Demonstrating Bioequivalence for Two Dose Strengths of Niraparib and Abiraterone Acetate Dual-Action Tablets Versus Single Agents: Utility of Clinical Study Data Supplemented with Modeling and Simulation

BACKGROUND AND OBJECTIVE

The combination of niraparib and abiraterone acetate (AA) plus prednisone is under investigation for the treatment of patients with metastatic castration-resistant prostate cancer (mCRPC) and metastatic castration-sensitive prostate cancer (mCSPC). Regular-strength (RS) and lower-strength (LS) dual-action tablets (DATs), comprising niraparib 100 mg/AA 500 mg and niraparib 50 mg/AA 500 mg, respectively, were developed to reduce pill burden and improve patient experience. A bioequivalence (BE)/bioavailability (BA) study was conducted under modified fasting conditions in patients with mCRPC to support approval of the DATs.

METHODS

This open-label randomized BA/BE study (NCT04577833) was conducted at 14 sites in the USA and Europe. The study had a sequential design, including a 21-day screening phase, a pharmacokinetic (PK) assessment phase comprising three periods [namely (1) single-dose with up to 1-week run-in, (2) daily dose on days 1-11, and (3) daily dose on days 12-22], an extension where both niraparib and AA as single-agent combination (SAC; reference) or AA alone was continued from day 23 until discontinuation, and a 30-day follow-up phase. Patients were randomly assigned in a parallel-group design (four-sequence randomization) to receive a single oral dose of niraparib 100 mg/AA 1000 mg as a LS-DAT or SAC in period 1, and patients continued as randomized into a two-way crossover design during periods 2 and 3 where they received niraparib 200 mg/AA 1000 mg once daily as a RS-DAT or SAC. The design was powered on the basis of crossover assessment of RS-DAT versus SAC. During repeated dosing (periods 2 and 3, and extension phase), all patients also received prednisone/prednisolone 5 mg twice daily. Plasma samples were collected for measurement of niraparib and abiraterone plasma concentrations. Statistical assessment of the RS-DAT and LS-DAT versus SAC was performed on log-transformed pharmacokinetic parameters data from periods 2 and 3 (crossover) and from period 1 (parallel), respectively. Additional paired analyses and model-based bioequivalence assessments were conducted to evaluate the similarity between the LS-DAT and SAC.

RESULTS

For the RS-DAT versus SAC, the 90% confidence intervals (CI) of geometric mean ratios (GMR) for maximum concentration at a steady state (Cmax,ss) and area under the plasma concentration-time curve from 0-24 h at a steady state (AUC 0-24h,ss) were respectively 99.18-106.12% and 97.91-104.31% for niraparib and 87.59-106.69 and 86.91-100.23% for abiraterone. For the LS-DAT vs SAC, the 90% CI of GMR for AUC0-72h of niraparib was 80.31-101.12% in primary analysis, the 90% CI of GMR for Cmax,ss and AUC 0-24h,ss of abiraterone was 85.41-118.34% and 86.51-121.64% respectively, and 96.4% of simulated LS-DAT versus SAC BE trials met the BE criteria for both niraparib and abiraterone.

CONCLUSIONS

The RS-DAT met BE criteria (range 80%-125%) versus SAC based on 90% CI of GMR for Cmax,ss and AUC 0-24h,ss. The LS-DAT was considered BE to SAC on the basis of the niraparib component meeting the BE criteria in the primary analysis for AUC 0-72h; abiraterone meeting the BE criteria in additional paired analyses based on Cmax,ss and AUC 0-24h,ss; and the percentage of simulated LS-DAT versus SAC BE trials meeting the BE criteria for both.

CLINICALTRIALS

GOV IDENTIFIER

NCT04577833.

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.

Pharmacokinetics, Safety, and Antitumor Effect of Apalutamide with Abiraterone Acetate plus Prednisone in Metastatic Castration-Resistant Prostate Cancer: Phase Ib Study

PURPOSE

Apalutamide is a next-generation androgen receptor (AR) inhibitor approved for patients with nonmetastatic castration-resistant prostate cancer (CRPC) and metastatic castration-sensitive prostate cancer. We evaluated the pharmacokinetics, safety, and antitumor activity of apalutamide combined with abiraterone acetate plus prednisone (AA-P) in patients with metastatic CRPC (mCRPC).

PATIENTS AND METHODS

Multicenter, open-label, phase Ib drug-drug interaction study conducted in 57 patients with mCRPC treated with 1,000 mg abiraterone acetate plus 10 mg prednisone daily beginning on cycle 1 day 1 (C1D1) and 240 mg apalutamide daily starting on C1D8 in 28-day cycles. Serial blood samples for pharmacokinetic analysis were collected on C1D7 and C2D8.

RESULTS

Systemic exposure to abiraterone, prednisone, and prednisolone decreased 14%, 61%, and 42%, respectively, when apalutamide was coadministered with AA-P. No increase in mineralocorticoid excess-related adverse events was observed. Patients without prior exposure to AR signaling inhibitors had longer median treatment duration and greater mean decrease in prostate-specific antigen (PSA) from baseline compared with those who had received prior therapy. Confirmed PSA reductions of ≥50% from baseline at any time were observed in 80% (12/15) of AR signaling inhibitor-naïve patients and 14% (6/42) of AR signaling inhibitor-treated patients.

CONCLUSIONS

Treatment with apalutamide plus AA-P was well tolerated and showed evidence of antitumor activity in patients with mCRPC, including those with disease progression on AR signaling inhibitors. No clinically significant pharmacokinetic interaction was observed between abiraterone and apalutamide; however, apalutamide decreased exposure to prednisone. These data support development of 1,000 mg abiraterone acetate plus 10 mg prednisone daily with 240 mg apalutamide daily in patients with mCRPC.

Pharmacokinetics of polatuzumab vedotin in combination with R/G-CHP in patients with B-cell non-Hodgkin lymphoma

Purpose

The phase Ib/II open-label study (NCT01992653) evaluated the antibody-drug conjugate polatuzumab vedotin (pola) plus rituximab/obinutuzumab, cyclophosphamide, doxorubicin, and prednisone (R/G-CHP) as first-line therapy for B-cell non-Hodgkin lymphoma (B-NHL). We report the pharmacokinetics (PK) and drug–drug interaction (DDI) for pola.

Methods

Six or eight cycles of pola 1.0–1.8 mg/kg were administered intravenously every 3 weeks (q3w) with R/G-CHP. Exposures of pola [including antibody-conjugated monomethyl auristatin E (acMMAE) and unconjugated MMAE] and R/G-CHP were assessed by non-compartmental analysis and/or descriptive statistics with cross-cycle comparisons to cycle 1 and/or after multiple cycles. Pola was evaluated as a potential victim and perpetrator of a PK drug–drug interaction with R/G-CHP. Population PK (popPK) analysis assessed the impact of prior treatment status (naïve vs. relapsed/refractory) on pola PK.

Results

Pola PK was similar between treatment arms and independent of line of therapy. Pola PK was dose proportional from 1.0 to 1.8 mg/kg with R/G-CHP. Geometric mean volume of distribution and clearance of acMMAE ranged from 57.3 to 95.6 mL/kg and 12.7 to 18.2 mL/kg/day, respectively. acMMAE exhibited multi-exponential decay (elimination half-life ~ 1 week). Unconjugated MMAE exhibited formation rate-limited kinetics. Exposures of pola with R/G-CHP were similar to those in the absence of CHP; exposures of R/G-CHP in the presence of pola were comparable to those in the absence of pola.

Conclusions

Pola PK was well characterized with no clinically meaningful DDIs with R/G-CHP. Findings are consistent with previous studies of pola + R/G, and support pola + R/G-CHP use in previously untreated diffuse large B-cell lymphoma.

Electronic supplementary material

The online version of this article (10.1007/s00280-020-04054-8) contains supplementary material, which is available to authorized users.

Old But Good: Modified-Release Prednisone in Rheumatoid Arthritis

BACKGROUND

Since more than 50 years glucocorticoids represent the milestone in the treatment of inflammatory diseases, including rheumatoid arthritis (RA). However, many patients with RA present a circadian rhythm in symptoms severity with a significant worsening in the morning, that correlates with cyclic changes in circulating hormones and cytokines. Classical steroid therapy given in the morning fails to intercept this pathophysiological phenomenon. In the last years, a novel formulation of prednisone has been developed in order to better fit these variations, improve efficacy and minimize adverse events (chronotherapy). This modified-release (MR) prednisone is administered in the evening at 10.00 p.m. and absorbed after about 4 hours.

METHODS

In this article, we reviewed the recent clinical trials evaluating the efficacy of MR prednisone in RA patients, including two randomized controlled double-blind clinical trials Circadian Administration of Prednisone in Rheumatoid Arthritis - 1 (CAPRA-1) and CAPRA-2 and other nonrandomized observational studies.

RESULTS

According to the available evidence, MR prednisone seems effective in ameliorating morning stiffness in RA patients.

CONCLUSION

In conclusion, the use of MR prednisone in the treatment regimen could be a costeffective choice in a significant proportion of RA patients, particularly in those with a clinical phenotype characterized by morning stiffness or morning recrudescence of pain. With regards to the safety, MR prednisone adverse events profile does not differ from that of IR glucocorticoids.

Intracellular IFN-γ and IL-2 expression monitoring as surrogate markers of the risk of acute rejection and personal drug response in de novo liver transplant recipients

Biomarker monitoring is needed in transplantation to reflect individual response to immunosuppressive drugs and graft outcome. We evaluated intracellular expression and soluble production of interferon-(IFN)-γ and interleukin-(IL)-2 as predictive biomarkers of acute rejection (AR) and personal drug response. Pharmacokinetic-pharmacodynamic profiles were determined in 47 de novo liver recipients treated with tacrolimus, mycophenolate mofetil and prednisone. Of the 47 patients, AR occurred in nine. There were no differences in drug concentrations between rejectors and non-rejectors. A pre-transplantation cut-off value of 55.80% for %CD8(+)-IFN-γ(+) identified patients at high risk of AR with a sensitivity of 75% and a specificity of 82%. In the first week post-transplantation, patients with a % inhibition for soluble IFN-γ, %CD8(+)-IFN-γ(+) and %CD8(+)-IL2(+) lower than 40% developed AR, showing low susceptibility to immunosuppressive drugs. Therefore, effector-T-cell response monitoring may help physicians to identify personal response to treatment and patients at high risk of AR.

Synthesis and properties of star oligo/poly(trimethylene carbonate)s with cholic acid moieties as cores

Star oligo/poly(trimethylene carbonate)s with cholic acid moieties as cores were synthesized by ring-opening polymerization of trimethylene carbonate (TMC) initiated by cholic acid with hydroxyl groups. The molecular weights of the star oligomers/polymers were controlled by adjusting the feed ratio of the initiator cholic acid to the monomer TMC. The star oligo/poly(trimethylene carbonate)s were characterized by Fourier transform infrared spectroscopy (FT-IR), (1)H nuclear magnetic resonance spectroscopy ((1)H-NMR) and combined size-exclusion chromatography and multiangle laser light scattering (SEC-MALLS) analysis. The water contact angles of the star oligo/poly(trimethylene carbonate)s were measured. Using 3-(4,5 dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, the star oligo/poly(trimethylene carbonate) was proved to have a low cytotoxicity. A microsphere drug-delivery system based on a star polymer was fabricated and its in vitro drug release property was studied.

Iontophoresis-facilitated delivery of prednisolone through throat skin to the trachea after topical application of its succinate salt

PURPOSE

The possibility of direct delivery of steroids through the skin to the trachea and the effect of iontophoresis on delivery efficacy were evaluated after the application of an ionic steroidal prodrug, prednisolone sodium succinate (PS-Na), to the throat skin.

METHODS

Fluorescein sodium salt (FL-Na) and PS-Na were applied as model compounds at a concentration of 1% in pH 7.4 phosphate-buffered saline to the throat skin of hairless rats, and constant current-cathodal iontophoresis (0.4 mA/cm(2)) was performed for 8 or 10 h.

RESULTS

In vitro permeation experiment involving cathodal iontophoresis through excised hairless rat abdominal skin revealed 30- and 10-times higher levels of skin permeation of PS and its active drug, prednisolone (P), than those induced without iontophoresis. In vivo iontophoresis treatment of the rat's throat skin produced 2.6-, 1.6- and 12-times higher FL, PS and P concentrations, respectively, in the trachea than those observed without iontophoresis.

CONCLUSION

The present results suggest the usefulness of topical application of the ionic steroidal prodrugs onto throat skin followed by iontophoresis treatment for directly delivering the steroid to the trachea.

Oral anticoagulation with warfarin is significantly influenced by steroids and CYP2C9 polymorphisms in children with cancer

Clinical management of warfarin therapy is complex, and dosing algorithms do not include genetic factors or interactions with other drugs for warfarin dose determinations. We evaluated the interaction of warfarin and CYP2C9 polymorphisms and concomitant corticosteroids in 29 children with cancer. Children with heterozygous polymorphisms of CYP2C9 achieved target INR sooner and more frequently had INR above the target level, compared to children without mutations. Children on concomitant steroids had significantly lower warfarin requirements. Thus, awareness of CYP2C9 genotype and steroid-induced responsiveness to warfarin may be important when administrating oral anticoagulation in children.

Biowaiver monographs for immediate release solid oral dosage forms: prednisone

Literature data relevant to the decision to allow a waiver of in vivo bioequivalence (BE) testing for the approval of immediate release (IR) solid oral dosage forms containing prednisone are reviewed. Due to insufficient data prednisone cannot be definitively classified according to the current Biopharmaceutics Classification System (BCS) criteria as both the solubility and the permeability of prednisone are on the borderline of the present criteria of BCS Class I. Prednisone's therapeutic indications and therapeutic index, pharmacokinetics and the possibility of excipient interactions were also taken into consideration. Available evidence indicates that a biowaiver for IR solid oral dosage forms formulated with the excipients tabulated in this article would be unlikely to expose patients to undue risks.

A Pharmacokinetic/Pharmacodynamic Approach to Predict Total Prednisolone Concentrations in Human Plasma

Prednisolone and prednisone are two widely used corticosteroids for various inflammatory and immune diseases. Prednisolone is the active form of prednisone in vivo. Total prednisolone in plasma exhibits nonlinear pharmacokinetics mainly due to its nonlinear protein binding. Other factors such as reversible metabolism (or interconversion between prednisolone and prednisone), competitive protein binding from endogenous cortisol, cortisol circadian rhythm, and prednisolone mediated cortisol suppression complicate prednisolone pharmacokinetics. This study was aimed to develop a new approach to describe the nonlinear pharmacokinetics of total prednisolone and predict total prednisolone concentrations in plasma. Based on literature datasets, a linear two-compartment pharmacokinetic model was developed to adequately describe the reversible metabolism between free prednisone and prednisolone. Cortisol and prednisolone protein binding were described via the sum of a Langmuir and linear type binding. The endogenous cortisol circadian rhythm and cortisol suppression during prednisone or prednisolone exposure were described with a previously reported linear release rate pharmacokinetic/pharmacodynamic (PK/PD) model. By combining the pharmacokinetic models for free prednisone and prednisolone, the linear release rate model for cortisol suppression, and competitive protein binding between cortisol and prednisolone, we were able to predict total prednisolone concentrations in plasma. The predicted total prednisolone concentrations in plasma were in good agreement with the literature reported data. Thus, this PK/PD approach shows that the combination of nonlinear protein binding, cortisol circadian rhythm, and cortisol suppression could account for the nonlinearity of total prednisolone. In addition, it also allows a valid prediction of total prednisolone in plasma after either prednisone or prednisolone administration.

Concentrations of Mycophenolic Acid and Glucuronide Metabolites Under Concomitant Therapy With Cyclosporine or Tacrolimus

Mycophenolate mofetil [MMF, the prodrug of mycophenolic acid (MPA)] is usually administered at double doses with cyclosporine than with tacrolimus because it is believed that MPA exposure is lower during cyclosporine therapy. This study aimed to compare 12 hour, steady-state concentration-time profiles of MPA and its phenol- and acyl-glucuronide metabolites (MPAG and AcMPAG, respectively) in stable kidney transplant recipients maintained either on cyclosporine (n = 12) or tacrolimus (n = 12). During the absorption phase in the cyclosporine group, dose-normalized concentrations of total and free MPA were significantly higher but the overall area under the concentration-time curve (AUC0-12) was not significantly different. Additionally, exposure to AcMPAG was higher in the cyclosporine group (P < 0.05). Ten of 12 patients in the cyclosporine group were on ketoconazole therapy; however, the exposure to MPA or MPAG was not different when MMF was given orally to Sprague-Dawley rats with or without ketoconazole. In conclusion, cyclosporine modulates the disposition of MPA and metabolites differently from tacrolimus; however, patients on cyclosporine may not require double doses of MMF to achieve the same exposure.

Pharmacokinetic profiling of cyclosporine microemulsion during the first 3 weeks after simultaneous pancreas-kidney transplantation

The optimal effect of therapy with cyclosporine (CsA) seeks to minimize undesirable side effects while maximizing immunosuppression. This balance, depends on CsA exposure, which may be characterized by the area under the concentration-time-curve (AUC). Therefore, we tested the pharmacokinetic profile of microemulsion CsA as a superior approach to guide clinical immunosuppression after de novo simultaneous pancreas-kidney transplantations. We examined 10 consecutive pancreas-kidney recipients with type 1 diabetes and end-stage renal disease. All patients were treated with a regimen consisting of CsA, mycophenolate mofetil (MMF), and prednisone. Full (9-point) pharmacokinetic studies (C0, C1, C2, C3, C4, C6, C8, C10, C12) were performed on week 1 and during week 3 to examine CsA pharmacokinetic profiles. Mean AUC0-12 of 4431 +/- 2400 microg x h/L at week 1 remained stable at week 3 (5119 +/- 1190 microg x h/L). The C6 sampling time displayed the best correlation with AUC0-12 (r2 = 0.881), followed by C3 (r2 = 0.758). Our preliminary data after simultaneous pancreas-kidney transplantation support the hypothesis that C3 or C6 sampling is a more accurate predictor of the AUC0-12 than C0. The combination of two samplings, namely C3 + C6 (r2 = 0.938) or C2 + C6 (r2 = 0.955) proved excellent prediction of exposure after simultaneous pancreas-kidney transplantation.

Pharmacokinetics of prednisone and prednisolone in a case of hypothyroidism: effect of replacement therapy

We found this particular case during the course of a clinical trial designed to assess the pharmacokinetics of oral prednisone in normal and diseased children. The plasma concentrations of prednisone, its main metabolite prednisolone, and endogenous cortisol were measured by HPLC at selected times during 8-h periods starting at 7:30 a.m. One 9.9-year-old administered prednisone 0.5mg/kg p.o. was found to be hypothyroid (TSH: 351microIU/mL; fT4: <2pg/mL; fT3: <1pg/mL); four age-matched normal boys (aged 6.6+/-4.9 years) served as a control group. In comparison with the controls, the hypothyroid boy showed a marked increase in the total AUC of prednisone (3360microg h/L versus 215+/-83microg h/L) and prednisolone (4040microg h/L versus 724+/-77microg h/L), and an altered pattern of endogenous cortisol, which is known to be impaired in hypothyroid subjects. After 6 months of thyroxine replacement therapy (75microg/day), the AUCs of prednisone and prednisolone returned to normal values (prednisone: 248microg h/L; prednisolone: 528microg h/L), as did the pattern of circadian cortisol secretion. In conclusion, our data indicate that the pharmacokinetics of prednisone and prednisolone can be profoundly altered by hypothyroidism, and subsequently restored by thyroxine replacement therapy.

Concentration-controlled use of sirolimus associated with reduced exposure of cyclosporine in black recipients of primarily living renal allograft donors: 12-month results

AIM

This study was designed to identify optimal therapeutic sirolimus (SRL) concentrations in black kidney transplant recipients on reduced cyclosporine (CsA) exposure and prednisone.

METHODS

Seventy patients (64 living/six deceased) received CsA (8-10 mg/kg/d), prednisone, and 15 mg loading dose followed by 5-mg fixed doses of SRL till day 7 when they were randomized to maintain SRL trough concentrations (high-performance liquid chromatography) of 8-12 (GI = 34) or 15-20 (GII = 36) ng/mL.

RESULTS

Mean CsA concentrations were 109 +/- 53 vs. 89 +/- 41 ng/mL and 75 +/- 54 vs. 60 +/- 35 ng/mL (ns) at 2 and 6 months. Accordingly, mean SRL trough concentrations were 12.4 +/- 6.1 vs. 20.0 +/- 9.5 ng/mL (p < 0.001) and 10.8 +/- 5.8 vs. 18.0 +/- 6.1 ng/mL (p < 0.001). The incidence of biopsy-proven acute rejection [13% (GI: 18% vs. GII: 8%, ns)], graft loss or death was 16% (GI: 21% vs. GII: 11%, ns]. There were no deaths and three graft losses (GI = 1; GII = 2). Creatinine clearance was higher in GI (64.5 +/- 17 vs. 54.4 +/- 14.7 mL/min, p = 0.011). The incidence of post-transplant diabetes mellitus was 13% and no CMV disease was observed.

CONCLUSION

In black recipients of primarily living renal allograft donors reduced CsA exposure and SRL concentration-controlled regimens produced low incidences of acute rejection, post-transplant diabetes mellitus and CMV disease, with no significant impairment in graft function.

Cyclosporine Monitoring With 2-Hour Postdose Levels in Heart Transplant Recipients

Cyclosporine therapeutic drug monitoring based on 2-hour postdose concentration (C2) compared with conventional trough concentration (C0) can improve clinical outcomes for de novo renal and liver transplant patients. However, in heart transplant patients, published studies are limited. To determine the clinical significance of C2 compared with C0 following orthotopic heart transplantation, the authors measured CsA at C0 and C2 and estimated CsA area under the curve (AUC) using Bayesian estimation and 4 sparse sample algorithms in a cross section of 31 adult patients receiving triple-drug immunosuppression with CsA, mycophenolate mofetil (MMF), and prednisone. CsA was measured using a validated HPLC method. Endomyocardial biopsies were graded based on the ISHLT system. Mean +/- SD values for CsA dose, C0, and C2 were 4.8 +/- 1.4 mg/kg/d, 240 +/- 62 microg/L, and 1319 +/- 469 microg/L, respectively. Correlation with AUC, using different estimation algorithms, was better for C2 (r(2) = 0.79-0.99) than for C0 (r(2)= 0.11-0.52). The mean +/- SD values for C0 (microg/L) and C2 (microg/L) for rejectors (n = 3) were 215 +/- 68 and 949 +/- 204 versus 242 +/- 62 and 1359 +/- 474 for the nonrejectors (P = 0.66 and 0.12, respectively). Fisher exact test P values using the median as threshold value for C0 and C2 (234 microg/L and 1251 microg/L, respectively) were 0.6 and 0.1. Analysis of the data revealed that C0 values in rejectors have wider variability than C2. There were no rejectors among the 16 patients exceeding the C2 median value; for C0, however, there was not an easily identifiable threshold value. There is a trend for a significant relationship between C2 and the incidence of rejection, but the number of rejectors was too small to reach statistical significance. A prospective concentration-control de novo study design is recommended as the most appropriate way to fully evaluate the potential utility of C2 monitoring in heart transplant patients.

The bioavailability of IV methylprednisolone and oral prednisone in multiple sclerosis

Oral prednisone (1)might be a convenient, inexpensive alternative to IV methylprednisolone (IVMP) if the bioequivalent dose was known. We compared the total amount of steroid absorbed after 1250 mg oral prednisone vs 1 gram IVMP in 16 patients with multiple sclerosis (MS). At 24 hours, the mean area under the concentration-time curve (AUC), the main component of bioavailability, did not differ between groups (p = 0.122). This suggests that the amount of absorbed corticosteroid is similar after either steroid at these doses.

Identification of budesonide and prednisone as substrates of the intestinal drug efflux pump P-glycoprotein

Steroid resistance is a major problem in the management of patients with inflammatory bowel disease. In Crohn disease, poor response to corticosteroids has been related to increased expression of the drug efflux pump, P-glycoprotein. However, it has not been investigated thoroughly whether corticosteroids commonly used for drug therapy in inflammatory bowel disease are substrates of P-glycoprotein. We tested the hypothesis that budesonide and prednisone are substrates of P-glycoprotein thereby possibly contributing to variable therapeutic effects. Polarized, basal to apical transport of [3H]budesonide and [3H]prednisone was studied in monolayers of L-MDR1 cells (LLC-PK1 cells stably transfected with human MDR1 cDNA) and Caco-2 cells, both of which express P-glycoprotein in their apical membrane. Drug transport was measured during 4 hours at substrate concentrations of 5 microM. Net transport rates and permeability coefficients were calculated. Inhibition of P-glycoprotein-mediated transport across Caco-2 monolayers was determined after addition of the P-glycoprotein inhibitor PSC-833. The net transport rate from the basolateral to the apical side was significantly higher in L-MDR1 than in LLC-PK1 cells for both budesonide and prednisone. Apparent permeability coefficients of budesonide and prednisone reflected polarized transport from basal to apical. PSC-833 inhibited the polarized transport of both corticosteroids. In conclusion, budesonide and prednisone were identified as substrates of the intestinal drug efflux pump, P-glycoprotein. Therefore, drug secretion via P-glyco-protein into gut lumen might play a more important role in pharmacokinetics and pharmacodynamics of these corticosteroids than currently appreciated in gastroenterological practice.

Glucocorticoid pharmacokinetics and growth retardation in children with renal transplants

Long-term glucocorticoid treatment contributes to the growth retardation in children after renal transplantation. We investigated whether determination of prednisone (PN) and prednisolone (PL) in plasma and PN, PL, and 6-beta-hydroxyprednisolone (betaOH-PL) in urine could help to predict growth. PN and PL pharmacokinetics were studied in 36 children, from 5 to 15 years of age, receiving daily (D) or alternate-day (AD) oral PN treatment. Statural growth velocity was evaluated over a 1-year period. We compared three groups of children according to the growth kinetics during the study year (catch-up, stable, or decline) for clinical and pharmacokinetic parameters. A multiple linear regression analysis was performed in order to determine pharmacokinetic parameters able to explain height 1 year after inclusion. Height at the beginning of the study, creatinine clearance, and type of D or AD treatment explained 94.2% of height variance 1 year after inclusion. Only PL clearance was associated with growth evolution, but introduction of PL clearance in the multivariate model did not improve the variance of height accounted for by the previous model. We, therefore, do not recommend using glucocorticoid pharmacokinetics to predict growth retardation in children with renal transplantation.

Effects of different glucocorticoid treatments on serum acute phase proteins in dogs

The serum concentrations of haptoglobin, caeruloplasmin, C-reactive protein and serum amyloid A were measured in three groups of seven healthy dogs. Group 1 received a single dose of 1.1 mg/kg methylprednisolone acetate, administered subcutaneously; group 2 received 1 mg/kg per day of prednisone administered orally for three weeks; and group 3 received 2.2 mg/kg per day of prednisone administered orally for seven days. Before the administration of the glucocorticoids the serum concentrations of all the acute phase proteins were within the authors' laboratory reference ranges. After the administration of the drugs there were significant increases in the concentration of haptoglobin in all three groups, the increases being larger in groups 2 and 3. In contrast, the concentrations of C-reactive protein, caeruloplasmin and serum amyloid A were not affected.

Acute Interstitial Nephritis Due to Pantoprazole

OBJECTIVE:

To describe what is believed, as of November 4, 2003, to be the first case published in the literature of acute interstitial nephritis (AIN) due to pantoprazole.

CASE SUMMARY:

A 77-year-old white woman presented to the hospital with elevated serum creatinine, oliguria for the past 24 hours, arthralgia, fatigue, fever, and bilateral flank pain. The patient had initiated treatment with oral pantoprazole 40 mg/d for gastroesophageal reflux 2 months prior to admission. After 5 weeks of therapy, she stopped taking pantoprazole due to general malaise. Upon admission, all home medications, including pantoprazole, were reinitiated based on the patient's medication list. Serum creatinine increased to 6.1 mg/dL on day 4 of admission from a baseline of 1.0 mg/dL. Pantoprazole therapy was promptly discontinued, and prednisone 40 mg/d was initiated. Urinalysis revealed eosinophils, and a subsequent renal biopsy confirmed a diagnosis of AIN. The serum creatinine level gradually declined over 2 weeks, and the patient was discharged home with a serum creatinine level of 1.6 mg/dL. The Naranjo probability scale suggests a highly probable relationship between AIN and pantoprazole therapy in this patient.

DISCUSSION:

Drug hypersensitivity reactions are the most common cause of AIN. There have been several reported cases of omeprazole-induced AIN. Although there are very few prospective data on the efficacy of treatment of drug-induced AIN, corticosteroids may have a role in recovery of renal function. Prednisone doses of 1 mg/kg/d have been suggested.

CONCLUSIONS:

Physicians should be aware that drug-induced AIN can be associated with proton-pump inhibitors. Early detection of this rare adverse reaction may prevent acute renal insufficiency.

Prednisone metabolism in recipients of kidney or liver transplants and in lung recipients receiving ketoconazole

BACKGROUND

Actual prednisone exposure in low-dose prednisone regimens, in part determined by cytochrome P450 metabolism, has been shown to be important for allograft survival.

METHODS

Prednisolone (the principal active metabolite of prednisone) metabolism was determined in eight nontransplant patients and in transplant recipients receiving oral prednisone maintenance therapy (20 kidney and 6 liver recipients receiving cyclosporine [CsA] and eight lung recipients receiving ketoconazole and CsA or tacrolimus [FK506]).

RESULTS

Prednisolone area under the curve (AUC)-dose-normalized (PNAUCn) to 1 mg/kg was 8,288+/-1,513 ng.hr/mL in kidney recipients, versus 4,826+/-999 ng/mL per hr in healthy subjects (P<0.001); it was also increased in liver recipients versus healthy subjects (11,456+/-1,214 ng.hr/mL, P<0.001). Liver recipients also metabolized prednisolone more slowly than kidney recipients (P<0.001). PNAUCn in lung recipients was similar in kidney recipients despite the effect of ketoconazole to slow CsA metabolism. In kidney transplant recipients, the rate of CsA metabolism was correlated with the rate of prednisolone metabolism (r=0.54, P=.026). Basal cortisol levels in all transplant recipients were lower than in healthy subjects, suggesting more prednisolone exposure in transplant patients.

CONCLUSIONS

Prednisolone metabolism is slower in solid-organ transplant recipients than in healthy subjects. The slower metabolism of prednisolone, particularly in liver recipients, may help explain the immunologic effectiveness of low-dose prednisone regimens in these patients.

Selecting a systemic corticosteroid for acute asthma in young children

Oral corticosteroids are as effective as intravenous therapy for treating acute exacerbations of asthma. They are available in tablets that can be crushed and mixed with soft food or syrup, and in a variety of liquid formulations that differ in volume required, palatability, patient acceptance, and cost. The most important consideration in product selection for a young child is that the doses can be easily swallowed and retained.

Effect of rofecoxib on prednisolone and prednisone pharmacokinetics in healthy subjects

Patients receiving nonsteroidal anti-inflammatory drug therapy may also require administration of corticosteroids, particularly patients with rheumatoid arthritis. To investigate the effect of rofecoxib on the single-dose pharmacokinetics of oral prednisone and intravenous prednisolone, the authors conducted a randomized, double-blind, placebo-controlled crossover study in 12 healthy subjects. Oral rofecoxib (250.0 mg/day for 14 days) failed to influence prednisone or prednisolone pharmacokinetics after intravenous prednisolone or oral prednisone administration. The geometric mean ratio (GMR) (90% confidence interval) of prednisolone AUC infinity (rofecoxib/placebo) following intravenous and oral corticosteroid was 0.97 (0.94, 1.01) and 0.99 (0.91, 1.08), respectively. Similarly, the prednisone AUC infinity GMRs (rofecoxib/placebo) after intravenous and oral corticosteroid were 1.03 (0.95, 1.11) and 1.08 (0.92, 1.28), respectively. The absence of an effect of rofecoxib on the pharmacokinetics of oral prednisone or intravenous prednisolone indicates that no adjustment in dose of this corticosteroid is necessary when administered concurrently with rofecoxib.

Osteoblastic 11beta-hydroxysteroid dehydrogenase type 1 activity increases with age and glucocorticoid exposure

The risk of glucocorticoid-induced osteoporosis increases substantially with age but there is considerable individual variation. In recent studies we have shown that the effects of glucocorticoids on bone are dependent on autocrine actions of the enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1); expression of 11beta-HSD1 in osteoblasts (OBs) facilitates local synthesis of active glucocorticoids with consequent effects on osteoblastic proliferation and differentiation. Using primary cultures of human OBs, we have now characterized the age-specific variation in osteoblastic 11beta-HSD1 and defined enzyme kinetics and regulation using natural and therapeutic glucocorticoids. 11beta-HSD1 reductase activity (cortisone to cortisol conversion) was recognized in all OB cultures and correlated positively with age (r = 0.58 with all cultures, p < 0.01, and n = 18; r = 0.87 with calcaneal-derived cultures, p < 0.001, and n = 14). Glucocorticoid treatment caused a time- and dose-dependent increase in 11beta-HSD1 activity over control (e.g., dexamethasone [DEX; 1 microM], 2.6-fold +/- 0.5 (mean +/- SE), p < 0.001, and n = 16; cortisol (100 nM), 1.7-fold +/- 0.1, p < 0.05, and n = 14). Similar increases in 11beta-HSD1 mRNA expression were indicated using real-time quantitative reverse-transcription polymerase chain reaction (RT-PCR) analyses (3.5-fold with DEX, p < 0.01; 2.5-fold with cortisol, p < 0.05). The capacity of 11beta-HSD1 to metabolize the synthetic glucocorticoids prednisone and prednisolone was investigated in human OBs (hOBs) and fetal kidney-293 cells stably transfected with human 11beta-HSD1 cDNA. Transfected cells and hOBs were able to interconvert prednisone and prednisolone with reaction kinetics indistinguishable from those for cortisone and cortisol. To assess the in vivo availability of substrates for osteoblastic 11beta-HSD1, plasma cortisone and prednisone levels were measured in normal males before and after oral prednisolone (5 mg). The 9:00 a.m. serum cortisone levels were 110 +/- 5 nmol/liter and prednisone levels peaked at 78 +/- 23 nmol/liter 120 minutes after administration of prednisolone. Thus, therapeutic use of steroids increases substrate availability for 11beta-HSD1 in bone. These studies indicate that activation of glucocorticoids at an autocrine level within bone is likely to play an important role in the age-related decrease in bone formation and increased risk of glucocorticoid-induced osteoporosis.

Prednisone per os is likely to have limited efficacy in horses

Based on its efficacy for the treatment of human asthma, the corticosteroid prednisone is commonly used in horses for treatment of recurrent airway obstruction. However, recent studies have failed to show any benefit of prednisone tablets for the treatment of this condition. The purpose of this study was to determine why oral prednisone has poor efficacy for the treatment of heaves in horses. In a crossover study, 5 horses were given the following treatments: prednisone tablets, prednisone liquid, prednisolone tablets, prednisolone liquid and i.v. prednisolone sodium succinate (positive control). Blood samples were taken before drug administration and at selected time points during a 24 h period. Serum concentrations of prednisone and prednisolone were determined in order to evaluate gastrointestinal absorption and hepatic metabolism. Serum concentrations of the endogenous glucocorticoid hydrocortisone were also determined as an indicator of the biological activity of the drugs. Both prednisolone tablets and liquid were absorbed rapidly, with prednisolone detectable in serum within 15 min of administration and with peak concentrations occurring within 45 min. Small amounts of prednisone were detected in the serum samples after administration of both prednisone tablets and liquid. Prednisolone was not detected in serum samples after administration of prednisone liquid and was detected in serum samples from only one horse after administration of prednisone tablets. Endogenous hydrocortisone production was suppressed when horses received prednisolone. The results of these studies indicate that prednisone has poor efficacy for the treatment of heaves because it is poorly absorbed and the active metabolite prednisolone is rarely produced. In contrast, prednisolone tablets have excellent bioavailability and should be useful as a therapeutic agent in horses.

Dose-adjusted EPOCH chemotherapy for untreated large B-cell lymphomas: a pharmacodynamic approach with high efficacy

We hypothesized that incremental improvements in the cyclophosphamide-doxorubicin-vincristine-prednisone (CHOP) chemotherapy regimen through optimization of drug selection, schedule, and pharmacokinetics would improve outcome in patients with large B-cell lymphomas. A prospective multi-institutional study of administration of etoposide, vincristine, and doxorubicin for 96 hours with bolus doses of cyclophosphamide and oral prednisone (EPOCH therapy) was done in 50 patients with previously untreated large B-cell lymphomas. The doses of etoposide, doxorubicin, and cyclophosphamide were adjusted 20% each cycle to achieve a nadir absolute neutrophil count below 0.5 x 10(9)/L. The median age of the patients was 46 years (range, 20-88 years); 24% were older than 60 years; and 44% were at high-intermediate or high risk according to International Prognostic Index (IPI) criteria. There was a complete response in 92% of patients, and at the median follow-up time of 62 months, the progression-free survival (PFS) and overall survival (OS) rates were 70% and 73%, respectively. Neither IPI risk factors nor the index itself was associated with response, PFS, or OS. Doses were escalated in 58% of cycles, and toxicity levels were tolerable. Significant inverse correlations were observed between dose intensity and age for all adjusted agents, and drug clearance of doxorubicin and free etoposide was also inversely correlated with age (r = -0.54 and P(2) =.08 and r = -0.45 and P(2) =.034, respectively). Free-etoposide clearance increased significantly during successive cycles (P(2) =.015). Lymphomas with proliferation of at least 80% had somewhat lower progression and those expressing bcl-2 had significantly higher progression (P(2) =.04). Expression of bcl-2 may discriminate the recently described activated B-like from germinal-center B-like large-cell lymphomas and provide important pathobiologic and prognostic information. Dose-adjusted EPOCH may produce more cell kill than CHOP-based regimens. Dynamic dose adjustment may overcome inadequate drug concentrations, particularly in younger patients, and compensate for increased drug clearance over time.

Effect of food on everolimus absorption: quantification in healthy subjects and a confirmatory screening in patients with renal transplants

STUDY OBJECTIVE

To quantify the influence of a high-fat meal on the oral bioavailability of the immunosuppressant everolimus in a single-dose study in healthy subjects and to confirm the results in a small food-effect screening assessment in patients with renal transplants who were receiving multiple-dose everolimus.

DESIGN

Randomized, open-label, crossover, single-dose study and confirmatory screening.

SETTING

Phase 1 unit for the single-dose study and two German hospitals for the patient screening.

SUBJECTS

Twenty-four healthy male volunteers; six clinically stable patients with renal transplants who were originally part of a phase I dose-escalation study.

INTERVENTION

The 24 healthy men received everolimus 2 mg orally under fasting conditions and after a high-fat meal. The six patients received everolimus 2.5 mg/day orally, in addition to cyclosporine and prednisone. On two occasions, a pharmacokinetic profile was obtained over the dosing interval after drug administration under fasting conditions and after a high-fat meal in a randomized sequence.

MEASUREMENTS AND MAIN RESULTS

In the single-dose study in healthy subjects, a high-fat meal delayed everolimus time to maximum concentration (Tmax) by a median 1.25 hours, reduced peak blood concentration (Cmax) by 60%, and reduced area under the concentration-time curve (AUC) by 16%. In the multiple-dose screening in patients with renal transplants, a high-fat meal delayed Tmax by a median 1.75 hours and reduced Cmax by 53% and AUC by 21%. Everolimus trough levels showed no food effect, whereas the peak-trough fluctuation was dampened by 52%.

CONCLUSIONS

A high-fat meal modestly reduced everolimus AUC. To minimize longitudinal variability in exposure, everolimus should be administered consistently either with food or without food.

Effects of oral prasterone (dehydroepiandrosterone) on single-dose pharmacokinetics of oral prednisone and cortisol suppression in normal women

This study sought to determine effects of multiple dosing of prasterone (DHEA, dehydroepiandrosterone) on the pharmacokinetics of prednisolone and endogenous cortisol secretion. These drugs are likely to be coadministered to patients with systemic lupus erythematosus. Fourteen normal women (ages 30.1 +/- 5.4 years) received single-dose oral prednisone (20 mg) before and after 200 mg/day of oral prasterone for one menstrual cycle (approximately 28 days). Identical assessments, timed to onset of menses, were conducted pretreatment (baseline) and at days 28 and 29 of prasterone treatment and included serum total and free prednisolone, prednisone, DHEA, DHEA-S (dehydroepiandrosterone sulfate), ACTH-stimulated cortisol, and sex hormones and 24-hour urine free cortisol. Pharmacokinetic parameters of prednisolone as assessed by Cmax, t 1/2, AUC, or serum protein binding were not affected by prasterone. The ACTH-stimulated plasma cortisol concentrations were mildly reduced, but 24-hour urinefree cortisol excretion was unchanged during prasterone administration. Serum androstenedione and testosterone increased, while no changes in serum estradiol or estrone occurred. The administration of 200 mg oral prasterone produced serum concentrations of DHEA and DHEA-S significantly greater than endogenous levels. Chronic dosing with 200 mg/day of prasterone did not alter either prednisolone pharmacokinetics or inhibition of cortisol secretion by prednisolone.

Safety and efficacy of TOR inhibitors in pediatric renal transplant recipients

Information about the pharmacokinetics, safety, and efficacy of target of rapamycin (TOR) inhibitors, such as sirolimus and everolimus, in pediatric renal transplant recipients is limited. In an ascending single-dose pharmacokinetic study of sirolimus in pediatric dialysis patients, no clinically significant association was observed between patient age and absorption of sirolimus from the gastrointestinal tract. However, young pediatric patients (5 to 11 years of age) exhibited significantly greater apparent oral clearances, suggesting that pediatric patients require slightly higher doses than do adults when adjusted for body weight or surface area. Similarly, in studies performed in pediatric renal transplant recipients, the half-life of sirolimus was shorter and the clearance was greater in younger patients. On the other hand, in single-dose pharmacokinetic studies of everolimus, the apparent clearance was reduced in pediatric renal transplant recipients compared with clearance in adults. This reduced clearance was attributed to a smaller apparent volume of distribution in pediatric patients, rather than to a difference in terminal half-life. This suggested that, although the adult 12-hour dosing interval was appropriate for pediatric patients, they would require reduced dosing based on body size compared with adults. In a large trial (N = 719) of sirolimus versus azathioprine in combination with cyclosporine microemulsion and prednisone, 6 pediatric patients (13 to 18 years of age) received sirolimus at 2 mg/d, 3 received sirolimus at 5 mg/d, and 3 received azathioprine. Seven of the nine patients who received sirolimus experienced no rejection episodes. Six infectious episodes occurred in the 6 patients receiving sirolimus at 2 mg/d, 10 episodes occurred in the 3 patients receiving sirolimus at 5 mg/d, and 8 episodes occurred in the 3 patients receiving azathioprine. At 6 months after transplantation, renal function was similar in all 3 groups, although there was a statistically nonsignificant increase in the group receiving sirolimus at 5 mg/d. The mean cholesterol and triglyceride levels were generally comparable in all 3 groups. TOR inhibitors are promising agents for the prevention of graft rejection in pediatric renal transplant recipients, but more pharmacokinetic data are required to assess the optimal dosing regimens in this population. In addition, further data are needed on the efficacy and safety of TOR inhibitors in combination with other agents in pediatric transplantation recipients to best assess the role of TOR inhibition in corticosteroid and/or calcineurin inhibitor-sparing regimens.

Pharmacokinetic and adrenal interactions of IL-10 and prednisone in healthy volunteers

The pharmacokinetic and adrenal interactions of recombinant human interleukin-10 and prednisolone were examined in this open-label, randomized, four-way crossover study in 12 healthy adult male volunteers. Single doses of IL-10 (8 micrograms/kg s.c.), IL-10 with prednisone (15 mg p.o.), placebo with prednisone, or placebo were administered on four separate occasions with at least 3-week interceding washout periods. Measurements included plasma prednisone, prednisolone and cortisol, unbound prednisolone, and serum IL-10 concentrations. Pharmacokinetic parameters were determined using noncompartmental and model-fitting analysis, while area analysis and an indirect response model were used to assess cortisol dynamics. IL-10 exhibited prolonged serum concentrations owing to dual-absorption processes that were largely unaffected by prednisone. The Cmax values were about 3 ng/mL, while the tmax occurred at 7 to 9 hours. Prednisolone exhibited rapid systemic kinetics with a Cmax of 235 ng/mL, tmax at 1.11 hours, and t1/2 of 2.54 hours with no significant alterations owing to IL-10. Both prednisolone and prednisolone/IL-10 caused marked suppression of cortisol concentrations with similar magnitude and IC50 values; however, IL-10 alone significantly increased the 24-hour AUC of cortisol by 20%. Thus, IL-10 and prednisolone do not interact in disposition or adrenal suppression to a clinically significant degree.

Generic immunosuppressant use in solid organ transplantation

Although economics may be the driving force for generic development, these forces must be tempered by consumer safety and efficacy. Studies to date imply that we are gaining balance in attempts to reconcile these issues. With the development of more generic immunosuppressants imminent, the transplant community must continue to enforce their high standards of a research driven discipline where the transition from research to clinical practice is often seamless. Higher academic demands will continue to be expected for any generic developed for use in transplantation. Whether or not generic availability will subsequently impact other areas of transplantation such as legislative policies for reimbursement, compliance, and long-term graft survival has not been quantified and requires further study.

Diltiazem retards the metabolism of oral prednisone with effects on T-cell markers

The area under the time-plasma concentration curve (AUC) was measured for prednisolone (the major active metabolite of prednisone) after ingestion of 15 mg of prednisone (phase 1) and again after 3 d of oral diltiazem (180 mg/d) followed by the same dose of oral prednisone (phase 2) in eight normal adult patients. Diltiazem increased the prednisolone AUC by 21% (range 3-38%), from 1297 +/- 157 ng/h/mL to 1560 +/- 169 ng/h/mL (p = 0.001). This effect was associated with a greater decrease from baseline in CD3+ lymphocyte number at 4 h after prednisone ingestion (596 +/- 175 vs. 516 +/- 140, p = 0.05), a larger percentage decrease of circulating CD3+ lymphocytes at 8 h (43 +/- 19% vs. 53 +/- 19%, p = 0.04), and a decrease in the number of CD3+ CD8+ T cells at 4 h post-prednisone ingestion (279 +/- 81 vs. 236 +/- 51, p = 0.04). Diltiazem retards prednisolone metabolism and when used chronically with prednisone could conceivably, in some patients, enhance its immunologic and other clinical effects. Potentiation of prednisone side-effects by diltiazem may be of special interest in pediatric patients, and possible diltiazem-prednisone interactions merit study in this population.

Validity of area-under-the-curve analysis to summarize effect in rheumatoid arthritis clinical trials

There is a continuing interest in increasing the statistical efficiency of the analysis of clinically meaningful endpoints in rheumatology. One issue that is attracting increasing attention is whether the conventional practice of only reporting the outcome at the end of the study (EOS) might be replaced or complemented by a longitudinal summary that better reflects the clinical course of the disease. The area under the curve (AUC) is a summary measure that integrates serial assessments of a patient's endpoint over the duration of the study. We evaluated the utility of AUC as a summary measure for the analysis and reporting of two RA trials: (i) methotrexate combined with cyclosporine versus methotrexate and placebo in partial methotrexate responders in relatively late disease, and (ii) prednisone plus methotrexate plus sulfasalazine versus sulfasalazine alone in relatively early disease. We replicated the published results of each trial first using the conventional EOS and then AUC summaries. For each patient, the changes from baseline over time were transformed into a summary measure by calculating AUC using the trapezium rule and then standardizing it by the study duration. Using an approach similar to the index of responsiveness to change, we scaled treatment differences derived from EOS and AUC summary measures by their standard deviation of the control group. This signal-versus-noise ratio captures the treatment discrimination ability of each summary measure. Compared to EOS and within each treatment group, the AUC summary reported smaller effects (i.e., change from baseline) with reduced errors in the estimates. AUC measures preserved discriminant validity in treatment comparisons and reported smaller but more precise treatment effect estimates. In the COBRA trial with rapidly-acting medications, AUC seemed to be more sensitive than EOS to detect treatment difference. With slow acting medications and in relatively late disease patients as in the cyclosporine trial, EOS was more sensitive to detect treatment difference than was AUC. In this setting, AUC, however, still seemed to be more sensitive than EOS for the two responsive-to-change endpoints: tender joint counts and pain by visual analog scale. AUC integrates repeated assessments during the trial duration into summary measures. Compared to EOS, the report of RA trial results using AUC summary provides smaller estimates of treatment effects but with better precision. AUC summary is likely to preserve treatment group discrimination taking into account the appropriate onset and offset of the drug action. Trial reports using AUC summary have smaller effect sizes. For trials with long acting medications and short duration similar to the cyclosporine trial, AUC still preserves treatment discrimination but may not be as sensitive as EOS. The calculations of AUC require some additional work in the analysis of each endpoint.

[The influence of corticosteroid therapy on selected parameters of bone metabolism in children with nephrotic syndrome]

The aim of the study was to evaluate the influence of prednisone therapy on selected parameters of bone metabolism [carboxyterminal propeptide of type I procollagen (PICP), carboxyterminal pyridinoline crosslinked telopeptide of type I collagen (ICTP), alkaline phosphatase (AP), parathormone (PTH), and calciuria (Cau) in children with nephrotic syndrome. Twenty patients (aged 4-15 years, mean: 9.2 years) were treated with prednisone. Blood and urine samples were taken: T0--before prednisone treatment; T1--after two weeks of treatment with prednisone 1-2 mg/kg/24 h; T2--after two weeks of treatment with prednisone 1-2 mg/kg/48 h; T3--after 3 months of treatment with prednisone; T6--in 6th month of treatment with prednisone, at dose 0.2-0.4 mg/kg/48 h. Mean values of PICP, ICTP, AP concentration, and PICP/ICTP ratio found in the T1 period were significantly lower, and mean Cau value was higher in comparison to means of these parameters observed before steroid treatment. After two weeks of prednisone administered every 48 hours mean values of PICP, ICTP concentrations and PICP/ICTP ratio were significantly higher than in the T1 period of treatment. There were no significant differences in mean concentrations of PTH before and during everyday doses of prednisone therapy. Mean value of PTH concentration decreased significantly during T2 in comparison with T1 period of prednisone treatment. Our data demonstrate that short-term treatment with high daily doses of prednisone in children with nephrotic syndrome is associated with increase of calciuria and suppression of serum markers of type I collagen's turnover. Changes of PICP, ICTP, and PICP/ICTP ratio depend on a method of steroid administration. Decreased PICP/ICTP ratio during daily steroid treatment may indicate stronger inhibition of bone formation than bone resorption, but significance of PICP/ICTP ratio in later phases of treatment needs further studies. Present study suggests that prednisone influences bone metabolism directly rather than by stimulating the parathyroids.

Pharmacokinetics of intravenous methylprednisolone and oral prednisone in paediatric patients with inflammatory bowel disease during the acute phase and in remission

OBJECTIVE

The present study was undertaken to evaluate the influence of inflammatory bowel disease on the pharmacokinetics of intravenous methylprednisolone and prednisolone (after oral administration of prednisone).

PATIENTS

Twelve children with inflammatory bowel disease, aged 12.3 years were studied during the active phase and in remission. In 6 patients the disease responded to oral prednisone while 6 did not respond.

METHODS

During the acute phase, intravenous methylprednisolone (2 mg x kg(-1)) and oral prednisone (2 mg x kg(-1)) were administered in a random order and blood was sampled over 48 h. Prednisone (2 mg x kg(-1)) was readministered after remission. The concentrations of methylprednisolone and prednisolone were measured by high-pressure liquid chromatography.

RESULTS

During the acute phase, the systemic clearance of methylprednisolone was 0.98 (1 kg(-1) x h(-1)) and the elimination half-life was 1.67 h. The area under the plasma concentration-versus-time curve of prednisolone was 4.00 and 3.20 x mg x h x l(-1) respectively during the active disease and remission, while its elimination half-life was 3.51 h during the acute phase and 2.42 h in remission. There were no pharmacokinetic differences between the patients who responded or did not respond to oral treatment.

CONCLUSION

In children with inflammatory bowel disease, the initial response to corticosteroid therapy was not influenced by the pharmacokinetics of prednisolone and methylprednisolone. In addition, the pharmacokinetics of prednisolone was not modified by the inflammatory syndrome.

Prednisolone concentrations in cerebrospinal fluid after oral prednisone. Preliminary data

Penetration of prednisolone across the blood-brain barrier was studied in 17 patients (ten women and seven men) with a mean age of 64 +/- 17 years admitted for nerve root pain warranting a lumbar puncture. One blood sample and one cerebrospinal fluid sample were obtained concomitantly from each patient, two hours (n = 7), four hours (n = 5) or six hours (n = 5) after an oral dose of 40 mg of prednisone. Prednisolone was assayed in all samples using high performance liquid chromatography and its binding to plasma proteins was determined using ultrafiltration. Total plasma prednisolone levels declined over time from 597 +/- 174 ng/ml two hours post-dose to 422 +/- 106 ng/ml four hours post-dose and 250 +/- 85 ng/ml six hours post-dose. Plasma levels of free prednisolone were 95 +/- 21 ng/ml, 59 +/- 17 ng/ml, and 18 +/- 14 ng/ml, respectively, at the same time points. Prednisolone was detectable in all cerebrospinal fluid samples, in levels of 14 +/- 2 ng/ml after two hours, 29 +/- 9 ng/ml after four hours and 17 +/- 7 ng/ml after six hours. These data demonstrate that equilibration of plasma and cerebrospinal fluid levels is achieved after six hours.

A pharmacokinetic comparison of two oral liquid glucocorticoid formulations

To compare pharmacokinetics of liquid prednisolone and prednisone solutions and to assess relative bioavailability, six healthy adult men were administered 15 mg of each formulation. Blood samples were obtained and assayed for plasma prednisolone concentrations by high-performance liquid chromatography. Peak concentration was significantly higher with liquid prednisolone (mean +/- SD 430.3 +/- 62.5 vs 333.0 +/- 27.8 ng/ml, p = 0.013), with similar times to peak concentration. Prednisolone liquid gave higher concentrations at every time point (statistically significant for all except 0.25 hrs after the dose), resulting in a significantly greater total area under the curve (2029.8 +/- 246.9 vs 1633.3 +/- 221.1 ng/ml.hour, respectively, p = 0.002). Clearance was slower for prednisolone (128.3 +/- 15.1 vs 149.1 +/- 17.6 ml/min/1.73 m2, p = 0.01), and the relative bioavailability of the prednisolone liquid using prednisone liquid as the reference standard was 116 +/- 14%. Thus, prednisolone liquid has similar pharmacokinetic characteristics as prednisone liquid, with improved bioavailability.

Pulse glucocorticoid therapy. The 'big shot' revisited

The term pulse therapy refers to discontinuous intravenous infusion of very high doses of drugs over a short time. Methylprednisolone (and dexamethasone in some countries) is the glucocorticoid most frequently administered this way. Doses of each pulse are not standardized but are usually 10 to 20 mg per kilogram of body weight for methylprednisolone (250-1000 mg) and 2 to 5 mg per kilogram of body weight (50-200 mg) for dexamethasone. Single doses of 500 mg of methylprednisolone and 100 mg of dexamethasone are both considered equivalent to 625 mg of prednisone. These very high doses, sometimes termed megadoses, are usually given as intravenous infusions over 30 minutes to 1 hour daily or every other day for a total of 1 to 5 administrations. In most indications, pulse glucocorticoid therapy is accompanied and/or followed by the continuous administration of low- or intermediate-dose glucocorticoids and/or immunosuppressive agents.

Lack of pharmacokinetic interaction after administration of lansoprazole or omeprazole with prednisone

In a recently reported case, administration of omeprazole, a "proton pump" inhibitor, was temporally associated with the clinical relapse of pemphigus in a 44-year-old woman whose condition had been stabilized with a fixed dose of prednisone, suggesting the possibility of a drug interaction. This placebo-controlled, randomized, double-blind, three-period crossover study was conducted to evaluate and compare the pharmacokinetics of prednisolone after a single dose of prednisone given during multi-dose administration of lansoprazole or omeprazole. Lansoprazole (30 mg), omeprazole (40 mg), or placebo was administered once daily under fasted conditions for 7 days to healthy male volunteers. On the seventh day, a single dose of prednisone (40 mg) was administered concomitantly with the study medication, and plasma prednisolone concentrations were measured by high-performance liquid chromatography for 24 hours thereafter. Two weeks separated the first doses of each study period. Eighteen volunteers entered the study; pharmacokinetic data were evaluable for 15 participants. Safety data were evaluable for 16 participants in the lansoprazole/prednisone group; 17 in the omeprazole/ prednisone group; and 17 in the placebo/prednisone group. The pharmacokinetic parameters for prednisolone, including the maximum observed plasma concentration (Cmax), time to maximum plasma concentration (tmax), terminal-phase half-life (t1/2), and area under the concentration-time curve, were comparable for the three regimens. Adverse events (AEs) rated as possibly or probably drug related were reported by 50%, 24%, and 47% for subjects in the lansoprazole, omeprazole, and placebo treatment groups, respectively. Headache was the most common drug-related AE. No serious AEs were reported, and no subject withdrew from the study because of an AE. Concomitant administration of lansoprazole or omeprazole does not affect the absorption, biotransformation, or disposition of a single dose of prednisone. All three treatment regimens were well tolerated.

Pharmacodynamic modelling of the drug-induced downregulation of a beta 2-adrenoceptor mediated response and lack of restoration of receptor function after a single high dose of prednisone

Changes in beta 2-adrenoceptor function by chronic dosing of beta 2-mimetics and the possible influence of a single dose of prednisone have been studied as changes over time in the concentration-effect relationship of the beta 2-adrenoceptor agonist terbutaline. Hypokalaemia was used as the specific beta 2-adrenoceptor mediated effect. 8 healthy volunteers were given subcutaneous terbutaline 0.01 mg.kg-1 BW on 3 occasions over a 10-day experimental protocol: 1 Control experiment on Day 1; 2 After 7 days of oral terbutaline 5 mg t.i.d. (Day 8); and 3 After 8 days on oral terbutaline and 12 h after prednisone 100 mg orally (Day 10). The time course of the terbutaline concentrations and hypokalaemia was related using a pharmacokinetic-pharmacodynamic model. A sigmoid and a threshold Emax model were used to relate drug concentrations to effects. The oral terbutaline treatment caused a 35% increase in the distribution volume of SC terbutaline. After one week on oral terbutaline the concentration-effect relationship was shifted to the right and was steeper, with a higher EC50 of terbutaline and higher values for the apparent threshold concentration. These observations are compatible with a decrease in receptor numbers after 7 days of terbutaline in a system characterised by the presence of spare receptors. The data after prednisone pretreatment showed an apparent decline in the baseline plasma potassium concentrations that could be included in the Emax model. There was no change in the concentration-effect relationship 12 hours after prednisone.

The effect of grapefruit juice on cyclosporine and prednisone metabolism in transplant patients

OBJECTIVE

To estimate the effect of grapefruit juice on cyclosporine and prednisone metabolism.

METHODS

This was an open, placebo-controlled, two-way crossover study performed in the academic departments of clinical pharmacology and nephrology. On two study occasions, 12 kidney transplant patients with stable cyclosporine trough levels received either grapefruit juice or water every 3 hours for a period of 30 hours. The main outcome measures were peak concentration and time to peak, area under the concentration-time curve, the ratio of the area under the curve of the metabolites/area under the curve of the parent drug, terminal half-life, and 24-hour trough levels of cyclosporine.

RESULTS

Grapefruit juice increased the peak concentration of cyclosporine by 185 ng/ml (95% confidence interval, 60 to 310; p = 0.008). The ratio of the area under the curve of the metabolites of cyclosporine to the area under the curve of cyclosporine was reduced by 0.137 on the grapefruit day (95% confidence interval, -0.221 to -0.054; p = 0.004). After grapefruit juice, no significant changes were observed in the area under the curve and the time to peak of cyclosporine, prednisone, and prednisolone. Cyclosporine trough levels were unchanged by grapefruit juice.

CONCLUSIONS

Grapefruit juice inhibits the metabolism of cyclosporine for a brief period after administration, which may be explained by the inhibition of cytochrome P450 enzymes in the gut wall and to a lesser extent by inhibition of these enzymes in the liver. Grapefruit juice can be one of the factors leading to intraindividual variability in the pharmacokinetics of cyclosporine. Grapefruit juice had no significant effect on the metabolism of prednisone or prednisolone.

Pharmacokinetic interactions between zileuton and prednisone

A randomized double-blind placebo-controlled crossover study evaluated the effects of zileuton 600mg 4 time daily on the pharmacokinetics of prednisolone after a single 400mg oral dose of prednisone. the effects of the single prednisone dose on the steady-state pharmacokinetics of zileuton were also evaluated. Multiple doses of zileuton had no significant effects on mean peak plasma concentration (Cmax), time to Cmax(tmax), or area under the plasma concentration-time curve from 0 to infinity (AUC0-infinity) values for prednisolone after oral administration of prednisone 40mg. A slight but statistically significant increase in the mean half-life (t1/2) of prednisolone was detected with zileuton + prednisone administration compared with prednisone + placebo (from 2.8 to 2.9 hours); however, this change was of no clinical relevance. Mean Cmax values of zileuton after coadministration with prednisone were similar to those of zileuton alone. While the single 40mg dose of prednisone resulted in a slight but statistically significant decrease in the mean zileuton AUC value from 0 to 6 hours (AUC0-6) [from 23 to 20 mg/L/h] and a reduction in tMAX (from 2.3 to 1.7 hours), these results were not considered to be clinically significant. Therefore, it is considered that zileuton and prednisone may be coadministered with minimal risk of a clinically significant pharmacokinetic interaction.

Rifampin-induced nonresponsiveness of giant cell arteritis to prednisone treatment

Rifampin is an enzymatic inducer known to increase steroid metabolism. We studied two patients with giant cell arteritis in whom rifampin caused nonresponsiveness to prednisone treatment. A prednisone pharmacokinetics study was done. When rifampin-prednisone treatment must be used in giant cell arteritis, we propose increasing the prednisone dosage to 2 mg/kg per day.

11 beta-Hydroxysteroid dehydrogenase accounts for low prednisolone/prednisone ratios in the kidney

The purpose of the present investigation was to establish whether the ratio of the biologically active prednisolone to its inactive metabolite prednisone is determined by the 11 beta-hydroxysteroid dehydrogenase (11 beta-OHSD). The concentration ratios of prednisolone/prednisone assessed by HPLC 60 min after ip administration of prednisolone to rats were 0.8 in kidney, 5.5 in lung, 5.7 in spleen, 6.3 in heart, 7.1 in plasma, and 43 in liver. When prednisolone was injected together with glycyrrhetinic acid, an inhibitor of the 11 beta-OHSD, the ratios of prednisolone/prednisone in plasma and all tissues increased more than 10-fold. The plasma concentrations of glycyrrhetinic acid required to exhibit apparent half-maximal inhibitory effect of the 11 beta-OHSD were more than 7-fold higher for renal than for all other tissues. Thus, the 11 beta-OHSD accounts for low prednisolone/prednisone concentration ratios in renal tissue and, therefore, has to be considered a relevant determinant for the local intrarenal immunosuppressive effect of 11 beta-hydroxysteroids such as prednisolone.

Binding of the anti-inflammatory steroid deflazacort to glucocorticoid receptors in brain and peripheral tissues. In vivo and in vitro studies

Deflazacort (DFC) is a heterocyclic glucocorticoid with anti-inflammatory activity but with decreased side effects. In this study, we have evaluated the capacity of DFC and other glucocorticoids to reach the central nervous system (CNS) in vivo by measuring changes of [3H]dexamethasone (DEX) binding to glucocorticoid receptors (GR) in vitro. GR occupation was effected by DEX in the cerebral cortex, hippocampus, pituitary, liver and thymus, with DFC showing a similar profile except for the cerebral cortex. In contrast, corticosterone weakly occupied GR in the thymus, pituitary and hippocampus and methyl-prednisolone was active only in peripheral tissues. Furthermore, IC50 for DEX in vitro amounted to 15-17 nM in the hippocampus and liver, whereas IC50 for the active metabolite 21-deacetyl-DFC (21-OH-DFC) was 4 times higher. 21-OH-DFC bound to type II and was absent from type I GR. When tested in equipotent doses based on IC50 analysis, DFC and DEX similarly induced in vivo ornithine decarboxylase activity in hippocampus and liver, although body weight loss after chronic treatment was significantly less for DFC. The results show that DFC distributes on the CNS similarly to DEX, induces ornithine decarboxylase activity but presents less intensive catabolic effects, making it suitable for use as an anti-inflammatory steroid during chronic therapeutic regimes.