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.

Assessment of adherence to corticosteroids in asthma by drug monitoring or fractional exhaled nitric oxide: A literature review.

BACKGROUND: Although the efficacy of corticosteroid treatment in controlling asthma is widely accepted, its effectiveness is undermined by poor adherence. However, the optimal method for measuring adherence to asthma therapy remains unclear. OBJECTIVE: To perform a review of the literature reporting biological, objective methods for assessing adherence to inhaled or oral corticosteroids in asthma; we included studies reporting direct measurement of exogenous corticosteroids in blood, or the effect of adherence on exhaled nitric oxide. DESIGN: We searched three databases MEDLINE (using both PubMed and Ovid), the Cumulative Index of Nursing and Allied Health Literature (CINAHL) and Web of Science for articles published between January 1975 and July 2020. Quality of the studies was assessed using the National Institute of Health checklist. RESULTS: From 2850 screened articles, 26 fulfilled the inclusion criteria. Measurement of blood prednisolone with or without cortisol was used in eight studies as a measure of oral corticosteroid adherence, and fractional exhaled nitric oxide (FeNO) in 17 studies for inhaled corticosteroid adherence. Inhaled corticosteroids were measured directly in the blood in one study. By direct measurement of drug levels in the blood, adherence rates to oral corticosteroids ranged from 47% to 92%, although the performance and timing of the test were often not known, making interpretation of findings and serum prednisolone concentrations difficult. FeNO is generally lower in adherent than non-adherent patients, but no absolute cut-off can be proposed based on the available data. However, a fall in FeNO following supervised inhaled corticosteroid dosing could indicate previous poor adherence. CONCLUSIONS AND CLINICAL RELEVANCE: Despite prednisolone and cortisol levels commonly being used as adherence markers in clinical practice, further work is required to assess the influence of the dose and timing on blood levels. The promising findings of FeNO suppression testing should be explored in further prospective studies.

Physiologically Based Pharmacokinetic Modeling Involving Nonlinear Plasma and Tissue Binding: Application to Prednisolone and Prednisone in Rats.

The pharmacokinetics (PK) of prednisolone (PNL) exhibit nonlinearity related to plasma protein binding, tissue binding, metabolic interconversion with prednisone (PN), and renal elimination. Blood and 11 tissues were collected from male Wistar rats after steady-state (SS) infusion and after subcutaneous boluses of 50 mg/kg of PNL. Concentrations of PNL and PN were measured by liquid chromatography-tandem mass spectrometry. Plasma and tissue profiles were described using a complex physiologically based pharmacokinetics (PBPK) model. Concentrations of PN and PNL were in rapid equilibrium in plasma and tissues. The tissue partition coefficients (K p ) of PNL calculated from most subcutaneously dosed tissue and plasma areas were similar to SS infusion and in silico values. The blood-to-plasma ratio of PNL was 0.71 with similar red blood cell and unbound-plasma concentrations. Plasma protein binding (60%-90%) was related to corticosteroid-binding globulin (CBG) saturation. Tissue distribution was nonlinear. The equilibrium dissociation constant (K d ) of PNL shared by all tissues was 3.01 ng/ml, with the highest binding in muscle, followed by liver, heart, intestine, and bone and the lowest binding in skin, spleen, fat, kidney, lung, and brain. Fat and bone distribution assumed access only to interstitial space. Brain PNL concentrations (K p = 0.05) were low owing to presumed P-glycoprotein-mediated efflux. Clearances of CBG-free PNL were 1789 from liver and 191.2 ml/h from kidney. The PN/PNL ratio was nonlinear for plasma, spleen, heart, intestine, bone, fat, and linear for the remaining tissues. Our PBPK model with multiple complexities well described the PK profiles of PNL and PN in blood, plasma, and diverse tissues. SIGNIFICANCE STATEMENT: Because steroids, such as prednisolone and prednisone, have similar and complex pharmacokinetics properties in various species, receptors in most tissues, and multiple therapeutic and adverse actions, this physiologically based pharmacokinetics (PBPK) model may provide greater insights into the pharmacodynamic complexities of corticosteroids. The complex properties of these compounds require innovative PBPK modeling approaches that may be instructive for other therapeutic agents.

Serum prednisolone levels as a marker of oral corticosteroid adherence in severe asthma.

BACKGROUND: Severe asthma is a complex heterogeneous disease typically requiring advanced therapies. Underlying the treatment of all asthma, however, is the consistent recommendation across international guidelines to ensure that adherence to therapy is adequate. Currently, there is no consensus on an objective marker of adherence. METHODS: We performed a prospective observational study of 17 participants taking oral prednisolone using serum prednisolone levels as a marker of adherence, and sputum eosinophilia as a marker of control of type 2 airway inflammation. Based on these biomarkers, we classified participants into a non-adherent and an adherent cohort, and further stratified by the presence of ongoing sputum eosinophilia. RESULTS: We identified 3 non-adherent participants and 14 who were adherent, based on their serum prednisolone levels. Stratification using sputum eosinophil counts identified one participant as having ongoing sputum eosinophilia in the setting of non-adherence, while six were identified as steroid resistant with ongoing sputum eosinophilia despite adherence to oral prednisolone therapy. CONCLUSION: Serum prednisolone can be used an objective marker of adherence in those patients with severe asthma taking daily oral prednisolone. In combination with sputum eosinophil counts, a steroid resistant cohort can be distinguished from one with ongoing inflammation in the setting of non-adherence. This information can then be used by clinicians to differentiate the optimal next steps for treatment in these specific populations. TRIAL REGISTRATION: Participants were recruited as part of the Markers of Inflammation in the Management of Severe Asthma (MIMOSA) study, trial registration ACTRN12616001015437 , 02 August 2016.

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.

Do dried blood spots (DBS) have the potential to support result management processes in routine sports drug testing?

Dried blood spots (DBS) have been considered as complementary matrix in sports drug testing for many years. Especially concerning substances prohibited in-competition only, the added value of DBS collected concomitantly with routine doping control urine samples has been debated, and an increasing potential of DBS has been discussed in the scientific literature. To which extent and under which prerequisites DBS can contribute to enhanced anti-doping efforts is currently evaluated. As a proof-of-principle, two analytical applications, one targeting cocaine/benzoyl ecgonine and the other prednisone/prednisolone, are presented in this perspective to indicate potential added value but also presently existing limitations of the DBS approach.

Prednisone and Its Active Metabolite Prednisolone Attenuate Lipid Accumulation in Macrophages.

BACKGROUND: Synthetic forms of glucocorticoids (GCs; eg, prednisone, prednisolone) are anti-inflammatory drugs that are widely used in clinical practice. The role of GCs in cardiovascular diseases, including atherosclerosis, is highly controversial, and their impact on macrophage foam cell formation is still unknown. We investigated the effects of prednisone and prednisolone on macrophage oxidative stress and lipid metabolism. METHODS AND RESULTS: C57BL/6 mice were intraperitoneally injected with prednisone or prednisolone (5 mg/kg) for 4 weeks, followed by lipid metabolism analyses in the aorta and peritoneal macrophages. We also analyzed the effect of serum samples obtained from 9 healthy human volunteers before and after oral administration of prednisone (20 mg for 5 days) on J774A.1 macrophage atherogenicity. Finally, J774A.1 macrophages, human monocyte-derived macrophages, and fibroblasts were incubated with increasing concentrations (0-200 ng/mL) of prednisone or prednisolone, followed by determination of cellular oxidative status, and triglyceride and cholesterol metabolism. Prednisone and prednisolone treatment resulted in a significant reduction in triglyceride and cholesterol accumulation in macrophages, as observed in vivo, ex vivo, and in vitro. These effects were associated with GCs' inhibitory effect on triglyceride- and cholesterol-biosynthesis rates, through downregulation of diacylglycerol acyltransferase 1 and HMG-CoA reductase expression. Glucocorticoid-induced reduction of cellular lipid accumulation was mediated by the GC receptors on the macrophages, because the GC-receptor antagonist (RU486) abolished these effects. In fibroblasts, unlike macrophages, GCs showed no effects. CONCLUSION: Prednisone and prednisolone exhibit antiatherogenic activity by protecting macrophages from lipid accumulation and foam cell formation.

Prednisolone Concentrations in Plasma (Total and Unbound) and Saliva of Adult Kidney Transplant Recipients.

BACKGROUND: Prednisolone displays significant pharmacokinetic variability and exposure-outcome relationships in renal transplant recipients, suggesting a role for drug monitoring in some scenarios. It is highly protein-bound, and the free form is pharmacologically active but cumbersome to measure. Saliva concentrations might reflect free plasma prednisolone and present an alternative measurement. The aim of this study was to examine the correlation between total and free plasma and saliva prednisolone in adult renal transplant recipients. METHODS: Total and free plasma and saliva prednisolone concentrations were measured in 20 patients receiving oral prednisolone 1-2 months after transplant, between pre-dose and 12 hours post-dose. Prednisolone was determined using high-performance liquid chromatography mass spectrometric detection. The Pearson coefficient was used to assess the association between plasma and salivary prednisolone concentrations and area under the concentration-time curves (AUC0-12). RESULTS: When considering all time points, the total and free plasma prednisolone concentrations correlated well (r = 0.81), but there was poor correlation between saliva and free (r = 0.003) and total (r = 0.01) plasma concentrations. When concentrations before the maximum free prednisolone plasma value were excluded, the correlation between free plasma and saliva concentrations improved (r = 0.57). There was a moderate correlation between free and total plasma prednisolone AUC0-12 (r = 0.62) using all time points, but a poor correlation between free and total plasma prednisolone AUC0-12 and saliva AUC0-12 (r = 0.07; r = 0.17). CONCLUSIONS: Total and free plasma prednisolone measurements correlated poorly with saliva measurements; however, correlation improved when concentrations early in the dosing interval were excluded.

Effect of hyperhydration on the pharmacokinetics and detection of orally administered budesonide in doping control analysis.

The aim of the present study was to investigate if hyperhydration could influence the excretion and subsequent detection of budesonide (BDS) and its main metabolites (6ß-hydroxy-budesonide and 16α-hydroxy-prednisolone) during doping control analysis by leading to concentrations below the WADA reporting level (30 ng/mL). The influence of hyperhydration on the plasma and urinary pharmacokinetic (PK) profiles of BDS and metabolites was also examined. Seven healthy physically active non-smoking Caucasian males participated in a 15-day clinical study. BDS was administered orally at a single dose of 9 mg on Days 1, 7, and 13. Hyperhydration was applied in the morning on two consecutive days, that is, 0 and 24 hours after first fluid ingestion. Water and a commercial sports drink were used as hyperhydration agents (20 mL/kg body weight). Results showed no significant difference (P > 0.05, 95% CI) on plasma or urinary PK parameters under hyperhydration conditions for all the analytes. However, significant differences (P < 0.05, 95% CI) due to hyperhydration were observed on the urinary concentrations of BDS and metabolites. To compensate the dilution effect due to hyperhydration, different adjustment methods were applied based on specific gravity, urinary flow rate, and creatinine. All the applied methods were able to adjust the concentration values close to the baseline ones for each analyte; however, specific gravity was the optimum method in terms of effectiveness and practicability. Furthermore, no masking of the detection sensitivity of BDS or its metabolites was observed due to hyperhydration either in plasma or urine samples.

UHPLC assisted simultaneous separation of apigenin and prednisolone and its application in the pharmacokinetics of apigenin.

A new ultra-high performance liquid chromatography-mass spectrometry-mass spectrometry (UHPLC-MS/MS) system has been formulated for the resolution of closely related drugs apigenin (API, a bioflavinoid) and prednisolone (PRD) from their mixture. This developed method comprised of a "BEH™ C18 column (50 mm × 2.1 mm, 1.7 µm)" using acetonitrile and 0.1% formic acid (35:65 v/v) at a supply rate of 0.25 mL·min-1 as eluent. It was found that selected eluent provided short run time (≤2.5 min) as well as better peak symmetry. Satisfactory values of chromatographic parameters such as resolution (Rs = 2.5), capacity factor (k; 13.6 and 23.4 for API and PRD respectively, selectivity (α = 1.72) and number of theoretical plates (N; 3789 and 42,435 for API and PRD respectively) indicate the efficiency of the developed method. The obtained separation was then exploited for the detection and measurement of API in rat plasma sample by means of PRD as an "internal standard" (IS). The eluted compounds in plasma were identified by tandem mass spectrometry by means of tandem quadrupole (TQ) detector ("Waters Corp., Milford, MA") fortified with an "electrospray ionisation (ESI)" source functioning in positive ionization mode. The determination of API in plasma was accomplished by means of "multiple reactions monitoring (MRM)" mode. Assortment of "ionization pairs" (m/z) was displayed in the following manner: API: 270.99 → 152.9 ("cone voltage" 57 V, "collision energy" 34 V), PRD: 403.172 → 385.224 ("cone voltage" 42 V, "collision energy" 13 V). The calibration curves followed linearity in concentration range of 05-1000 ng mL-1 with limit of detection "LOD" and limit of quantification "LOQ" of 7.30 and 22.77 ng mL-1, respectively. The developed method was validated taking into consideration various test conditions and satisfactory values of various parameters such as linearity (r2 ±â€¯SD = 0.9995 ±â€¯0.0005), interday accuracy (88-120%), interday precision % RSD = 3.30-13.65% whereas intraday accuracy (91-118%) intraday precision % RSD = 1.18-5.83) indicated its validity. The validation outcomes fulfilled the standards of united states food and drug administration "USFDA" in addition Scientific Working Group for Forensic Toxicology "SWGTOX" guiding principles and were not beyond the tolerable constraint. The process developed in plasma was efficaciously harnessed in the pharmacokinetic investigation of various formulations of API after oral administration in rats.

Body weight, blood pressure, and systemic changes following low-dosage prednisolone administration in dogs.

OBJECTIVE To investigate systemic changes following low-dosage prednisolone administration in dogs. ANIMALS 4 healthy purpose-bred adult male Beagles. PROCEDURES Dogs were administered prednisolone PO at a dosage of 2 mg/kg/d for 2 weeks, 1 mg/kg/d for 4 weeks, and 0.5 mg/kg/d for 3 weeks. Body weight, blood pressure, hepatic size and echogenicity, percentage of vacuolated hepatocytes, serum hepatic enzyme activities and glucose concentration, adrenal gland size, and pancreatic echogenicity were evaluated weekly for 9 weeks. RESULTS The only significant change identified was an increase in hepatic echogenicity, assessed by measuring liver-kidney contrast on ultrasonographic images. Increases in hepatic size and percentage of vacuolated hepatocytes were identified, but values did not differ from baseline values. Similarly, serum hepatic enzyme activities increased, but changes were mild and not significantly different from baseline values. Body weight, pancreatic echogenicity, and serum glucose concentration did not show noticeable changes. Mild systemic hypertension was seen, but blood pressure was not significantly different from the baseline value. Similarly, adrenal gland size steadily decreased during the first 6 weeks and increased again after the prednisolone dosage was decreased to 0.5 mg/kg/d. However, mean adrenal gland size was not significantly different from the baseline value at any time. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that in dogs, administration of prednisolone at a low dosage was associated with minimal systemic effects.

Exploratory study of total and free prednisolone plasma exposure and cushingoid appearance, quality of life and biochemical toxicity in adult male kidney transplant recipients.

BACKGROUND AND OBJECTIVE: Long-term adverse effects of oral glucocorticoids are frequent and serious. Large between-patient variability in the pharmacokinetics of prednisolone might explain why drug dose is a poor predictor of drug-related toxicity. The aim of the study was to investigate relationships between prednisolone exposure and adverse effects. METHODS: Male kidney transplant recipients were recruited for serial blood sampling and assessment of glucocorticoid-related adverse effects including dyslipidaemia, abnormal body fat distribution, Cushingoid appearance and impaired quality of life. Total and free prednisolone plasma concentrations were determined using ultra-high-performance liquid chromatography with tandem mass spectrometric detection. Prednisolone exposure was estimated using a limited sampling strategy. RESULTS: Fifty-six patients were recruited. Patients had a mean age of 54 years and median time post-transplantation of 75 months. Median prednisolone dose was 5 mg. Mean area under the plasma concentration-time curve was 2390 nmol h/L (±580) (SD) and 175 nmol h/L (±78) for total and free prednisolone, respectively. Waist to upper arm circumference ratio was positively associated with free prednisolone plasma exposure with a Spearman correlation coefficient of 0.30 (p value 0.02). The correlation coefficient was 0.24 (p value 0.08) for neck to upper arm circumference ratio and free prednisolone plasma exposure. The clinical Cushingoid phenotype as determined by the Visual Assessment of Cushing's Severity (VACS) score was associated with a reduced score relating to physical functioning on the SF-12, but there was no significant relationship between free prednisolone plasma exposure and quality-of-life scores. Lipid levels and haemoglobin A1c (HbA1c) were not associated with total or free prednisolone exposure. CONCLUSIONS: There is a positive correlation between free prednisolone plasma exposure and waist to upper arm circumference ratio in adult male kidney transplant recipients on low maintenance prednisolone doses. There is no significant association between total or free prednisolone plasma exposure and plasma glucose and lipid levels in the low prednisolone dose range.

Quantitative LC-MS determination of liposomal encapsulated prednisolone phosphate and non-encapsulated prednisolone concentrations in murine whole blood and liver tissue.

The underlying pharmacokinetic profile of liposomal drug delivery systems is not yet fully known. This is primarily due to a lack of suitable quantitative bioanalytical methodology to simultaneously determine separate liposomal-encapsulated and non-encapsulated drug tissue concentrations in complex biological samples. Here, an LC-MS method was developed which enables the simultaneous quantification of separate liposomal-encapsulated prednisolone phosphate and non-encapsulated prednisolone concentrations in whole blood and liver tissue. Liquid chromatography, negative electrospray ionization and Orbitrap-MS analysis allowed highly accurate and sensitive detection of prednisolone phosphate (PP) and prednisolone (P) in complex matrix. Using dexamethasone phosphate and dexamethasone as internal standards, the quantitative LC-MS method was optimized and validated for high selectivity, sensitivity and quantitative accuracy of PP and P from liposomes. The lower limits of quantitation were 0.99µmol/L blood and 0.53nmol/g liver for PP, and 229nmol/L blood and 0.514nmol/g liver for P. Quantitative accuracies of 84-118% were observed. The intra-run precision was ≤11%. Application of this new LC-MS method will yield the first liposomal pharmacokinetic profile showing accurate encapsulated and non-encapsulated drug tissue concentrations separately. This is also the first quantitative LC-MS method for the simultaneous quantification of the prodrug PP and its parent drug P in whole blood and liver tissue samples.

Exposure-effect relationship of mycophenolic acid and prednisolone in adult patients with lupus nephritis.

AIMS: The aim was to examine relationships between total and unbound mycophenolic acid (MPA) and prednisolone exposure and clinical outcomes in patients with lupus nephritis. METHODS: Six blood samples were drawn pre- and at 1, 2, 4, 6 and 8 h post-dose and total and unbound MPA and prednisolone pre-dose (C0 ), maximum concentration (Cmax ) and area under the concentration-time curve (AUC) were determined using non-compartmental analysis in 25 patients. The analyses evaluated drug exposures in relation to treatment response since starting MPA and drug-related adverse events. RESULTS: Dose-normalized AUC varied 10-, 8-, 7- and 19-fold for total MPA, unbound MPA, total prednisolone and unbound prednisolone, respectively. Median values (95% CI) of total MPA AUC(0,8 h) (21.5 [15.0, 42.0] vs. 11.2 [4.8, 30.0] mg l(-1) h, P= 0.048) and Cmax (11.9 [6.7, 26.3] vs. 6.1 [1.6, 9.2] mg l(-1) , P = 0.016) were significantly higher in responders than non-responders. Anaemia was significantly associated with higher total (37.8 [14.1, 77.5] vs. 18.5 [11.7, 32.7] mg l(-1) h, P = 0.038) and unbound MPA AUC(0,12 h) (751 [214, 830] vs. 227 [151, 389] mg l(-1) h, P = 0.004). Unbound prednisolone AUC(0,24 h) was significantly higher in patients with Cushingoid appearance (unbound: 1372 [1242, 1774] vs. 846 [528, 1049] nmol l(-1) h, P = 0.019) than in those without. Poorer treatment response was observed in patients with lowest tertile exposure to both total MPA and prednisolone as compared with patients with middle and higher tertile exposure (17% vs. 74%, P = 0.023). CONCLUSIONS: This study suggests a potential role for therapeutic drug monitoring in individualizing immunosuppressant therapy in patients with lupus nephritis.

Plasma and ocular prednisolone disposition after oral treatment in cats.

OBJECTIVE: To evaluate the plasma and aqueous humor disposition of prednisolone after oral administration in cats. METHODS: Six cats were administered with a single oral dose of prednisolone (10 mg). Blood and aqueous humor samples were serially collected after drug administration. Prednisolone concentrations in plasma and aqueous humor were measured at 0.25, 0.5, 1.0, 1.5, 2.0, 3.0, 4.0, and 5.0 h after administration by a high-performance liquid chromatographic analytical method developed and validated for this purpose. RESULTS: Mean ± standard error (SE) of maximum plasma prednisolone concentration (300.8 ± 67.3 ng/mL) was reached at 1 h after administration. Prednisolone was distributed to the aqueous humor reaching a mean peak concentration of 100.9 ± 25.5 ng/mL at 1.25 h after administration. The mean ± SE systemic and aqueous humor exposure (AUC) was 553.3 ± 120.0 ng h/mL and 378.8 ± 64.9 ng h/mL, respectively. A high AUC(aqueous humor)/AUC(plasma) ratio was observed (0.68 ± 0.13). The mean half-life time of elimination in plasma and aqueous humor was 0.87 ± 0.16 h and 2.25 ± 0.44 h, respectively. CLINICAL SIGNIFICANCE: The observed high ratio between aqueous humor and plasma prednisolone concentrations indicates that extensive penetration of prednisolone to the anterior segment of the eye may occur. This is the first step that contributes to the optimization of the pharmacological therapeutics for the clinical treatment of uveitis.

Monitoring prednisolone and prednisone in saliva: a population pharmacokinetic approach in healthy volunteers.

BACKGROUND: Prednisolone (PLN) is a widely used corticosteroid in a variety of immune-mediated diseases. Treatment regimes generally consist of empirically derived treatment doses, whereas therapeutic response among patients is highly variable. Drug monitoring of serum PLN levels might support a more rational approach to dose selection, yet is invasive and laborious. In analogy to cortisol, salivary PLN may offer a good alternative for serum PLN, being a representative approximation of free serum PLN. The aims of this study were to evaluate the correlation between free serum and salivary PLN levels and to quantify this relationship within a population pharmacokinetic model. METHODS: PLN and prednisone (PN) concentrations were measured in 396 samples from 19 healthy volunteers after oral ingestion of 80 mg PLN. Measurements in serum, ultrafiltrate, and saliva were performed with a recently validated liquid chromatography tandem mass spectrometry method. Population pharmacokinetic analysis was performed with nonlinear mixed effect modeling using NONMEM. RESULTS: Salivary PLN levels correlated well with free serum PLN levels (r = 0.931, P < 0.01). A weaker correlation was found for PN (r = 0.318, P < 0.01), which may be explained by the finding that salivary PN levels mainly seemed to consist of PLN enzymatically converted to PN. Total and free serum PLN concentrations decreased over time after drug administration and showed a nonlinear mutual relationship, consistent with concentration-dependent protein binding. Modeled PLN pharmacokinetics corresponded with previous reports. Low to moderate interindividual variability was found for V/F and CL/F (coefficients of variation were 13.8% and 14.6%, respectively). Free and salivary PLN showed a nonlinear relationship with total PLN. An equation predicting free serum levels from salivary levels was successfully derived from the data. CONCLUSIONS: This study is the first to describe the relationship between salivary and (free) serum PLN using a population pharmacokinetic model. Salivary PLN was found to be a reliable predictor of free and total serum PLN in healthy volunteers. The results of this study encourage further exploration of the use of saliva as a noninvasive and feasible method for drug monitoring of PLN.

Potential of treatment-specific protein biomarker profiles for detection of hormone abuse in cattle.

Targeted protein biomarker profiling is suggested as a fast screening approach for detection of illegal hormone treatment in meat production. The advantage of using biomarkers is that they mark the biological response and, thus, are responsive to a panel of substances with similar effects. In a preliminary feasibility study, a 4-plex protein biomarker flow cytometric immunoassay (FCIA) previously developed for the detection of recombinant bovine somatotropin (rbST) was applied to cattle treated with steroids, such as estradiol, dexamethasone, and prednisolone. Each treatment resulted in a specific plasma biomarker profile for insulin-like growth factor-1 (IGF-1), IGF binding protein 2, osteocalcin, and anti-rbST antibodies, which could be distinguished from the profile of untreated animals. In summary, the 4-plex biomarker FCIA is, apart from rbST, also capable of detecting treatment with other growth-promoting agents and therefore clearly shows the potential of biomarker profiling as a screening method in veterinary control. It is proposed to perform additional validation studies covering high numbers of treated and untreated animals to support inclusion or adaptation of protein biomarker approaches in future monitoring regulations.

Influence of body condition on plasma prednisolone and prednisone concentrations in clinically healthy cats after single oral dose administration.

Influence of body condition (over-conditioned vs. normal-conditioned) on plasma glucocorticoid concentrations after single dose oral prednisolone or prednisone in 11 cats (5 normal-conditioned and 6-over-conditioned) was investigated using a two-drug crossover trial (3-week washout interval). Body condition was determined using criterion-referenced bioelectrical impedance together with plasma drug concentrations (prednisolone [active drug] and prednisone [pro-drug]) measured by HPLC. Although interconversion of each drug to the other was confirmed, a single 2mg/kg body weight oral dose of prednisolone produced significantly higher plasma prednisolone concentration (∼4-fold higher AUC) compared to prednisone. Significantly higher plasma drug concentrations in over-conditioned cats (∼2-fold) compared to normal-conditioned cats might explain their perceived increased risk for glucocorticoid associated side effects (hepatic lipidosis, diabetes mellitus). Findings suggest low comparative bioavailability of oral prednisone compared to prednisolone in cats and consideration of lean body mass or ideal body weight for dosing practices.

Plasma concentrations and therapeutic effects of budesonide in dogs with inflammatory bowel disease.

OBJECTIVE: To evaluate the pharmacokinetics and clinical efficacy of budesonide in dogs with inflammatory bowel disease (IBD). ANIMALS: 11 dogs (mean ± SD age, 5.7 ± 3.9 years; various breeds and body weights) with moderate or severe IBD. PROCEDURES: Each dog received a controlled-release formulation of budesonide (3 mg/m(2), PO, q 24 h) for 30 days (first day of administration was day 1). The concentration of budesonide and its metabolite (16-α-hydroxyprednisolone) was measured via liquid chromatography-tandem mass spectrometry in plasma and urine samples obtained on days 1 and 8 of treatment. On those days, plasma samples were obtained before the daily budesonide administration and 0.5, 1, 2, 4, and 7 hours after drug administration, whereas urine samples were obtained after collection of the last blood sample. A clinical evaluation was performed on the dogs before onset of drug administration and on days 20 and 30 after start of drug administration. RESULTS: The highest plasma concentration of budesonide and 16-α-hydroxyprednisolone on day 1 was detected at 1 hour and at 2 hours after drug administration, respectively. After standardization on the basis of specific gravity, the ratio between urinary concentrations of budesonide and 16-α-hydroxyprednisolone was 0.006 and 0.012 on days 1 and 8, respectively. The clinical response was adequate in 8 of 11 dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Budesonide was rapidly absorbed and metabolized in dogs with IBD. The drug gradually accumulated, and there was an adequate therapeutic response and no adverse effects.