Large within-day variation in cyclosporine absorption: circadian variation or food effect?

Effects of diurnal variation of bile acids by meal on cyclosporine A absorption

BACKGROUND

Stabilizing blood levels with microemulsified cyclosporine A (CsA), administered in many pediatric kidney diseases, is important for effective immunosuppression and reduced nephrotoxicity. CsA is affected by total bile acids (TBAs); however, no reports have simultaneously measured both. We aimed to elucidate the hypothesized relationship between TBA levels and diurnal variation in CsA in children.

METHODS

We retrospectively reviewed the medical records of children who were taking oral CsA for the treatment of kidney diseases between January 2016 and July 2021. They consumed four balanced meals and snacks during the day. CsA and TBA were measured twice, in pairs, before and at 0.5, 1, 1.5, 2, 3, and 4 h after oral administration in the morning and evening, and the four-h area under curve (AUC)_0-4 of CsA and trough-to-peak ratio (TPR) of TBA were compared.

RESULTS

Fifty-eight pairs were measured in total; 12 children had idiopathic nephrotic syndrome and 4 children had immunoglobulin A vasculitis with nephritis. The median age at measurement was 7.5 years and the dose of CsA was 3.8 mg/kg/day. The AUC_0-4 (ng·h/mL) was significantly lower in the evening than in the morning (1,669 vs. 1,451, P < 0.001). The TPR of TBA was significantly higher in the evening than in the morning (0.14 vs. 0.25, P < 0.001).

CONCLUSIONS

The low AUC_0-4 and slow TBA secretion observed in the evening may be due to pediatric-specific dietary rhythms; thus, snack timing should be considered in children for stabilizing CsA levels.

The Many Faces of Calcineurin Inhibitor Toxicity-What the FK?

Calcineurin inhibitors (CNIs) are both the savior and Achilles' heel of kidney transplantation. Although CNIs have significantly reduced rates of acute rejection, their numerous toxicities can plague kidney transplant recipients. By 10 years, virtually all allografts will have evidence of CNI nephrotoxicity. CNIs have been strongly associated with hypertension, dyslipidemia, and new onset of diabetes after transplantation-significantly contributing to cardiovascular risk in the kidney transplant recipient. Multiple electrolyte derangements including hyperkalemia, hypomagnesemia, hypercalciuria, metabolic acidosis, and hyperuricemia may be challenging to manage for the clinician. Finally, CNI-associated tremor, gingival hyperplasia, and defects in hair growth can have a significant impact on the transplant recipient's quality of life. In this review, the authors briefly discuss the pharmacokinetics of CNI and discuss the numerous clinically relevant toxicities of commonly used CNIs, cyclosporine and tacrolimus.

Cyclosporine use in hematopoietic stem cell transplantation: pharmacokinetic approach

Cyclosporine is one of the most vital agents in the process of successful allogeneic hematopoietic stem cell transplantation. Despite a long history and worldwide extent of cyclosporine use for prevention of graft versus host disease, currently there are lots of uncertainties about its optimal method of application to reach the best clinical outcome. A major portion of this problem stems from complicated cyclosporine pharmacokinetics. Study of cyclosporine pharmacokinetic behavior can significantly help recognition of its effectiveness and consequently, optimization of dosing, administration, monitoring and management of adverse effects. In this review, highly accredited but sparse scientific data are gathered in order to provide a better insight for preparation of practice guidelines and directing future studies for allogeneic hematopoietic cell recipients.

Calcineurin inhibitors differentially alter the circadian rhythm of T-cell functionality in transplant recipients

Background

Graft survival in transplant recipients depends on pharmacokinetics and on individual susceptibility towards immunosuppressive drugs. Nevertheless, pharmacodynamic changes in T-cell functionality in response to drugs and in relation to pharmacokinetics are poorly characterized. We therefore investigated the immunosuppressive effect of calcineurin inhibitors and steroids on general T-cell functionality after polyclonal stimulation of whole blood samples.

Methods

General T-cell functionality in the absence or presence of immunosuppressive drugs was determined in vitro directly from whole blood based on cytokine induction after stimulation with the polyclonal stimulus Staphylococcus aureus enterotoxin B. In addition, diurnal changes in leukocyte and lymphocyte subsets, and on T-cell function after intake of immunosuppressive drugs were analyzed in 19 patients during one day and compared to respective kinetics in six immunocompetent controls. Statistical analysis was performed using non-parametric and parametric tests.

Results

Susceptibility towards calcineurin inhibitors showed interindividual differences. When combined with steroids, tacrolimus led to more pronounced increase in the inhibitory activity as compared to cyclosporine A. While circadian alterations in leukocyte subpopulations and T-cell function in controls were related to endogenous cortisol levels, T-cell functionality in transplant recipients decreased after intake of the morning medication, which was more pronounced in patients with higher drug-dosages. Interestingly, calcineurin inhibitors differentially affected circadian rhythm of T-cell function, as patients on cyclosporine A showed a biphasic decrease in T-cell reactivity after drug-intake in the morning and evening, whereas T-cell reactivity in patients on tacrolimus remained rather stable.

Conclusions

The whole blood assay allows assessment of the inhibitory activity of immunosuppressive drugs in clinically relevant concentrations. Circadian alterations in T-cell function are determined by dose and type of immunosuppressive drugs and show distinct differences between cyclosporine A and tacrolimus. In future these findings may have practical implications to estimate the net immunosuppressive effect of a given drug-regimen that daily acts in an individual patient, and may contribute to individualize immunosuppression.