Cyclosporine and sirolimus pharmacokinetics and drug-to-drug interactions in kidney transplant recipients

Oral drug delivery with nanoparticles into the gastrointestinal mucosa

The oral route of protein and peptide drugs has been a popular method of drug delivery in recent years, although it is often a challenge to achieve effective drug release and minimize the barrier functions of the gastrointestinal tract. Gastrointestinal mucosa can capture and remove harmful substances; similarly, it can limit the absorption of drugs. Many drugs are effectively captured by the mucus and rapidly removed, making it difficult to control the release of drugs in the gastrointestinal tract. The use of drug carrier systems can overcome the mucosal barrier and significantly improve bioavailability. Nanoparticle drug carriers can protect the drug from degradation, transporting it to a predetermined location in the gastrointestinal tract to achieve more efficient and sustained drug delivery. It is becoming clearer that the characteristics of nanoparticles, such as particle size, charge, and hydrophobicity, are related to permeability of the mucosal barrier. This review focuses on the latest research progress of nanoparticles to penetrate the mucosal barrier, including the delivery methods of nanoparticles on the surface of gastrointestinal mucosa, and aims to summarize how successful oral nanoparticle delivery systems can overcome this biological barrier in the human body. In addition, the in vitro model based on gastrointestinal mucus is an important tool for drug research and development. Here, we discuss different types of drug delivery systems and their advantages and disadvantages in design and potential applications. Similarly, we reviewed and summarized various methods for evaluating oral nanoparticles in in vitro and in vivo models.

Adequacy of Initial Everolimus Dose, With and Without Calcineurin Inhibitors, in Kidney Transplant Recipients

BACKGROUND

This study investigates the adequacy of initial everolimus (EVR) dose, with and without calcineurin inhibitors (CNI), in kidney transplant recipients.

METHODS

This retrospective cohort analysis involved data from 305 kidney transplant recipients participating in 3 randomized trials receiving reduced dose cyclosporin A (CsA) combined with EVR 0.75 mg BID (CSA/EVR0.75, N = 32) or 1.5 mg BID (CSA/EVR1.5, N = 31), reduced dose tacrolimus (TAC) combined with EVR 1.5 mg BID (TAC0.05/EVR1.5, N = 83), standard dose TAC combined with EVR 1.5 mg BID (TAC0.1/EVR1.5, N = 93), and EVR 1.5 mg BID (EVR1.5, N = 66) with TAC introduction after day 5. The adequacy of the initial EVR dose, based on EVR whole blood trough between 3 and 8 ng/mL, was compared using first EVR blood concentrations obtained at day 3 after transplantation.

RESULTS

Recipient age, proportion of patients with diabetes mellitus, and proportion of grafts from living donors were different among the groups. Dose-corrected EVR concentrations were higher in patients receiving CsA than in those receiving TAC or no calcineurin inhibitors (6.7 ± 5.9 versus 5.4 ± 2.2 versus 2.4 ± 0.8 versus 2.5 ± 0.9 versus 2.2 ± 0.7, P = 0.000). No differences were observed comparing dose adjusted EVR concentrations combined with TAC or alone (P = 0.073). The proportion of patients with EVR concentration below <3 ng/mL was lower when EVR was combined with CsA (25 versus 3 versus 43 versus 33 versus 50%, P = 0.000). Later introduction of TAC did not influence EVR concentrations. There were no differences in mean CsA concentrations comparing patients receiving EVR 0.75 or 1.5 mg BID (240 ± 143 versus 213 ± 105 ng/mL). On the other hand, mean TAC concentrations were higher according to the initial TAC dose regimen (6.4 ± 3.9 versus 9.8 ± 5.9 ng/mL).

CONCLUSIONS

In de novo kidney transplant recipients, the choice of the initial dose of EVR should consider the type of calcineurin inhibitor to reach target EVR concentration within the first week in a higher proportion of patients, maximizing the efficacy/toxicity profile.

Reviewing 15 years of experience with sirolimus

Here, we review 15 years of clinical use of sirolimus in our transplant center, in context with the developing immunosuppressive strategies use worldwide. The majority of studies were conducted in de novo kidney transplant recipients, using sirolimus (SRL) in combination with calcineurin inhibitors (CNIs). We also explored steroid (ST) or CNI-sparing therapies, including CNI minimization, elimination, or conversion strategies in combination with mycophenolate (MMF/MPS). Pooled long-term outcomes were comparable with those obtained with CNI and antimetabolite combination. Surprisingly, there are still several areas that need further investigation to improve the risk/benefit profile of SRL in kidney transplantation, including pharmacokinetic/pharmacodynamic drug-to-drug interaction with cyclosporine (CsA) or tacrolimus (TAC), mechanisms of SRL-associated adverse reactions and combinations with other drugs such as belatacept and once-daily TAC, possibly leading to improved long-term adherence. These studies, along with others investigating the benefits of SRL associated lower viral infections and malignancies, are essential as we do not expect the introduction of new immunosuppressive drugs in the near future.

Pharmacokinetics and Long-Term Safety and Tolerability of Everolimus in Renal Transplant Recipients Converted From Cyclosporine

BACKGROUND

Conversion from cyclosporine (CsA) to everolimus (EVR) in kidney transplant recipients receiving mycophenolate sodium (MPS) and corticosteroids has been used to reduce CsA associated toxicities. Nevertheless, exposures produced by the initial EVR dose, the steady state pharmacokinetic and long-term safety and tolerability have not been explored in detail.

METHODS

Twenty-four stable kidney transplant recipients receiving CSA, MPS, and corticosteroids were converted from CSA to EVR. The initial EVR dose was 3 mg BID. Weekly monitoring of EVR blood concentrations was followed by a full 12 hour pharmacokinetic profile 28 days after conversion. Therapeutic drug monitoring, safety, and tolerability were analyzed during 5 years of follow-up.

RESULTS

The study population was relatively young (mean of 42 years) with a predominance of males (62%) and White (67%) recipients of kidneys from living (54%) or deceased (46%) donors. Mean time of the conversion was 61 months after transplantation. In the first 7 patients, the initial EVR dose of 3 mg BID resulted in mean EVR trough blood concentration of 14.7 ± 3.7 ng/mL at day 7. The initial EVR dose was then reduced to 2 mg BID for the following 17 patients. Four weeks after conversion, mean EVR dose was 1.7 ± 0.5 mg BID (7 patients were receiving 1 mg BID and 17 were receiving 2 mg BID) resulting in mean EVR trough blood concentration of 4.0 ± 1.4 ng/mL. Whereas mean maximum concentration (13.4 ± 2.8 versus 22.9 ± 7.4 ng/mL, P = 0.003) and mean apparent clearance (232 ± 79 versus 366 ± 173 mL/min, P = 0.016) were higher, mean area under the curve (78.2 ± 22.1 versus 102.5 ± 38.5 ng.h/mL, P = 0.067) and mean C0 (3.7 ± 1.3 versus 4.1 ± 1.5 ng/mL, P = 0.852) were no different comparing patients receiving 1 mg and 2 mg EVR BID. Mean inter-subject variability of area under the curve, trough concentration, and maximum concentration was 38%, 36%, and 38%. EVR treatment was discontinued in 29% of patients due to proteinuria (N = 2), pneumonia (N = 2), dyslipidemia (N = 2), and anemia (N = 1) and MPS dose was reduced in 58% of patients.

CONCLUSIONS

The initial 3 mg BID dose produced high EVR trough blood concentrations. The 2 mg BID dose appears to be the appropriate initial dose to provide therapeutic concentrations but still requires initial intensive therapeutic monitoring to achieve and maintain blood concentrations within the therapeutic target concentration. The combination of EVR and full dose MPS has limited long-term tolerability and safety.

Multivariable risk of developing new onset diabetes after transplant-results from a single-center study of 481 adult, primary kidney transplant recipients

BACKGROUND

Understanding the relative contributions of baseline demographics and immunosuppressive therapy on NODAT risk may help in developing preventive strategies.

METHODS

Using our prospectively followed cohort of 481 adult, primary kidney transplant recipients without pre-transplant diabetes, we determined the significant baseline predictors for the hazard rate of developing NODAT via Cox stepwise regression. The multivariable influence of first BPAR (defined as a time-dependent covariate) was also tested.

RESULTS

Median follow-up was 57 mo post-transplant; the overall percentage who developed NODAT was 22.5% (108/481). Four baseline predictors of a greater NODAT hazard rate were found (by order of selection): higher BMI (p < 0.000001), planned maintenance with SRL (p = 0.0003), non-white recipient (p = 0.0004), and older recipient age (p = 0.0004). Approximately one-half of the 106 patients in the highest demographic risk category (BMI ≥25 kg/m(2) , non-white race, and age at transplant ≥40 yr) developed NODAT; actuarial NODAT risk ranged from 10% to 30% in the lower demographic risk categories. First BPAR was also associated with significantly higher NODAT in multivariable analysis (p = 0.02)-the highly elevated NODAT rate observed during the first few months post-transplant and following first BPAR appears to demonstrate the diabetogenic effect of using high-dose (intravenous) corticosteroids.

CONCLUSIONS

The disturbingly high NODAT rate found among patients having multiple demographic risk factors is still an important problem that awaits a better solution.

Pharmacokinetics of Cyclosporine A in Chinese heart transplant recipients

AIM

To determine the steady state concentration and the pharmacokinetics of Cyclosporine A (CsA) in heart transplant recipients.

METHODS

A single dose of 100 mg CsA capsules twice daily was given to five heart transplant recipients of steady state. The concentrations of CsA in plasma were determined by streptavidin peroxidase fluorescent polarization immunoassay.

RESULTS

The main pharmacokinetic parameters of CsA were as follows: t(max) (1.60 ± 0.55) h, ρmax(951.60 ± 229.20) μg.L-1, t1/2(6.53 ± 2.40) h, and AUC0 -t(5162.10 ± 1355.01) μg.h.L-1.

CONCLUSION

The study obtained the steady state pharmacokinetic parameters of CsA in Chinese heart transplant recipients.

Factors that affect concentrations of cyclosporine during the induction period of kidney transplantation: multivariate analysis

OBJECTIVE

The pharmacokinetics of cyclosporine (CsA) depend on numerous factors over the transplantation course. The aim of this study was to evaluate the impact of several clinical variables on CsA concentrations during the induction period after kidney transplantation.

METHODS

Potential variables were contrasted with CsA concentrations at 2 hours postdose (C(2)) and with the area under the concentration curve of CsA (AUC) at days 3 and 10 after transplantation. Evaluated variables were: recipient age, gender, body mass index (BMI), type/duration of previous dialysis, pretransplant serum creatinine (sCr), donor type, CsA dose, cold ischemia time, reduction of sCr, and use of other immunosuppressive drugs.

RESULTS

This series included 112 patients who displayed an average age of 43 ± 13 years, including 62 men and 31 recipients of living donor organs. The induction dose of CsA was 8.36 ± 1.53 mg/kg. On day 3, the C(2) was related to the reduction of sCr (P = 0.034) and to the BMI (P = 0.033). There was an inverse correlation with pretransplant sCr (P = 0.012). The AUC correlated with BMI (P = 0.027) and living donor category (P = .002). Patients receiving rapamycin or a locally procured kidney showed a trend toward higher AUC values. On day 10, the CsA dose and use of rapamycin showed a trend to higher values of C(2); the AUC was related to the CsA dose (P = .034). None of the other variables showed significant effects. Analysis between variables showed that time on dialysis correlated with the pretransplant sCr (P = .002) and that the CsA dose was negatively associated with BMI (P = .009).

CONCLUSION

Pretransplant sCr, BMI, living donor kidney category, better functional recovery, and the dose of CsA were predictors of CsA concentrations of clinical interest during this induction period. The effect of BMI was not related to higher doses of CsA.

Cyclosporin A--a review on fermentative production, downstream processing and pharmacological applications

In present times, the immunosuppressants have gained considerable importance in the world market. Cyclosporin A (CyA) is a cyclic undecapeptide with a variety of biological activities including immunosuppressive, anti-inflammatory, antifungal and antiparasitic properties. CyA is produced by various types of fermentation techniques using Tolypocladium inflatum. In the present review, we discuss the biosynthetic pathway, fermentative production, downstream processing and pharmacological activities of CyA.