Pharmacokinetics of total and unbound prednisone and prednisolone in stable kidney transplant recipients with diabetes mellitus

Saliva monitoring of prednisolone in children with first onset steroid-sensitive nephrotic syndrome: Is it possible?

AIMS

Prednisolone is the cornerstone of treatment for idiopathic nephrotic syndrome in children, but is associated with marked side-effects. Therapeutic drug monitoring using saliva would be a patient-friendly option to monitor prednisolone treatment. To assess the feasibility of saliva monitoring, we described the pharmacokinetics (PK) of unbound prednisolone in plasma and saliva of children with first onset steroid-sensitive nephrotic syndrome (SSNS).

METHODS

Children (age 2-16 years) with SSNS participating in a randomized, placebo-controlled trial with levamisole were treated with an 18-week tapering schedule of prednisolone. Five serial samples were collected at 4 (saliva) and 8 weeks (saliva and plasma) after first onset. A nonlinear mixed-effects model was used to estimate the PK parameters of unbound prednisolone and the saliva-to-plasma ratio. Monte Carlo simulations were performed to assess the predictive performance of saliva monitoring.

RESULTS

From 39 children, 109 plasma and 275 saliva samples were available. Estimates (relative squared error) of unbound plasma clearance and volume of distribution were 93 (5%) L h-1 70 kg-1 and 158 (7%) L 70 kg-1, respectively. Typical saliva-to-plasma ratio was 1.30 (8%). Monte Carlo simulations demonstrated that on basis of 4 saliva samples and a single plasma sample unbound plasma area-under-the-concentration-time curve can be predicted within 20% imprecision in 79% of the patients compared to 87% based on 4 plasma samples.

CONCLUSION

Saliva proved to be a reliable and patient-friendly option to determine prednisolone plasma exposure in children with SSNS. This opens opportunities for further PK and pharmacodynamics studies of prednisolone in a variety of paediatric conditions.

Prednisolone pharmacokinetics after oral prednisone administration in paediatric patients with kidney transplant

AIMS

Glucocorticoids are 1 of the primary treatments in paediatric kidney transplantation. The aims of this study were: (i) to build a population pharmacokinetics (PPK) model of free prednisolone, which is the active form of prednisone, in paediatric kidney transplant recipients; (ii) to identify covariates accounting for interindividual variability (IIV) of pharmacokinetics (PK) parameters; and (iii) to investigate drug exposure-safety relationships.

METHODS

Ninety-seven samples were obtained from 39 paediatric kidney transplant recipients (aged 3.4-17.2 years) in order to investigate prednisone PPK. We selected children receiving oral prednisone as part of their immunosuppressive regimen. A PPK analysis was performed using Monolix.

RESULTS

A 1-compartment model best described prednisolone concentrations. Large IIV was observed as prednisolone was undetectable at H12 in some patients but could still be detected at H24 in others. Both bodyweight and ciclosporin cotreatment influenced the PK. The clearance (CL_U ) and volume of distribution of free prednisolone allometrically scaled to 70 kg were 27.6 L/h and 101 L. Ciclosporin cotreatment decreased CL_U by 67%. High blood pressure and new onset diabetes after transplantation were associated with daily free prednisolone exposure.

CONCLUSION

This study is the first analysis of prednisolone PPK in kidney-transplanted children. Some of the IIV in the PK parameters was explained by bodyweight and ciclosporin cotreatment. These data suggest that dose adjustment is required after identifying variability factors to optimize efficacy and limit side effects. The use of therapeutic drug monitoring in kidney-transplanted children may be useful, especially with respect to safety issues.

Evaluation of the pharmacokinetics of prednisolone in paediatric patients with acute lymphoblastic leukaemia treated according to Dutch Childhood Oncology Group protocols and its relation to treatment response

Glucocorticoids form the backbone of paediatric acute lymphoblastic leukaemia (ALL) treatment. Many studies have been performed on steroid resistance; however, few studies have addressed the relationship between dose, concentration and clinical response. The aim of the present study was to evaluate the pharmacokinetics of prednisolone in the treatment of paediatric ALL and the correlation with clinical parameters. A total of 1028 bound and unbound prednisolone plasma concentrations were available from 124 children (aged 0–18 years) with newly diagnosed ALL enrolled in the Dutch Childhood Oncology Group studies. A population pharmacokinetic model was developed and post hoc area under the curve (AUC) was tested against treatment outcome parameters. The pharmacokinetics of unbound prednisolone in plasma was best described with allometric scaling and saturable binding to proteins. Plasma protein binding decreased with age. The AUC of unbound prednisolone was not associated with any of the disease parameters or treatment outcomes. Unbound prednisolone plasma concentrations correlated with age. No effect of exposure on clinical treatment outcome parameters was observed and does not substantiate individualised dosing. Poor responders, high‐risk and relapsed patients showed a trend towards lower exposure compared to good responders. However, the group of poor responders was small and requires further research.

Prednisolone and Prednisone Pharmacokinetics in Adult Renal Transplant Recipients

BACKGROUND

Prednisolone (PL) is a standard component of most immunosuppressive protocols after solid organ transplantation (Tx). Adverse effects are frequent and well known. The aim of this study was to characterize the pharmacokinetics (PKs) of PL and prednisone (PN), including cortisol (CL) and cortisone (CN) profiles, after PL treatment in renal Tx recipients in the early post-Tx phase.

METHODS

This single-center, prospective, observational study included stable renal Tx recipients, >18 years of age, and in the early postengraftment phase. Blood samples were obtained predose and during a 24-hour dose interval [n = 26 samples per area under the curve (AUC0-24)], within the first 8 weeks post-Tx. PL, PN, CL, and CN concentrations were measured using high-performance liquid chromatography-tandem mass spectrometry.

RESULTS

In renal Tx recipients (n = 28), our results indicated a relatively high PL exposure [median, range AUC0-24 = 3821 (2232-5382) mcg h/L], paralleled by strong suppression of endogenous CL profile, demonstrated by a low CL evening-to-morning ratio [median, range 11 (3-47)%]. A negative correlation (r = -0.83) between PL AUC0-24 and morning CL levels was observed. The best single PK variable to predict PL AUC0-24 was PL C6 (r2 = 0.82). An algorithm based on 3 PK sampling time points: trough, 2, and 4 hours after PL dosing, predicted PL AUC0-24 with a low percentage prediction error (PPE = 5.2 ± 1.5%) and a good correlation of determination (r2 = 0.91). PL AUC0-24 varied 3-fold among study participants, whereas CL AUC0-24 varied by 18-fold.

CONCLUSIONS

The large interindividual variability in both PL exposure and suppression of endogenous CL implies a possible role for therapeutic drug monitoring. An abbreviated profile within the first 4 hours after PL dosing provides a good prediction of PL exposure in renal Tx recipients. The strong negative correlation between PL AUC0-24 and morning CL levels suggests a possible surrogate marker for drug exposure for further evaluation.

Estimation of Equipotent Doses for Anti-Inflammatory Effects of Prednisolone and AZD9567, an Oral Selective Nonsteroidal Glucocorticoid Receptor Modulator

AZD9567 is a potent and selective nonsteroidal oral glucocorticoid receptor modulator. It is developed as an anti-inflammatory drug with improved safety profile compared with steroids like prednisolone. Throughout the clinical development of AZD9567, dose selection and data interpretation require a method for determining doses with the same anti-inflammatory effect as prednisolone. Equipotent doses of AZD9567 and prednisolone were defined by the same average inhibition of TNFα release, a biomarker of anti-inflammatory effect, measured in a lipopolysaccharide-stimulated whole blood ex vivo assay. Based on pharmacokinetic-pharmacodynamic models, TNFα dose-response relationships for AZD9567 and prednisolone were established. A comparison of the dose-response curves enabled estimation of an equipotency relationship. Specifically, 20 mg prednisolone was estimated to be equipotent to 40 mg AZD9567 (95% confidence interval: 29-54 mg). Static concentration-response analyses showed that the relative potencies for inhibition of TNFα release of AZD9567 and prednisolone were well aligned with several other pro-inflammatory cytokines.

Development and Clinical Application of a Prednisolone/Cortisol Assay to Determine Adherence to Maintenance Oral Prednisolone in Severe Asthma

BACKGROUND

Nonadherence to oral prednisolone is an important driver of poor control in severe asthma, and its detection is warranted to guide management.

RESEARCH QUESTION

The goal of this study was to evaluate the utility of liquid chromatography and tandem mass spectrometry (LC-MS/MS) in determining the adherence status to oral prednisolone in severe asthma.

STUDY DESIGN AND METHODS

Timeline serum levels of prednisolone, cortisol, and metabolites were measured by using a validated LC-MS/MS assay following observed intake of prednisolone in patients receiving maintenance oral prednisolone. Patterns of adherence and nonadherence were determined from analysis of peak blood levels. The performance of a spot test for adherence (detectable prednisolone and suppressed cortisol) was assessed in a second cohort of patients receiving maintenance prednisolone and a control group.

RESULTS

In the prednisolone absorption test, 27 patients (mean age, 38.6 years; age range, 17-63 years; 83% female) were included. We identified adherence in 13 (48%), nonadherence in 13 (48%), and malabsorption in one (3.7%). The median [interquartile range] peak serum assays of the adherent group compared with the nonadherent group were: cortisol, 36 [39.5] vs 295 [153] nmol/L; and prednisolone, 1,810 [590] vs 1,730 [727] nmol/L. The spot test cohort included 111 patients (67 on maintenance prednisolone and 44 control subjects); the mean age was 42.4 years, and 79% were female. Nonadherence was detected in 40.3% of patients; comparison of the adherent vs nonadherent groups revealed median [interquartile range] levels for cortisol of 27 [48] nmol/L vs 211 [130] nmol/L and for prednisolone of 259 [622] nmol/L vs < 20 nmol/L, respectively. Adherent patients had higher mean BMI (38.4 ± 8.7 vs 32 ± 7.5 kg/m²; P = .03), lower median blood eosinophils (0.09 [0.31] vs 0.51 [0.53] × 10⁹/L; P < .001), and a trend toward reduced mean annual severe exacerbations (3.0 ± 2.6 vs 4.3 ± 2.4; P = .3) than nonadherent patients.

INTERPRETATION

Nonadherence to oral prednisolone is common in severe asthma and can be reliably detected in the clinic by using the LC-MS/MS assay.

Pharmacokinetics and population pharmacokinetics in pediatric oncology

Pharmacokinetic research has become increasingly important in pediatric oncology as it can have direct clinical implications and is a crucial component in individualized medicine. Population pharmacokinetics has become a popular method especially in children, due to the potential for sparse sampling, flexible sampling times, computing of heterogeneous data, and identification of variability sources. However, population pharmacokinetic reports can be complex and difficult to interpret. The aim of this article is to provide a basic explanation of population pharmacokinetics, using clinical examples from the field of pediatric oncology, to facilitate the translation of pharmacokinetic research into the daily clinic.

Alternative matrices for therapeutic drug monitoring of immunosuppressive agents using LC-MS/MS

Immunosuppressive drugs used in solid organ transplants typically have narrow therapeutic windows and high intra- and intersubject variability. To ensure satisfactory exposure, therapeutic drug monitoring (TDM) plays a pivotal role in any successful posttransplant maintenance therapy. Currently, recommendations for optimum immunosuppressant concentrations are based on blood/plasma measurements. However, they introduce many disadvantages, including poor prediction of allograft survival and toxicity, a weak correlation with drug concentrations at the site of action and the invasive nature of the sample collection. Thus, alternative matrices have been investigated. This paper reviews tandem-mass spectrometry (LC-MS/MS) methods used for the quantification of immunosuppressant drugs utilizing nonconventional matrices, namely oral fluids, fingerprick blood and intracellular and intratissue sampling. The advantages, disadvantages and clinical application of such alternative mediums are discussed. Additionally, sample extraction techniques and basic chromatography information regarding these methods are presented in tabulated form.