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.