancreas transplants. However, prolonged use of tacrolimus and mTORi may lead to hyperglycemia and nephrotoxicity. Understanding and interpreting experimental data, particularly concerning novel signaling pathways beyond calcineurin-NFAT and mTOR pathways, can offer valuable insights for therapeutic interventions to mitigate hyperglycemia and nephrotoxicity. Additionally, critically analyzing clinical trial results can identify opportunities for personalized safety-based approaches to minimize side effects. It is imperative to conduct randomized-controlled studies to assess the impact of mTORi use and steroid-free protocols on pancreatic allograft survival. Such studies will aid in tailoring treatment strategies for improved transplant outcomes.

Impacts of High Intra- and Inter-Individual Variability in Tacrolimus Pharmacokinetics and Fast Tacrolimus Metabolism on Outcomes of Solid Organ Transplant Recipients

Tacrolimus is a first-line calcineurin inhibitor (CNI) and an integral part of the immunosuppressive strategy in solid organ transplantation. Being a dose-critical drug, tacrolimus has a narrow therapeutic index that necessitates periodic monitoring to maintain the drug’s efficacy and reduce the consequences of overexposure. Tacrolimus is characterized by substantial intra- and inter-individual pharmacokinetic variability. At steady state, the tacrolimus blood concentration to daily dose ratio (C/D ratio) has been described as a surrogate for the estimation of the individual metabolism rate, where a low C/D ratio reflects a higher rate of metabolism. Fast tacrolimus metabolism (low C/D ratio) is associated with the risk of poor outcomes after transplantation, including reduced allograft function and survival, higher allograft rejection, CNI nephrotoxicity, a faster decline in kidney function, reduced death-censored graft survival (DCGS), post-transplant lymphoproliferative disorders, dyslipidemia, hypertension, and cardiovascular events. In this article, we discuss the potential role of the C/D ratio in a noninvasive monitoring strategy for identifying patients at risk for potential adverse events post-transplant.

Conversion From a Twice-Daily to a Once-Daily Tacrolimus Formulation in Kidney Transplant Recipients

BACKGROUND

The aim of the study was to assess bioavailability aspects of tacrolimus formulations during conversion from twice-daily (TAC BID) to once-daily (TAC OD) formulation in 89 stable kidney transplant recipients.

MATERIALS AND METHODS

The study included 89 stable kidney transplant recipients transplanted between 1998 and 2008 (37 female, 52 male, aged 46.0 ± 12.4 years) and followed for 10 years. For a comprehensive comparison of the different tacrolimus formulations, dose-normalized trough levels (ng/mL/mg total daily dose, C/D ratio) and their variability were studied for 10 consecutive visits before and 6 months after conversion.

RESULTS

The mean trough level decreased significantly 14 days after conversion (16%, 5.77 ± 1.94 [5.6, 4.5-6.5] ng/mL, P < .001). There was no significant difference between the tacrolimus trough levels before and 3 months after conversion (6.92 ± 1.89 [6.8, 5.9-8.0] ng/mL, P = .548). The tacrolimus daily dose 3 months after conversion (4.56 ± 1.81 [4.5, 3.5-5.5] mg/d) was significantly higher than the dose before conversion (4.16 ± 1.80 [4.0, 3.0-5.0] mg/d, P = .006). The post-conversion mean TAC trough level (10 measures) (6.6 [6.2-7.0] ng/mL) was similar to preconversion level (6.8 [5.6-7.9] ng/mL, P = .203). C/D ratio as well as C/D intrapatient variability (CV%) did not change during conversion (C/D 1.68 [1.36-2.53] vs 1.74 [1.41 vs 2.31], P = .075; CV% 19.5 [16.4-26.6] vs 24.4 [17.5-28.3], P = .114).

CONCLUSIONS

Conversion from TAC BID to TAC OD is associated with a significant increase in tacrolimus dose during the first 3 months. In a long-term observation both formulations present similar dose-normalized trough levels and variability.

Conversion From Cyclosporine to Once-Daily Tacrolimus on 50:1 mg Basis: A Short-Term Pilot Study

OBJECTIVES

In addition to graft dysfunction, renal transplant recipients on cyclosporine may be switched to tacrolimus to reduce its drug-related secondary clinical effects and undesirable cosmetic side effects. However, the dose level of once-daily tacrolimus for these patients has yet to be established. The objective of this prospective study was to confirm the safety of converting stable renal transplant recipients on cyclosporine to once-daily tacrolimus at a 50:1 mg ratio.

MATERIALS AND METHODS

Our study enrolled 17 patients receiving cyclosporine who were observed for 3 months. Graft biopsies did not reveal any acute rejection, and the conversion ratio to once-daily tacrolimus was 50:1 mg. Dose adjustments were made to achieve a target tacrolimus trough concentration of 3 to 5 ng/mL at 2 weeks, and graft biopsies were taken after the 3-month observation period.

RESULTS

Dose adjustment was required in 7 recipients (41.2%) within 3 months of conversion. None of the recipients had acute cellular rejection or C4d deposition, and the mean estimated glomerular filtration rate of 38.7 ± 11.0 mL/min/1.73 m2 at baseline was significantly improved to 42.0 ± 10.0 mL/min/1.73 m2 at month 3.

CONCLUSIONS

Although recipients of renal transplant can be forced to discontinue cyclosporine administration due to undesirable adverse effects, our study showed that a once-daily dose of tacrolimus may be safe when administered at a conversion ratio of 50:1.

Tacrolimus Utilization and Expenditure in Serbia

Background

Increasing immunosuppressant consumption and expenditure is a quite a challenge in transplantation medicine. The aim of the study was to characterize the utilization and expenditure of tacrolimus, backbone, and standard of care in immunosuppression regimen in Serbian solid organ transplant recipients.

Methods

This study was performed as retrospective cross-sectional study during a 3-year period (from 2013 to 2015) in Serbia. The Anatomical Therapeutic Chemical Classification/Defined Daily Doses (ATC/DDD) international system was used for consumption evaluation.

Results

Two hundred and sixty-nine patients were transplanted in Serbia from 2013 to 2015 (185 recipients from deceased donors and 84 recipients from living donors). Total number of deceased donors in this period was 81. The consumption of tacrolimus increased (from 0.051 DDD/1,000 inhabitants/day to 0.069 DDD/1,000 inhabitants/day in 2013 and 2015, respectively). The total cost of tacrolimus was also increased; from 1,206,816€ to 1,483,472€ in 2013 and 2015, respectively. On the other hand, the number of all new solid organ transplants (from deceased and living donors) per million population per year was decreased from 17.39 to 10.02, from 2013 to 2015, respectively.

Conclusion

In spite downward trend in the number of solid organ transplants, tacrolimus consumption and expenditure in the examined 3-year period in Serbia increased. Since tacrolimus is a high-cost and life-preserving drug, its increasing utilization and expenditure will most likely continue consuming an enhancing share of Serbian pharmaceutical expenditure, as well as its health care, as a whole.

Early or Late Conversion From Tac-BD to Tac-BD in Renal Transplantation: When is the Right Time?

BACKGROUND

Increasing numbers of renal transplant recipients are converted from Prograf (Astellas Pharma, Tokyo, Japan) (tacrolimus twice daily [Tac-BD]) to Advagraf (Astellas) (tacrolimus once daily [Tac-QD]), but the optimal time for conversion is as yet unclear. This study aimed to investigate the correlation between the time of conversion from Tac-BD to Tac-QD after renal transplant and the dosing requirements, tacrolimus levels, renal function, and clinical outcomes.

METHODS

Since September 2008, 125 renal transplant patients were converted from Tac-BD to Tac-QD and followed up for 2 years after conversion. Patients were split into early (0 to 12 months) and late (>12 months) conversion groups. Demographics, Tac-QD dose, trough levels, graft function, and patient and graft outcome were prospectively collected.

RESULTS

Forty-four patients (35.2%) were converted early (3.82 ± 3.24 months), whereas 81 (64.8%) patients were converted late (77.35 ± 53.71 months). Tac-BD dose before conversion was higher in the early group (8.70 ± 6.34 vs 4.44 ± 2.15 mg) as was the initial Tac-QD dose (8.66 ± 6.20 vs 4.37 ± 2.04 mg, P < .0001), and remained higher for 18 months after conversion, as did the serum tacrolimus trough level levels. Renal function, acute rejection, and patient and graft survival were comparable between the groups.

CONCLUSIONS

Patients can be safely converted to Tac-QD within the first year post-transplantation, without adverse effects on clinical outcome, despite the higher doses and tacrolimus levels for the first 18 months.

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 of twice-daily tacrolimus to once-daily tacrolimus formulation in stable pediatric kidney transplant recipients: pharmacokinetics and efficacy

The pharmacokinetics, efficacy and safety of once-daily tacrolimus formulation (Tac-OD) were assessed in 34 stable pediatric kidney transplant recipients. Enrolled patients received their dose of twice-daily tacrolimus formulation (Tac-BID) on study Days 0 through 7. On the morning of study Day 8, the total daily doses for patients were converted to Tac-OD on a 1:1 basis and maintained on a once-daily morning dosing regimen. Tacrolimus pharmacokinetic profiles were obtained on study Days 7, 14 and 28 (after dose adjustment). Although the mean C0 concentrations (4.10 ± 1.16-3.53 ± 1.10 ng/mL, p = 0.004), and AUC0-24 (151.8 ± 41.6-129.8 ± 39.3 ng h/mL, p < 0.001) were decreased significantly after a 1:1 based conversion, there was high interindividual variability. The dose of Tac-OD was decreased in 26.5% and increased in 44.1% of patients. The resultant tacrolimus dose and pharmacokinetic profiles on study Day 28 were comparable to those on Day 7. There were no serious adverse events. In conclusion, Tac-BID can be safely converted to Tac-OD in stable pediatric kidney transplant patients with the heightened therapeutic drug monitoring. Effects of drug conversion on the cardiovascular risk factors, neurological side effects and adherence should be further evaluated.

Validity of glycated haemoglobin to diagnose new onset diabetes after transplantation

Diagnosing new onset diabetes after transplantation (NODAT) by glycated haemoglobin (HbA1c) has not been validated against the gold-standard oral glucose tolerance test (OGTT). We analysed the predictive and optimum value of HbA1c to diagnose NODAT amongst nondiabetic renal transplant recipients. Assessment of glucose metabolism (OGTT and HbA1c) was prospectively undertaken at 3 and 12 months post-transplantation in 71 nondiabetic renal transplant recipients. Receiver operator characteristic (ROC) curve analyses were performed to determine accuracy, sensitivity, specificity and area under curve (c-statistic). Incidence of NODAT at 3 and 12 months post-transplantation was 14.3% and 9.5% respectively. At 3 months, optimum HbA1c cut-off value for predicting NODAT based on fasting glucose was 7.35 [AUC 1.00 (sensitivity 100.0%, specificity 100.0%, P = 0.004)] and for postprandial glucose-defined NODAT was 6.20 [AUC 0.98 (sensitivity 100.0%, specificity 88.9%, P < 0.001)]. At 12 months, optimum HbA1c cut-off value for both fasting- and postprandial glucose-defined NODAT was 6.45 [AUC 0.92 (sensitivity 100.0%, specificity 87.5%, P = 0.048) and AUC 0.84 (sensitivity 75.0%, specificity 89.5%, P = 0.026) respectively]. Concordance between diagnosis of NODAT (OGTT+, HbA1c+) and nondiagnosis of NODAT (OGTT-, HbA1c-) was 88.9% and 98.7% respectively. To conclude, HbA1c (≥6.5%) can be utilized to diagnose NODAT beyond 3 months post-transplantation but the OGTT remains the gold-standard tool.