Pharmacokinetics of prolonged-release tacrolimus versus immediate-release tacrolimus in de novo liver transplantation: A randomized phase III substudy

Pharmacokinetics of Different Tacrolimus Formulations in the Early Post-Liver Transplant Period: A Scoping Review

Background: Tacrolimus (TAC) is the cornerstone of immunosuppression after liver transplantation (LT). TAC has a narrow therapeutic index and high inter- and intra-individual pharmacokinetic (PK) variability, requiring dose individualization. This variability is more noticeable in the early post-LT period. Objectives: This study aimed to compare the PK of different TAC formulations in the early post-LT period and describe the main PK characteristics and plasma levels obtained with each TAC formulation used. Methods: The search was conducted in MEDLINE (PubMed) and EMBASE in accordance with PRISMA-ScR guidelines. The main inclusion criteria were clinical trials and observational studies focusing on the PK parameters of TAC in LT recipients during the first month post-transplant. Results: A total of 2169 articles were identified, of which 23 met the inclusion criteria. Various PK parameters were analyzed after LT for the different TAC formulations: intravenous (iv) and oral forms, such as immediate-release (IRT), prolonged-release (PRT), and extended-release (LCPT) formulations. PK variability was higher in the initial days after LT, with different TAC exposure between formulations. IV TAC allows the rapid attainment of therapeutic levels, but it has fallen into disuse. Regarding oral formulations, IRT reaches target levels faster than PRT and LCPT. PRT and LCPT exposure seem more stable during the first month post-LT than when using IRT. Conclusions: TAC formulations exhibit relevant differences in their PK profile in the early post-LT period. PK differences might influence the dose regimen and the time to achieve PK targets. Given these variations, therapeutic drug monitoring (TDM) is essential for optimizing treatment.

Pharmacokinetic Profile of Prolonged-Release Tacrolimus When Administered via Nasogastric Tube in De Novo Liver Transplantation: A Sub-Study of the DIAMOND Trial

Background

For patients unable to swallow during the immediate post-transplant period, immunosuppressant therapy may be initiated by administering prolonged-release tacrolimus as a suspension via a nasogastric tube.

Material/Methods

In this sub-study of the DIAMOND randomized controlled trial of prolonged-release tacrolimus in de novo liver transplant recipients, we investigated the pharmacokinetic (PK) profile of prolonged-release tacrolimus when administered via nasogastric tube immediately post-transplant. PK analyses were performed on whole-blood samples collected on Day 1 of tacrolimus administration and on Day 3 post-transplantation. Endpoints included AUC_0–24, C_max, T_max, and C_min.

Results

In total, 10 patients were included in the PK sub-study. The overall mean daily dose of prolonged-release tacrolimus administered via nasogastric tube was higher on Day 1 (0.179 mg/kg) vs. Day 3 (0.140 mg/kg). Mean AUC_0–24 was higher and less variable on Day 3 vs. Day 1 (AUC_0–24 (coefficient of variation; CV): 301 (50.8) vs. 193 (94.5) ng·h/mL). Mean C_max was lower and median T_max was shorter on Day 1 vs. Day 3 (C_max (CV): 15.1 (73.9) vs. 19.1 (47.9) ng/mL; T_max (range): 2.0 (2.0–24.0) vs. 4.5 (0.5–24.0) h). A similar pattern was also observed when data were normalized for dose and body weight.

Conclusions

In contrast to previously reported findings in healthy volunteers, nasogastric administration of prolonged-release tacrolimus suspension in liver transplant patients did not substantially affect the PK profile of tacrolimus vs. intact capsules. Nasogastric administration is thus a feasible option to ensure appropriate early tacrolimus exposure in de novo liver transplant recipients.

The hepatic protective effects of tacrolimus as a rinse solution in liver transplantation: A meta-analysis

BACKGROUND

Tacrolimus was used as a rinse solution against ischaemia-reperfusion injury (IRI) in liver transplantation for years but its protective effects remain controversies.

METHODS

We conducted literature retrieval in electronic databases including MEDLINE, EMBASE and Cochrane Central to identify relevant randomized controlled trials (RCTs) investigating the effects of tacrolimus as a rinse solution in liver transplantation. Postoperative liver function, including alanine aminotransferase (ALT), aspartate aminotransferase (AST) and total bilirubin (TBIL), at postoperative day (POD) 1, 2 and 7 was extracted for pooled estimation. Forest plots were generated to calculate the differences between the groups. The I2 index statistic was used to assess heterogeneity. Publication bias was evaluated using funnel plots and Egger's test.

RESULTS

Three RCTs including 70 liver transplants were evaluated in this study. Pooled estimation revealed that rinse with tacrolimus in liver transplantation did not provide hepatic protection with respect to postoperative ALT (Test Z = 1.36; P = .175), AST (Test Z = 1.70; P = .090) or TBIL (Test Z = 0.69; P = .490). Sensitivity analysis by excluding extended donor criteria (EDC) livers showed similar results. Funnel plots and Egger's test demonstrated that there was no substantial bias.

CONCLUSION

We may tentatively conclude that tacrolimus is ineffective for amelioration of postoperative liver function as a rinse solution in liver transplantation. Nevertheless, there is great space for future research in this area, and the potential clinical value of tacrolimus needs to be further addressed. We are expecting more evidence to support our speculations.

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.

Once-daily, prolonged-release tacrolimus vs twice-daily, immediate-release tacrolimus in de novo living-donor liver transplantation: A Phase 4, randomized, open-label, comparative, single-center study

Randomized, open-label, comparative, single-center, Phase 4, 24-week study comparing pharmacokinetics (PK), safety, and efficacy of once-daily, prolonged-release tacrolimus (PR-T) with twice-daily, immediate-release tacrolimus (IR-T) in adult de novo living-donor liver transplant (LDLT) recipients in Korea. All patients received intravenous tacrolimus from Day 0 (transplantation) for 4 days and were randomized (1:1) to receive oral PR-T or IR-T from Day 5. PK profiles were taken on Days 6 and 21. Primary endpoint: area under the concentration-time curve over 24 hour (AUC_0-24 ). Predefined similarity interval for confidence intervals of ratios: 80%-125%. Secondary endpoints included: tacrolimus concentration at 24 hour (C₂₄ ), patient/graft survival, biopsy-confirmed acute rejection (BCAR), treatment-emergent adverse events (TEAEs). One-hundred patients were included (PR-T, n = 50; IR-T, n = 50). Compared with IR-T, 40% and 66% higher mean PR-T daily doses resulted in similar AUC_0-24 between formulations on Day 6 (PR-T:IR-T ratio of means 96.8%), and numerically higher AUC_0-24 with PR-T on Day 21 (128.8%), respectively. Linear relationship was similar between AUC_0-24 and C₂₄ , and formulations. No graft loss/deaths, incidence of BCAR and TEAEs similar between formulations. Higher PR-T vs IR-T doses were required to achieve comparable systemic exposure in Korean de novo LDLT recipients. PR-T was efficacious; no new safety signals were detected.