Reduced C0 concentrations and increased dose requirements in renal allograft recipients converted to the novel once-daily tacrolimus formulation. Transplantation. 2010;90:523-529. [PMID: 20592652 DOI: 10.1097/tp.0b013e3181e9feda]

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).

Pharmacokinetics of a Once Daily Tacrolimus Formulation in First Nations and Caucasian Liver Transplant Recipients

BACKGROUND

Patient ethnicity may influence the pharmacokinetics (PK) of tacrolimus. The Canadian First Nations (FN) constitute a large and increasing segment of the liver transplant population.

OBJECTIVE

To determine whether PK differences exist for a once daily, extended-release formulation of tacrolimus in FN compared to Caucasian (Cauc) liver transplant recipients.

METHODS

Following a 1:1 mg conversion from immediate- to extended-release tacrolimus and achievement of a steady state on the latter formulation, blood samples were drawn at 0, 1, 2, 4, 6, 8 and 24 hours for whole blood tacrolimus levels by commercial immunoassay. CYP3A4 and CYP3A5 allele analyses were performed by polymerase chain reactions.

RESULTS

Nineteen subjects participated in the study (7 FN and 12 Cauc). Unlike Cauc patients, post-conversion Cmin levels did not decrease and were less variable in FN patients. FN patients also had significant shorter Tmax times (1.6±0.2 hours versus 2.8±0.3 hours, p<0.05). Oral clearance, Vd, AUCs, Cmax and Cmin levels were similar in the two cohorts. CYP3A4 genotypes were C/C in both cohorts while the CYP3A5 *1/*3 allele, was present in 2/5 FN and 0/9 Cauc.

CONCLUSIONS

Conversion from immediate- to extended-release tacrolimus results in no significant decrease in Cmin levels, less variable Cmin levels and a shorter time to Tmax in FN compared to Cauc liver transplant recipients.

Thirty Years of Tacrolimus in Clinical Practice

Tacrolimus was discovered in 1984 and entered clinical use shortly thereafter, contributing to successful solid organ transplantation across the globe. In this review, we cover development of tacrolimus, its evolving clinical utility, and issues affecting its current usage. Since earliest use of this class of immunosuppressant, concerns for calcineurin-inhibitor toxicity have led to efforts to minimize or eliminate these agents in clinical regimens but with limited success. Current understanding of the role of tacrolimus focuses more on its efficacy in preventing graft rejection and graft loss. As we enter the fourth decade of tacrolimus use, newer studies utilizing novel combinations (as with the mammalian target of rapamycin inhibitor, everolimus, and T-cell costimulation blockade with belatacept) offer potential for enhanced benefits.

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.

Once daily tacrolimus conversion in lung transplantation: A prospective study on safety and medication adherence

BACKGROUND

Lung transplantation (LTx) requires a calcineurin inhibitor-based immunosuppressive regimen. A once daily (QD) tacrolimus regimen was developed to increase medication adherence. However, data concerning its safety and efficacy in LTx are lacking.

METHODS

In this prospective study, stable LTx patients were consecutively converted from twice daily (BID) tacrolimus to QD tacrolimus on a 1 mg:1 mg basis. Trough level (C_min), renal function, cholesterol, fasting glucose, potassium and lung function were monitored six months before and up to one year after conversion. Adherence and its barriers were assessed by self-reported questionnaires (Basel Assessment of Adherence to Immunosuppressive Medications Scale (BAASIS) and Identification of Medication Adherence Barriers questionnaire (IMAB)) and blood-based assays (mean C_min and coefficient of variation (CV)).

RESULTS

We included 372 patients, in whom we observed a decrease in tacrolimus C_min of 18.5% (p < 0.0001) post-conversion, requiring subsequent daily dose adaptations in both cystic fibrosis (CF) (n = 72) and non-CF patients (n = 300). We observed a small decrease in eGFR one year post-conversion (p = 0.024). No significant changes in blood creatinine, potassium, fasting glucose, cholesterol or rate of lung function decline were observed. In a subgroup of 166 patients, significantly fewer patients missed doses (8.4% vs. 19.3%, p = 0.016) or had irregular intake post-conversion (19.3% vs. 32.5%, p = 0.019). Mean C_min and CV, as well as the total number of barriers, also decreased significantly post-conversion.

CONCLUSIONS

In LTx, conversion from BID to QD tacrolimus (1 mg:1 mg) requires close monitoring of tacrolimus C_min. QD tacrolimus after transplantation is safe with respect to renal function, metabolic parameters and allograft function and improves LTx recipient adherence.

Comparison of the Impact of Pharmacogenetic Variability on the PK of Slow Release and Immediate Release Tacrolimus Formulations

Tacrolimus-modified release formulations allow for once-daily dosing, and adherence is better compared to the twice-daily immediate release formulation. When patients are switched from one formulation to another, variable changes in drug concentrations are observed. Current data suggest that the changes in drug exposure are larger in patients who express the CYP3A5 enzyme (CYP3A5 *1/*3 or *1/*1) compared to nonexpressers (CYP3A5*3/*3). Possibly, these differences are due to the fact that in the upper region of the small intestine CYP3A activity is higher, and that this expression of CYP3A decreases towards the more distal parts of the gut. Modified release formulations may therefore be subject to a less presystemic metabolism. However, the full implications of pharmacogenetic variants affecting the expression and function of drug transporters in the gut wall and of enzymes involved in phase I and phase II metabolism on the different formulations are incompletely understood, and additional studies are required. Conclusions: In all patients in whom the formulation of tacrolimus is changed, drug levels need to be checked to avoid clinically relevant under- or overexposure. In patients with the CYP3A5 expresser genotype, this recommendation is even more important, as changes in drug exposure can be expected.

Once-Daily versus Twice-Daily Tacrolimus in Kidney Transplantation: A Systematic Review and Meta-analysis of Observational Studies

BACKGROUND

Tacrolimus is the most commonly prescribed medication in initial immunosuppressive regimens to prevent acute rejection in kidney transplant recipients (KTRs). Tacrolimus was originally available as an immediate-release formulation (IR-Tac) given twice daily. Extended-release tacrolimus (ER-Tac) given once daily was later developed with the expectation of improved medication adherence. Data from observational studies, which compared outcomes between ER-Tac and IR-Tac in different populations of KTRs including those who are unlikely to be enrolled in randomized clinical trials, have been reported.

PURPOSE

To evaluate the incidence of biopsy-proven acute rejection (BPAR) at 12 months together with other outcomes reported in observational studies among adult KTRs who received ER-Tac compared to IR-Tac.

METHODS

In accordance with the recommendations of the Cochrane Collaboration and the Meta-analysis of Observational Studies in Epidemiology, we systematically reviewed all observational studies that compared clinical outcomes between ER-Tac and IR-Tac in KTRs. The systematic searches were conducted on PubMed, EMBASE, Scopus, and Web of Science without language restriction. Reference lists were also searched and reviewed. Data were extracted for BPAR, graft survival, patient survival, estimated glomerular filtration rate (eGFR), serum creatinine (Scr), creatinine clearance (CrCl), at different times after kidney transplantation (KT). A meta-analysis was performed to integrate the results from the eligible studies. This study is registered with PROSPERO, number CRD42019135705.

RESULTS

From the 1401 articles screened, 10 observational studies in KTRs who received tacrolimus were included. The pooled results showed significantly lower BPAR with ER-Tac than with IR-Tac at 12 months post-KT (5 studies, n = 659; RR, 0.69; 95% CI 0.51-0.95; p = 0.02; I² = 0%). No significant differences in BPAR at other time points after KT were found. Graft survival, patient survival, Scr, and eGFR were comparable between groups at different times over approximately 1 year after transplantation.

CONCLUSIONS

Based upon currently available evidence in observational studies, 30% lower risk of BPAR was observed in ER-Tac group compared with IR-Tac group at 12 months post-KT, while there was no significant difference in BPAR risk at any other studied time points. No differences in graft- and patient-survival rates and kidney function were found. Given the limitations of observational studies to make causal inference, as well as quality limitations among the included studies, caution should be exercised in interpreting these findings.

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.

The association between trough blood concentration and systemic exposure of tacrolimus: Comparison between once-daily (Advagraf®) and twice-daily (Prograf®) formulation in de novo kidney transplant recipients

Available data of early conversion from twice-daily tacrolimus (TAC-BID) to once-daily tacrolimus (TAC-OD) in de novo kidney transplant (KT) recipients are limited. We conducted a prospective study of early conversion to TAC-OD in de novo KT recipients. Eligible patients were enrolled to receive TAC-BID (Prograf®) and then converted to TAC-OD (Advagraf®) by 1:1 ratio, approximately 14 days after KT (range 9-22). Blood samples were investigated for pharmacokinetic parameters before and 7-14 days after the conversion. Fifteen patients were included and provided AUC_0-24 of 202.9 ± 44.4 ng h/mL for TAC-BID (pre-conversion) and 193.0 ± 63.4 ng h/mL for TAC-OD (post-conversion) (p = 0.41). Mean trough blood concentration (C_min) of TAC-BID and TAC-OD was 6.4 ± 1.4 ng/mL and 4.9 ± 1.6 ng/mL (p = 0.01). Correlation coefficient (r) between C_min and AUC_0-24 of TAC-BID and TAC-OD were 0.620 and 0.875. Additional analysis found that patients with a drop of C_min > 30% had a significant lower AUC_0-24 after conversion. Renal function remains stable. We conclude that early conversion to TAC-OD is safe and well tolerated with an indifferent systemic exposure. However, patients with a drop of C_min > 30% after conversion to TAC-OD will require additional dose adjustment.

Optimization of tacrolimus in kidney transplantation: New pharmacokinetic perspectives

Tacrolimus is the cornerstone of immunosuppressive therapy after kidney transplantation (KT), but its use is complicated by a narrow therapeutic index and high inter- and intra-patient pharmacokinetic variability. There are three available oral formulations of tacrolimus: immediate-release tacrolimus (IR-Tac), extended-release tacrolimus (ER-Tac) and a MeltDose® (LCPT) formulation, the latter favoring a prolonged drug release and increased bioavailability. The time-concentration curves of these formulations are different. Compared with IR-Tac and ER-Tac, LCPT has a relatively flat pharmacokinetic profile with less fluctuation between trough and peak exposures, and a delayed peak concentration. This translates to a more stable delivery of tacrolimus and may alleviate the risk of underexposure and allograft rejection or overexposure and toxicity. The once-daily formulation of both ER-TAC and LCPT may also offer a potential advantage on patient adherence. Fast metabolizers of tacrolimus, the elderly, and human leukocyte antigen-sensitized patients are at risk of poorer outcomes after KT, possibly associated with a different exhibited pharmacokinetics of tacrolimus or different requirements in terms of exposure. Simple, practical strategies are needed to identify patients at risk of suboptimal KT outcomes and those who would benefit from a more proactively personalized approach to tacrolimus treatment. This review aims to increase awareness of the link between the pharmacokinetics of oral tacrolimus formulations and the clinical needs of patients after KT, particularly among those who have clinically significant pharmacokinetic variation of tacrolimus.

Effect on Dosage Change and Intrapatient Variability After Conversion From Twice-Daily to Once-Daily Tacrolimus Among Thai Kidney Transplant Patients With and Without CYP3A4/5 Inhibitors

BACKGROUND

Converting to once-daily tacrolimus (Advagraf [Adv]) among renal transplant patients results in better drug adherence. Data regarding dosage and intrapatient variability changes after conversion among patients with CYP3A4/5 inhibitors (CYPinh) is lacking.

METHOD

A retrospective chart review among all kidney transplant recipients at Siriraj Hospital was performed. Patients were enrolled who had been on standard release twice-daily tacrolimus and subsequently replaced it with Adv for at least 6 months with no change in CYPinh type or dosage.

RESULTS

Fifty-three patients were eligible. Conversion occurred at a mean time after transplant of 51.25 (SD, 40.30) months. Ten patients (18.9%) did not receive CYPinh, while 19 (35.8%), 21 (39.6%), and 3 (5.7%) received diltiazem, ketoconazole or fluconazole, and both diltiazem and ketoconazole, respectively. After conversion, median increment of tacrolimus dosage was 14.29% (-50% to 167%), while no significant change in IPV was demonstrated (17.46% [SD, 11.25%] vs 14.83% [SD, 6.78]; P = .11). Patients receiving azole had less dosage increment than those not receiving CYPinh (P = .02). After conversion, 14 of 22 patients with IPV > 17% (63.6%) had reduced IPV to ≤ 17%, while 25.8% of patients with lower IPV had an increase in IPV > 17%.

CONCLUSION

Conversion to Adv required a dosage increment of 30% to achieve the same trough level. Concomitant use of CYPinh significantly reduced tacrolimus dose increment. A trend was noted toward improved IPV after conversion. Conversion to Adv resulted in better IPV among patients with high IPV while receiving twice-daily tacrolimus.

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

In this non-randomized extension study of a randomized controlled trial we converted 87 stable long-term kidney transplant recipients (KTR) from either ciclosporin (CSA, n = 28) or tacrolimus (TAC, n = 59) to TAC modified release (TAC MR4) to study the characteristics of TAC trough levels after conversion with the primary endpoint graft function after 12 months. TAC MR4 consumption was calculated by level-to-dose ([ng/mL]/[mg/d]) and concentration-to-dose ([mg/kg])/d) ratios. Influences of ABCB1 single nucleotide polymorphisms (2677G>T/A, 1236C>T, 3435C>T) on TAC metabolism were studied. Graft function of KTR converted from CSA to TAC MR4 significantly declined over 12 months, and remained unchanged after conversion from TAC to TAC MR4. Conversion from CSA to TAC MR4 resulted in supra therapeutic- and conversion from TAC to TAC MR4 in low trough levels. We could not find associations of ABCB1 genotypes and TAC MR4 trough levels. Adverse events and errors with TAC/TAC MR4 intake were common. In stable long-term KTR conversion from TAC to TAC MR4 is feasible. For conversion from CSA we suggest a rate of 1:40 for a rough estimation of TAC MR4 target doses.

Comparative clinical trial of the variability factors of the exposure indices used for the drug monitoring of two tacrolimus formulations in kidney transplant recipients

BACKGROUND

Several studies found differences in tacrolimus whole blood trough levels (C0) or area-under-the curve (AUC) between the twice-daily (Tac-BID) and once-daily (Tac-OD) formulations given to kidney transplant recipients at equal doses. As C0 is widely used as a surrogate of the AUC for individual dose adjustment, this study investigated the correlation and proportionality between C0 and the 24h-AUC, depending on the formulation, time post-transplantation, pharmacogenetics traits and other individual characteristics.

METHODS

45 adult kidney transplant recipients were randomized to receive either Tac OD or Tac BID. On days 8±1 (D8) and 90±3 (month 3, M3), blood samples were collected over 24h in both groups. Tacrolimus concentrations were determined using HPLC-MS/MS and common CYP3A5, CYP3A4 and ABCB1 genotypes characterized using allelic discrimination assays. Tacrolimus population pharmacokinetics was studied in the two patient groups using the Iterative Two Stage (ITS) technique, considering a one-compartment model with two gamma laws to describe the absorption phase. Bayesian estimation based on the C0, C1h and C3h concentrations was employed to estimate individual Tac AUC_0-12h and AUC_12-24h (for Tac BID), or AUC_0-24h (for Tac OD). Multiple linear regression was used to evaluate the influence of Tac formulation, post-transplantation period, recipient gender, existing glucose metabolism disorders, and CYP3A5, CYP3A4 and ABCB1 genotypes on C0, AUC_0-24h and the AUC-to-trough concentration ratios.

RESULTS

The Full Analysis Set comprised 22 patients on Tac OD and 20 on Tac BID. Tac exposure indices as well as their time evolution were similar in the two groups. Multi-linear modeling analysis showed that the Tac dose was higher with Tac-OD than Tac-BID, on D8 than at M3 and in CYP3A5 expressors (p<0.0001 for all). No such influence was found on C0 or C24h, while the AUC_0-24h was significantly higher on D8 than at M3. The AUC_0-24h/C0 ratio was not affected by the drug formulation and the polymorphisms studied, but it was significantly lower on D8 than at M3 (p=7.8×10^-5). In contrast, both the post-transplantation period (p=1.53×10^-4), and CYP3A5 expression (p=0.003) had a significant influence on the AUC_0-24h/C24h ratio, explaining 19% and 12% of its variability, respectively. Consistently, for both Tac formulations, the AUC_0-24h was better correlated with C24h than C0, and for Tac-BID the AUC_0-12h was better correlated with C12h than C0.

CONCLUSIONS

This study confirms that the precisely timed 12h- or 24h-post-dose blood concentration (as opposed to the vaguely defined 'trough level') is a convenient surrogate of the 24h-AUC of tacrolimus for the two TAC formulations over the first 3 months post-transplantation. Still, for a given C24h value, AUC_0-24h was higher on D8 and in CYP3A5 expressors. Bayesian estimation of AUC_0-12h for TAC BID and AUC_0-24h for TAC OD is feasible using only 3 time points within the first 3h, thus giving access to the actual overall exposure.

Trough level from twice daily to once daily tacrolimus in early conversion kidney transplant recipients: a prospective study

Background Early conversion from twice-daily tacrolimus (TAC-BID) to once-daily tacrolimus (TAC-OD) provides a greater benefit of reducing under-exposure of TAC-OD during the first period after transplantation. Information regarding the conversion dose among Asian kidney transplant recipients is still limited. Objective This study aimed to compare the trough levels (C_min) of TAC-BID (Prograf^®) and TAC-OD (Advagraf^®). The values were obtained from early conversion intervention by 1:1 milligram per-milligram. Setting A university-based hospital. Method This study employed a single-center, open-label, prospective and single-armed design. Fifteen de novo standard risk kidney transplant recipients were enrolled. Fourteen days after transplantation, the C_min of TAC-BID (pre-conversion C_min) was determined. Subsequently, TAC-BID was converted to TAC-OD with a similar dose. The C_min of TAC-OD was first measured at a steady state (immediate post-conversion C_min) and compared. All enrolled patients received therapeutic monitoring at the first and second months. Main outcome measure Pre-conversion C_min of TAC-BID and immediate post-conversion C_min of TAC-OD. Results The immediate post-conversion C_min was found to be 23% lowered than the pre-conversion C_min. However, the C_min of TAC-OD was found to be similar to the pre-conversion C_min compared during the follow-up period. Renal function was found to be stable in all patients over 2 months. Conclusion Early conversion therapy was associated with a significantly lower immediate post-conversion C_min but comparable C_min throughout the follow-up period. The "one to one conversion ratio" from TAC-BID to TAC-OD could be performed among Asian de novo kidney transplant recipients at an early period after transplantation.

Results of ASERTAA, a Randomized Prospective Crossover Pharmacogenetic Study of Immediate-Release Versus Extended-Release Tacrolimus in African American Kidney Transplant Recipients

BACKGROUND

Differences in tacrolimus dosing across ancestries is partly attributable to polymorphisms in CYP3A5 genes that encode tacrolimus-metabolizing cytochrome P450 3A5 enzymes. The CYP3A5*1 allele, preponderant in African Americans, is associated with rapid metabolism, subtherapeutic concentrations, and higher dose requirements for tacrolimus, all contributing to worse outcomes. Little is known about the relationship between CYP3A5 genotype and the tacrolimus pharmacokinetic area under the curve (AUC) profile in African Americans or whether pharmacogenetic differences exist between conventional twice-daily, rapidly absorbed, immediate-release tacrolimus (IR-Tac) and once-daily extended-release tacrolimus (LifeCycle Pharma Tac [LCPT]) with a delayed absorption profile.

STUDY DESIGN

Randomized prospective crossover study.

SETTING & PARTICIPANTS

50 African American maintenance kidney recipients on stable IR-Tac dosing.

INTERVENTION

Recipients were randomly assigned to continue IR-Tac on days 1 to 7 and then switch to LCPT on day 8 or receive LCPT on days 1 to 7 and then switch to IR-Tac on day 8. The LCPT dose was 85% of the IR-Tac total daily dose.

OUTCOMES

Tacrolimus 24-hour AUC (AUC_0-24), peak and trough concentrations (C_max and C_min), time to peak concentration, and bioavailability of LCPT versus IR-Tac, according to CYP3A5 genotype.

MEASUREMENTS

CYP3A5 genotype, 24-hour tacrolimus pharmacokinetic profiles.

RESULTS

∼80% of participants carried the CYP3A5*1 allele (CYP3A5 expressers). There were no significant differences in AUC_0-24 or C_min between CYP3A5 expressers and nonexpressers during administration of either IR-Tac or LCPT. With IR-Tac, tacrolimus C_max was 33% higher in CYP3A5 expressers compared with nonexpressers (P=0.04): With LCPT, this difference was 11% (P=0.4).

LIMITATIONS

This was primarily a pharmacogenetic study rather than an efficacy study; the follow-up period was too short to capture clinical outcomes.

CONCLUSIONS

Achieving therapeutic tacrolimus trough concentrations with IR-Tac in most African Americans results in significantly higher peak concentrations, potentially magnifying the risk for toxicity and adverse outcomes. This pharmacogenetic effect is attenuated by delayed tacrolimus absorption with LCPT.

TRIAL REGISTRATION

Registered at ClinicalTrials.gov, with study number NCT01962922.

A Steady-State Head-to-Head Pharmacokinetic Comparison of All FK-506 (Tacrolimus) Formulations (ASTCOFF): An Open-Label, Prospective, Randomized, Two-Arm, Three-Period Crossover Study

This two-sequence, three-period crossover study is the first pharmacokinetic (PK) study to compare all three innovator formulations of tacrolimus (twice-daily immediate-release tacrolimus capsules [IR-Tac]; once-daily extended-release tacrolimus capsules [ER-Tac]; novel once-daily tacrolimus tablets [LCPT]). Stable renal transplant patients were dosed with each drug for 7 days, and blood samples were obtained over 24 h. Thirty subjects were included in the PK analysis set. A conversion factor of 1:1:0.80 for IR-Tac:ER-Tac:LCPT was used; no dose adjustments were permitted during the study. The median (interquartile range) total daily dose was 6.0 (4.0-8.0) mg for IR-Tac and ER-Tac and 4.8 (3.3-6.3) for LCPT. Significantly higher exposure on a per milligram basis, lower intraday fluctuation and prolonged time (Tmax ) to peak concentration (Cmax ) were found for LCPT versus IR-Tac or ER-Tac. ER-Tac showed no differences versus IR-Tac in exposure, Cmax , Tmax or fluctuation. The observed exposure of IR-Tac was used to normalize exposure for LCPT and ER-Tac, resulting in the following recommended total daily dose conversion rates: IR-Tac:ER-Tac, +8%; IR-Tac:LCPT, -30%; ER-Tac:LCPT, -36%. After exposure normalization, Cmax was ~17% lower for LCPT than for IR-Tac or ER-Tac; Cmin was ~6% lower for LCPT compared with IR-Tac and 3% higher compared with ER-Tac.

Pharmacokinetic Profile of Twice- and Once-daily Tacrolimus in Pediatric Kidney Transplant Recipients

BACKGROUND

The aim of this study was to assess the differences in pharmacokinetic (PK) profiles after the 1:1 ratio-based conversion from a twice-daily to a once-daily tacrolimus formulation (TD-TAC and OD-TAC, respectively) in pediatric recipients of kidney transplants.

METHODS

TD-TAC was initially administered to 29 pediatric patients who underwent kidney transplantations between April 2010 and September 2015 and were then subsequently switched to OD-TAC. The switch dose ratio was 1:1, and the 24-hour complete PK parameter assessment was performed before and after the regimen was changed from TD-TAC to OD-TAC.

RESULTS

The mean total daily dose at baseline was 5.5 ± 2.9 mg (0.18 ± 0.10 mg/kg body weight). Consecutive PK studies revealed no significant difference in the mean time to achieve maximum concentrations and the area under the concentration-time curve from 0 to 24 hours (AUC_0-24) of both drug formulations. However, the mean trough concentration (C_min) and the maximum concentration of OD-TAC were 22% and 6% lower and higher, respectively, than those of TD-TAC. Therefore, a better correlation was observed between the AUC_0-24 and C_min of OD-TAC than between those of TD-TAC.

CONCLUSIONS

After the change from TD-TAC to OD-TAC, the AUC_0-24 values were equivalent despite a 22% reduction in C_min. C_min may therefore be an excellent predictor in the therapeutic drug monitoring of OD-TAC because of its superior correlation with AUC_0-24.

Conversion From Twice-Daily to Once-Daily Tacrolimus in Stable Kidney Graft Recipients

INTRODUCTION

Immunosuppression has a pivotal role in kidney transplantation. The new prolonged-release formulation of tacrolimus was developed to provide a more convenient once-daily dosing to improve patient adherence.

METHODS

We selected 60 stable kidney transplant recipients who underwent tacrolimus conversion in our unit. Conversion was made on a 1 mg:1 mg basis in 66.7% of patients (n = 40) and on a 1 mg:1.1 mg basis in the remaining 33.3% (n = 20). Clinical and analytical data at conversion and postconversion was analyzed retrospectively to evaluate the efficacy and safety of conversion from tacrolimus twice-daily to once-daily formulation.

RESULTS

A significant reduction in tacrolimus blood levels requiring an increase in tacrolimus daily dose was observed postconversion. Postconversion tacrolimus blood level reduction >25% was significantly higher in the conversion group 1 mg:1 mg basis (P = .004). In patients converted 1 mg:1 mg, female sex and higher tacrolimus level at conversion were significant risk factors for a reduction >25% in tacrolimus blood levels after conversion. No significant change was detected between mean glomerular filtration rate at conversion (57 mL/min) and at 3, 6, and 9 months postconversion.

CONCLUSIONS

Once-daily tacrolimus at similar doses to the twice-daily formulation is an efficient and safe treatment option. Conversion made on 1 mg:1.1 mg basis seems advantageous at least in some patients.

Effect of ABCB1 diplotype on tacrolimus disposition in renal recipients depends on CYP3A5 and CYP3A4 genotype

The relevance of most genetic polymorphisms beyond CYP3A5*1 on tacrolimus disposition remains unclear. We constructed a predictive mixed model for tacrolimus dose-corrected trough concentration (C₀/dose) at months 3, 12 and 24 after transplantation in a retrospective cohort of 766 predominantly Causasian adult renal recipients (n=2042 trough concentrations). All patients were genotyped for 32 single-nucleotide polymorphisms with a proven or possible relevance to tacrolimus disposition based on the previous studies. Of these, ABCB1, ABCC2, OATP1B1, COMT, FMO, PPARA and APOA5 were analyzed as (functional) diplotype groups. Predictors of C₀/dose were CYP3A5*1, hematocrit, age, CYP3A4*22, use of concomitant CYP3A4 inhibitor or inducer, ALT, estimated glomerular filtration rate, tacrolimus formulation (once vs twice daily), ABCB1 diplotype and time after transplantation. The effect of ABCB1 diplotype was small but strongly accentuated in CYP3A4*22 carriers and non-existent in CYP3A5 expressors. ABCC2 diplotype had a limited effect on C₀/dose that was only statistically significant in CYP3A5 non-expressors.

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.

Advagraf(®) , a once-daily prolonged release tacrolimus formulation, in kidney transplantation: literature review and guidelines from a panel of experts

The efficacy and safety of tacrolimus twice-a-day (BID) and once-a-day (QD) formulations are similar. However, the available information regarding the initiation and management of tacrolimus QD is sparse and practical information is lacking. A panel of French experts extensively reviewed the available literature on tacrolimus pharmacokinetics, clinical efficacy, and safety in kidney transplantation and, based on their own day-to-day experience, provided the practitioners with practical guidelines for the daily use and management of tacrolimus QD in de novo initiation or early conversion.

Recent trials in immunosuppression and their consequences for current therapy

PURPOSE OF REVIEW

Although the scarcity of clinical trials with de-novo immunosuppression has been typical over the last 2 years, several attempts have been made in drug conversion, dosing optimization, and bioequivalence. On the basis of recent clinical and animal studies, future directions of management and treatment are outlined.

RECENT FINDINGS

Studies with new tacrolimus formulations showed better bioavailability and lower doses, which might translate into less toxicity. The long-term results of studies with costimulation blockade confirmed their safety and efficacy. Calcineurin inhibitor (CNI)-free regimens based on mTOR inhibitors were shown to be associated with increased risk of the humoral response. Therefore, ongoing trials are predominantly designed to minimize calcineurin inhibitor dose only. Biologics, such as B-cell-specific agents (bortezomib and rituximab) and complement inhibitors (eculizumab) used to treat antibody-mediated rejection, recurrence of glomerulonephritis, are shifted to more preventive applications. The pretransplant quantification of alloreactive memory/effector T cell response may help to better stratify a patient's immunologic risk and allow for drug minimization.

SUMMARY

Despite clinical trials with innovative protocols with already established agents, tacrolimus-based and induction-based protocols have been shown to be the mainstay of immunosuppressive regimens. In the future, research aims to focus on biomarker-driven immunosuppression and cell therapy approaches.

Performance of modified-release tacrolimus after conversion in liver transplant patients indicates potentially favorable outcomes in selected cohorts

Clinical outcomes, dose changes, and dose-equalized tacrolimus concentrations were examined sequentially in 129 liver transplantation (LT) recipients after successful conversion to once daily modified-release tacrolimus either early (within 1 month) or late (>1 month) after LT. The data were compared with data for a group of 60 patients maintained on twice daily conventional-release tacrolimus. Formulation- and time-dependent changes in dose requirements for once and twice daily tacrolimus differed after transplantation. A 1.7-fold initial increase in the median daily dose was required to achieve target tacrolimus concentrations in the early-conversion cohort (P = 0.006), whereas a 1.25-fold increase was required for those converted later (P = 0.013 and P < 0.001 for the difference). In the subsequent 2 months, the median daily dose fell by 20% in the early-conversion cohort, remained stable for the late-conversion cohort, but rose by 33% with conventional therapy. Lower median dose-equalized concentrations persisted for up to 3 months after the conversion to modified-release therapy. Sex, ethnicity, and the underlying liver disease did not significantly affect these variables. The frequency of treated biopsy-proven acute rejection episodes fell approximately 4-fold after the conversion to modified-release tacrolimus, most notably in the late-conversion cohort, which experienced a high incidence of rejection before conversion. Posttransplant increases in serum creatinine concentrations were smaller after the introduction of modified-release tacrolimus in the late-conversion group (0.7 versus 4 mg/mL for twice daily tacrolimus over 6 months). Reduced interpatient variability in tacrolimus concentrations was evident in the early-conversion cohort versus the twice daily cohort. A decline in intrapatient variability accompanied the reduction in acute rejection in the late-conversion cohort. Our data highlight potential benefits for the rejection rate and renal function on conversion to once daily modified-release tacrolimus late after LT.

Safety and efficacy of conversion from twice-daily tacrolimus to once-daily tacrolimus one month after transplantation: randomized controlled trial in adult renal transplantation

PURPOSE

The purpose of this study was to compare once-daily tacrolimus with twice-daily tacrolimus in terms of safety, efficacy, and patient satisfaction.

MATERIALS AND METHODS

This prospective, randomized, open-label, multicenter study was conducted at three institutes. Patients in the investigational group were converted from tacrolimus twice daily to the same dose of extended-release tacrolimus once daily at 1 month post-transplantation, while patients in the control group were maintained on tacrolimus twice daily. The efficacies, safeties, and patient satisfaction for the two drugs at 6 months post-transplantation were compared.

RESULTS

Sixty patients were enrolled and randomized to the investigational group (28 of 29 patients completed the study) or the control group (26 of 31 patients completed the study). At 6 months post-transplantation, composite efficacy failure rates including the incidences of biopsy-confirmed acute rejection in the investigational and control groups were 0% and 10.7%, respectively; patient survival was 100% in each group. No difference in estimated glomerular filtration rate values were observed at 6 months post-transplantation (p=0.97). The safety and satisfaction profile (immunosuppressant therapy barrier scale) of once-daily tacrolimus was comparable with that of twice-daily tacrolimus (p=0.35).

CONCLUSION

Conversion from twice-daily tacrolimus to once-daily tacrolimus one month after transplantation is safe and effective.

Pharmacokinetic and CYP3A5 pharmacogenetic differences between once- and twice-daily tacrolimus from the first dosing day to 1 year after renal transplantation

Aim & patients & methods: This study investigated 24-h pharmacokinetic and CYP3A5 pharmacogenetic differences between once-daily tacrolimus (Tac-q.d.) versus twice-daily tacrolimus (Tac-b.i.d.) pretransplantation and at 1 month and 1 year post-transplantaion. Results: The dose-adjusted trough level (Cmin) and area under the blood concentration–time curve from 0 to 24 h (AUC0–24) increased twofold within 1 year post-transplantation with both formulations and the two genotypes. Good correlations were observed between the AUC0–24 and Cmin for both formulations. However, the dose-adjusted Cmin, but not dose-adjusted AUC0–24, was approximately 30% lower for Tac-q.d. than for Tac-b.i.d. Although the dose-adjusted Cmin was lower for Tac-q.d. than for Tac-b.i.d. in both genotypes, the dose-adjusted AUC0–24 was approximately 25% lower for Tac-q.d. than for Tac-b.i.d. in CYP3A5 expressers, but not in nonexpressers during the study period. Conclusion: These results suggested that the approximately 30% lower Cmin for Tac-q.d. than for Tac-b.i.d. may have achieved the same AUC0–24 with both formulations and may be associated with CYP3A5 pharmacogenomic differences, especially in CYP3A5 expressers, between Tac-b.i.d. and Tac-q.d.

Original submitted 3 May 2013; Revision submitted 11 June 2014

Pharmacokinetic study of conversion from tacrolimus twice-daily to tacrolimus once-daily in stable lung transplantation

BACKGROUND

Tacrolimus twice-daily (TAC BID) is widely used in lung transplantation (LT), but there are little data on the use of tacrolimus once-daily (TAC QD) in this population. The objective of this study was to compare the pharmacokinetics (PK) of TAC BID and TAC QD in stable, adult LT patients.

METHODS

Phase II, open-label, single-center, single-arm, prospective pilot PK study. Nineteen LT recipients with more than 6 months of postoperative follow-up and on TAC BID-based therapy were converted to TAC QD on a 1:1 (mg/mg) basis. Patients had been stable during the previous 3 months, and cystic fibrosis patients were excluded. One 24-hr PK profile was obtained on day -14 while patients were under TAC BID. A second PK profile was obtained 14 to 28 days after switching (day 0) to the same dose of TAC QD. Pre- and post-switch 24-hr PK profiles were compared.

RESULTS

Mean AUC0-24 hr was 279.8 ng mL/hr for TAC BID and 278.7 ng mL/hr for TAC QD (P=0.92). AUC0-12 hr of TAC BID was higher than the AUC12-24 hr. There was a good correlation between AUC0-24 hr and C24 for both QD (r=0.96) and BID (r=0.94) formulations. There were no differences in the adverse events occurring with the two formulations.

CONCLUSIONS

Tacrolimus bioavailability in steady state is similar in BID and QD formulations after conversion in stable LT recipients, excluding those with cystic fibrosis. Thus, our results indicate TAC BID can be safely switched to the more convenient QD formulation in this population.

A prospective cohort conversion study of twice-daily to once-daily extended-release tacrolimus: role of ethnicity

Background

Tacrolimus is a widely used calcineurin inhibitor in kidney transplantation. It is available as twice-daily Prograf® (Tac-BID) and once-daily Advagraf® (Tac-OD). Although therapeutically equivalent, some patients require dose adjustments to achieve similar trough concentrations [C₀] after conversion. Tacrolimus exposure is affected by ethnicity in the de novo setting but the role of ethnicity in determining dose requirements and adjustments after conversion is unknown.

Methods

In this study, 496 renal transplant recipients (RTRs) were prospectively converted from Tac-BID to Tac-OD, with dose adjustments targeted to achieve similar [C₀] at 12 months post-conversion. Renal function, acute rejection and Tac dose adjustments by ethnicity were analyzed.

Results

There were similar numbers of recipients from living and deceased donors. The mean transplant duration was 7 years. Of the RTRs, 60% were Caucasian and 40% were identified as belonging to an ethnic minority. There was no change in estimated renal function (eGFR) post-conversion to Tac-OD. At 12 months, 35/488 (7%) RTRs were receiving a reduced dose, 101/488 (21%) required a dose increase of which 77 (16%) were receiving at least a 30% increase in dose over baseline. The percentage of those in ethnic groups requiring a dose increase of >30% varied from 8.0% for South Asians to 27.5% for East Asians (P = 0.03), despite East Asians having a similar baseline dose of Tac-BID (3.59 mg/day) compared to the entire cohort (3.53 mg/day).

Conclusions

Ethnicity may play an important role in dosing requirements when converting from Tac-BID to Tac-OD, unrelated to baseline dose. Further investigation is required to determine the reasons for ethnic variability when patients are converted between tacrolimus preparations.

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.

A limited sampling strategy to estimate the area under the concentration-time curve of tacrolimus modified-release once-daily preparation in renal transplant recipients

OBJECTIVES

The aim of this study was to develop a limited sampling strategy to estimate the area under the concentration-time curve (AUC) of a modified-release, once-daily formulation of tacrolimus (Advagraf, Japanese trade name Graceptor) with Japanese renal transplant patients.

METHODS

Among the 43 enrolled patients, 23 patients continued to take Graceptor for 1 year. A total of 66 profiles on day 28 and day 365 from the 43 patients were randomly divided into a training group (N = 33) and a validation group (N = 33) without any overlap.

RESULTS

The prediction formula for the AUC 0-24 using the single C 12h time point gave the highest correlation with the observed AUC 0-24 (r2 = 0.9057). When 2 sampling times were used, C 0h-C 12h were the best time points for the estimation of the AUC 0-24 (AUC 0-24 = 26.8 + 8.0C 0h + 17.8C 12h, r2 = 0.9221, P < 0.0001). There was no significant difference in the prediction error for the prediction formulas with the C 0h-C 12h combination between CYP3A5 genotypes. The % mean prediction error, % mean absolute error, and % root mean squared prediction error of the prediction formula using C 0h-C 12h were 0.1%, 7.6%, and 8.8%, respectively.

CONCLUSIONS

In a hospital setting, a limited sampling strategy using C 0h-C 12h would be applicable to estimating the AUC 0-24 of tacrolimus once daily.

Treatment satisfaction in renal transplant patients taking tacrolimus once daily

BACKGROUND

Adherence to immunosuppressive therapy, which is important to prevent rejection after organ transplantation, is influenced by satisfaction of patients with their medication regimen.

OBJECTIVE

We investigated the effect of introducing a simplified medication regimen for renal transplant patients on treatment satisfaction, in particular, convenience.

METHODS

In a prospective cohort study, treatment was switched from tacrolimus twice daily to tacrolimus once daily with a simultaneous change to a once-daily formulation of other drugs when applicable. Treatment satisfaction was measured in 75 participants with the validated Treatment Satisfaction Questionnaire for Medication version II.

RESULTS

The treatment convenience score increased from a mean (SD) of 66.0 (14.5) to 78.5 (14.5) (P < 0.001). The mean (SD) daily number of medication ingestion time points diminished from 2.4 (0.7) to 1.6 (0.7) (P < 0.001), and the mean (SD) daily number of tablets decreased from 12.4 (3.3) to 9.1 (2.6) (P < 0.001). The self-reported adherence to the medication regimen increased from 79.7% to 94.6% (P < 0.001).

CONCLUSIONS

The introduction of a simplified medication regimen enabled by the use of a once-daily formulation of tacrolimus increases treatment convenience after renal transplantation. This regimen had a beneficial effect on self-reported adherence.

Conversion from Prograf to Advagraf in adolescents with stable liver transplants: comparative pharmacokinetics and 1-year follow-up

The recommended dose of Advagraf for conversion from Prograf is considered to be 1:1 on a milligram basis. However, the long-term equivalence of Prograf and Advagraf has been questioned. The relative bioavailability of Advagraf and Prograf was evaluated in a single-center, open-label study of Prograf-to-Advagraf conversion in 20 patients, ranging in age from 12 to 18 years, who had a stable liver transplant and were receiving Prograf. After the supervised administration of Prograf for 7 days, the patients were converted to Advagraf. On days 7 and 14, serial blood samples were obtained for tacrolimus determinations. The pharmacokinetic parameters were calculated with a noncompartmental approach, and the relative bioavailability of both formulations was calculated according to standard statistical methods. Polymorphisms in cytochrome P450 3A5 (rs776746), adenosine triphosphate-binding cassette B1 (rs1045642), POR*28 (rs1057868), and POR (rs2868177) were determined with standard methods. The clinical and analytical data from a 1-year follow-up period were collected for all patients 30, 90, 180, and 360 days after conversion. The mean ratios for Cmax and AUC0-24 were 96.9 (90% confidence interval = 85.37-110.19) and 100.1 (90% confidence interval = 90.8-112.1), respectively. No relationship was found between the patients' genotypes and the pharmacokinetic tacrolimus values. During the follow-up, biochemical parameters (aspartate aminotransferase, alanine aminotransferase, bilirubin, cystatin C, and creatinine) did not change significantly; 3 patients presented with relevant clinical events, but no event was considered to be related to tacrolimus. A decrease in tacrolimus blood levels and an increase in dose/level ratios were observed 3 and 6 months after conversion, but they returned to basal levels by month 12. In conclusion, conversion from Prograf to Advagraf with a 1:1 dose equivalence is appropriate as an initial guideline. Our 1-year follow-up showed a transient decrease in tacrolimus levels, so closer monitoring of tacrolimus levels may be required after conversion.

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.

Conversion from twice-daily tacrolimus capsules to once-daily extended-release tacrolimus (LCPT): a phase 2 trial of stable renal transplant recipients

BACKGROUND

LCP-Tacro is an extended-release formulation of tacrolimus designed for once-daily dosing. Phase 1 studies demonstrated greater bioavailability to twice-daily tacrolimus capsules and no new safety concerns.

METHODS

In this phase 2 study, adult stable kidney transplant patients on tacrolimus capsules (Prograf) twice-daily were converted to tacrolimus tablets (LCP-Tacro) once-daily; patients continued on LCP-Tacro once-daily for days 8 to 21; trough levels were to be maintained between 5 and 15 ng/mL; 24-hr pharmacokinetic assessments were done on days 7 (baseline pre-switch), 14, and 21.

RESULTS

Forty-seven patients completed LCP-Tacro dosing per protocol. The mean conversion ratio was 0.71. Pharmacokinetic data demonstrated consistent exposure (AUC) at the lower conversion dose. C(max) (P = 0.0001), C(max)/C(min) ratio (P < 0.001), percent fluctuation (P < 0.0001), and swing (P = 0.0004) were significantly lower and T(max) significantly (P < 0.001) longer for LCP-Tacro versus Prograf. AUC24 and C(min) correlation coefficients after 7 and 14 days of therapy were 0.86 or more, demonstrating a robust correlation between LCP-Tacro tacrolimus exposure and trough levels. There were three serious adverse events; none were related to study drug and all were resolved.

CONCLUSIONS

Stable kidney transplant patients can be safely converted from Prograf twice-daily to LCP-Tacro. The greater bioavailability of LCP-Tacro allows for once-daily dosing and similar (AUC) exposure at a dose approximately 30% less than the total daily dose of Prograf. LCP-Tacro displays flatter kinetics characterized by significantly lower peak-trough fluctuations.

Once-daily extended-release versus twice-daily standard-release tacrolimus in kidney transplant recipients: a systematic review

BACKGROUND

A simplified dosing regimen may improve drug compliance in kidney transplant recipients and long-term graft outcomes. We aimed to identify, appraise, and synthesize the current evidence comparing the relative safety and efficacy of the recently introduced daily versus standard twice-daily tacrolimus administration.

METHODS

We systematically reviewed all randomized controlled trials and observational studies that compared the outcomes of daily versus twice-daily tacrolimus formulation in kidney transplant recipients. Medline (from 1948 to July week 4 2011), Embase (1980 to 2011 week 31), the Cochrane Library (1991 to June 2011), and conference proceedings were searched without language restriction.

RESULTS

Six randomized controlled trials (n=2499) and 15 observational studies (n=2886) were included in the review. There were no significant differences in biopsy-proven acute rejection (two trials, n=1093; risk ratio [RR; confidence interval (CI)], 1.24 [0.93-1.65]; P=0.15; I=0%), patient survival (three trials, n=1156; RR [CI], 0.99 [0.97-1.02]; P=0.55; I=32%), and graft survival (three trials, n=1156; RR [CI], 0.99 [0.97-1.02]; P=0.67; I=0%) between the two formulations at 12 months. Similar results for acute rejection (five studies, n=391; RR [CI], 0.99 [0.93-1.06]; P=0.84; I=0%) and overall patient survival (two studies, n=218; RR [CI], 1.02 [0.94-1.10]; P=0.62; I=0%) were observed in observational studies.

CONCLUSIONS

Once-daily tacrolimus appears to be as effective as twice-daily tacrolimus up to 12 months after kidney transplantation.

Maintenance immunosuppression in renal transplantation

The need to maintain allograft recipients on immunosuppression is nearly universal. Immunosuppressive agents used in organ transplantation target one or more steps of the host alloimmune response, specifically processes related to CD4-positive T lymphocytes. Calcineurin-inhibitor based steroid-containing regimens have been the mainstay of maintenance immunosuppression over the last two decades. Newer agents have shown efficacy in this role in recent trials with comparable allograft and patient outcomes. These agents have permitted calcineurin-inhibitor minimization and steroid-sparing strategies in selected groups of patients.

Comparison of pharmacokinetics and pharmacogenetics of once- and twice-daily tacrolimus in the early stage after renal transplantation

BACKGROUND

This study investigated pharmacokinetic and pharmacogenetic differences between a modified-release once-daily formulation of tacrolimus (Tac-QD) and the original formulation requiring twice-daily intake (Tac-BID) in de novo renal transplant recipients.

METHODS

Forty-seven and 25 patients who received Tac-BID and Tac-QD, respectively, were enrolled. The pharmacokinetics and CYP3A5 6986A>G and ABCB1 3435C>T pharmacogenetics of each formulation were analyzed on day 28 posttransplantation.

RESULTS

The dose-adjusted trough level (C0) and area under the concentration-time curve (AUC0-24) of tacrolimus were approximately 25% lower for Tac-QD than Tac-BID. However, there was a good correlation between the AUC0-24 and C0 in the Tac-BID and Tac-QD groups (r=0.575, P<0.001; and r=0.638, P<0.001, respectively) and a similar coefficient in each regression equation. The dose-adjusted AUC0-24 was approximately 25% lower in carriers of the CYP3A*1 allele (CYP3A5 expressers), but not individuals with the CYP3A*3/*3 genotype (nonexpressers), for TAC-QD than Tac-BID. In the Tac-QD group, the interpatient variability for dose-adjusted parameters was small, and the interquatile ranges of dose-adjusted parameters differed between CYP3A5 expressers and nonexpressers and did not overlap. The ABCB1 polymorphism was not associated with any pharmacokinetic parameters of Tac-QD.

CONCLUSIONS

C0-guided monitoring may lead to similar AUC0-24 values for both formulations. However, to maintain the same AUC0-24 value, a higher dose of Tac-QD than Tac-BID may be needed, especially for CYP3A5 expressers, in the early stage posttransplantation. The narrow interindividual variability of Tac-QD pharmacokinetics and its difference between CYP3A5 expressers and nonexpressers might contribute to a dosing strategy based on CYP3A5 genotype.

Improved adherence to tacrolimus once-daily formulation in renal recipients: a randomized controlled trial using electronic monitoring

BACKGROUND

With effective agents available to prevent posttransplantation acute organ rejection, medication adherence becomes a key factor for successful treatment outcomes after renal transplantation. A once-daily, modified-release oral formulation of tacrolimus has been developed to simplify dosing and improve medication adherence.

METHODS

Adherence Measurement in Stable Renal Transplant Patients Following Conversion From Prograft to Advagraf is a randomized multicenter controlled trial to evaluate adherence between a tacrolimus once-daily regimen and a tacrolimus twice-daily regimen using an electronic monitor to document drug intake. After enrolment, all patients continued the twice-daily regimen for 3 months and then were randomized 2:1 between the two formulations and followed for 6 months. Adherence was decomposed into patients' persistence and implementation of each regimen.

RESULTS

Two hundred nineteen patients (45% male; 3±2 years after transplantation) were analyzed (145 once daily and 74 twice daily). At 6 months after randomization, 81.5% of the once-daily group and 71.9% of the twice-daily group remained persistent with the treatment (P=0.0824). Among patients who remained engaged with the regimen, 88.2% of the once-daily group and 78.8% of the twice-daily group (P=0.0009) took the prescribed number of daily doses. When the patients took the twice-daily regimen, the average percentage of missed doses was 11.7% in the morning and 14.2% in the evening (P=0.0035).

CONCLUSIONS

Regimen implementation of tacrolimus once daily is significantly superior to the twice-daily regimen. There was a residual prevalence of suboptimal adherence that will have to be countered by means other than reformulation and regimen simplification. Electronically compiled dosing histories provide detailed data on patient adherence that can be used for efficient medication management.

Long-term interleukin-2 assessment after conversion from a twice-daily to once-daily tacrolimus regimen in stable kidney recipients

Conversion to tacrolimus (Tac) to once daily (Tac-O) formulation is commonly followed by a 20% reduction in Tac trough levels in the first month. It is not associated with modifications of renal function but there is the issue of its effects on inflammatory cytokines and on subclinical rejection. The aim of our study was to evaluate long-term interleukins (IL)-2 profiles in stable renal transplant patients after Tac-O conversion. We enrolled 10 stable kidney transplant patients converted to Tac-O. Tac trough levels, serum creatinine concentrations, glomerular filtration rate using the Modification of Diet in Renal Disease formula, C-reactive protein, IL-2 levels, and clinical assessments were performed monthly for 6 months before and 12 months after conversion. Despite the significant reduction in Tac trough levels, we did not observe alterations suggestive of clinical or subclinical acute rejection.

A 39-month follow-up study to evaluate the safety and efficacy in kidney transplant recipients treated with modified-release tacrolimus (FK506E)-based immunosuppression regimen

BACKGROUND

We initially performed a study to evaluate the safety and efficacy of modified-release tacrolimus (FK506E) in a phase 3, 2-arm, 6-month, randomized, open-label, multicenter trial in Korean living donor de novo kidney transplant recipients. We then performed an extended study to evaluate the long-term safety and efficacy of a FK506E-based regimen up to 45 months posttransplantation in recipients already treated with FK506E.

METHODS

Initial study was designed as a randomized, open-label, comparative, multicenter study in de novo living donor kidney transplant recipients. The patients were randomized to an FK506E versus a control (FK506) group (1:1). Recipients who completed a 6-month FK506E treatment study were enrolled in the 39-month follow-up study. Primary end-points were patient and graft survivals at posttransplantation 45 months. Secondary end-point was the incidence of a clinical or biopsy-proven acute rejection episode between 6 and 45 months posttransplantation.

RESULTS

In the initial 6-month de novo study 124 enrolled patients were randomized into either the FK506E (n = 62) or the control group (n = 62). The incidence of an acute rejection episode was 19.4% (n = 12) in the FK506E versus 16.1% (n = 10) in the control group (P = .638). There was no mortality or graft failure among the 44 recipients enrolled in this additional 39-month follow-up study. There was 1 patient with biopsy-proven acute cellular rejection episode (2.3%) who underwent steroid pulse therapy with renal function recovery. At the time of study completion 40/44 recipients (90.9%) maintained FK506E treatment.

CONCLUSION

This 39-month study following the initial 6-month FK506E study period showed an FK506E-based immunosuppressive regimen in living donor kidney transplantation recipients to be safe and effective.