Methylprednisolone pharmacokinetics, cortisol response, and adverse effects in black and white renal transplant recipients

Differential Glucocorticoid Responsiveness of Dialysis Patients’ Lymphocytes

Objectives

To evaluate in vitro glucocorticoid responsiveness of phytohemagglutinin (PHA)-stimulated lymphocytes from peritoneal dialysis (PO) patients compared to hemodialysis (HO) patients.

Design

Cross-sectional study of prevalent PO and HO patients and concurrent control subjects.

Setting

Urban outpatient dialysis unit.

Patients

20 HO, 14 PO, and 20 control subjects.

Measurements

Using standard lymphocyte culture techniques, the concentration of prednisolone (P) and methylprednisolone (MP) required to cause 50% inhibition (ICso) of the proliferative response to phytohemagglutinin (PHA) was determined from dose-response curves.

Results

There was considerable heterogeneity in the sensitivities of individual patients’ PBMC to glucocorticoid inhibition, especially those of HO patients’ cells to P. The mean: i: SO ICso for MP was significantly (p ≤ 0.001) lower than that for P in each cohort: PO 11 ± 5 vs. 34 ± 18 ng/mL; HO 22 ± 14 vs. 89 ± 43 ng/mL; control subjects 14 ± 11 vs. 55 ± 56 ng/mL. Interestingly, the ICSO for both P and MP was significantly higher in HO than in either PO or controls (ANOVA, P: F = 6.56, p = 0.003; MP: F = 3.77, p = 0.03), indicating decreased sensitivity of HO lymphocytes to both drugs. There were no significant differences in mean ICSO values for either P or MP between PO and controls. No correlations were found between ICSO for either P or MP and patient age, gender, duration of dialysis, serum creatinine, serum albumin, or parathyroid hormone level.

Conclusions

In vitro glucocorticoid responsiveness of dialysis patients’ lymphocytes appears to be influenced by dialysis modality, butthefactor(s) involved remains to be determined. Thegreater sensitivity of PO lymphocytes to both P and MP might result in better immunosuppression and less severe rejection after renal transplantation. MP may be particularly advantageous following renal transplantation for any patient manifesting relative or absolute in vitro resistance to P.

Intravenous pulse methylprednisolone for induction of remission in severe ANCA associated Vasculitis: a multi-center retrospective cohort study

Background

Intravenous pulse methylprednisolone (MP) is commonly included in the management of severe ANCA associated vasculitis (AAV) despite limited evidence of benefit. We aimed to evaluate outcomes in patients who had, or had not received MP, along with standard therapy for remission induction in severe AAV.

Methods

We retrospectively studied 114 consecutive patients from five centres in Europe and the United States with a new diagnosis of severe AAV (creatinine > 500 μmol/L or dialysis dependency) and that received standard therapy (plasma exchange, cyclophosphamide and high-dose oral corticosteroids) for remission induction with or without pulse MP between 2000 and 2013. We evaluated survival, renal recovery, relapses, and adverse events over the first 12 months.

Results

Fifty-two patients received pulse MP in addition to standard therapy compared to 62 patients that did not. There was no difference in survival, renal recovery or relapses. Treatment with MP associated with higher risk of infection during the first 3 months (hazard ratio (HR) 2.7, 95%CI [1.4–5.3], p = 0.004) and higher incidence of diabetes (HR 6.33 [1.94–20.63], p = 0.002), after adjustment for confounding factors.

Conclusions

The results of this study suggest that addition of pulse intravenous MP to standard therapy for remission induction in severe AAV may not confer clinical benefit and may be associated with more episodes of infection and higher incidence of diabetes.

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1226-0) contains supplementary material, which is available to authorized users.

Gender-based personalized pharmacotherapy: a systematic review

PURPOSE

In general, male and female are prescribed the same amount of dosage even if most of the cases female required less dosage than male. Physicians are often facing problem on appropriate drug dosing, efficient treatment, and drug safety for a female in general. To identify and synthesize evidence about the effectiveness of gender-based therapy; provide the information to patients, providers, and health system intervention to ensure safety treatment; and minimize adverse effects.

METHODS

We performed a systematic review to evaluate the effect of gender difference on pharmacotherapy. Published articles from January 1990 to December 2015 were identified using specific term in MEDLINE (PubMed), EMBASE, and the Cochrane library according to search strategies that strengthen the reporting of observational and clinical studies.

RESULTS

Twenty-six studies fulfilled the inclusion criteria for this systematic review, yielding a total of 6309 subjects. We observed that female generally has a lower the gastric emptying time, gastric PH, lean body mass, and higher plasma volume, BMI, body fat, as well as reduce hepatic clearance, difference in activity of Cytochrome P450 enzyme, and metabolize drugs at different rate compared with male. Other significant factors such as conjugation, protein binding, absorption, and the renal elimination could not be ignored. However, these differences can lead to adverse effects in female especially for the pregnant, post-menopausal, and elderly women.

CONCLUSION

This systematic review provides an evidence for the effectiveness of dosage difference to ensure safety and efficient treatment. Future studies on the current topic are, therefore, recommended to reduce the adverse effect of therapy.

Metabolic consequences of modern immunosuppressive agents in solid organ transplantation

Among other factors, sophistication of immunosuppressive (IS) regimen accounts for the remarkable success attained in the short- and medium-term solid organ transplant (SOT) survival. The use of steroids, mycophenolate mofetil and calcineurin inhibitors (CNI) have led to annual renal graft survival rates exceeding 90% in the last six decades. On the other hand, attrition rates of the allograft beyond the first year have remained unchanged. In addition, there is a persistent high cardiovascular (CV) mortality rate among transplant recipients with functioning grafts. These shortcomings are in part due to the metabolic effects of steroids, CNI and sirolimus (SRL), all of which are implicated in hypertension, new onset diabetes after transplant (NODAT), and dyslipidemia. In a bid to reduce the required amount of harmful maintenance agents, T-cell-depleting antibodies are increasingly used for induction therapy. The downsides to their use are greater incidence of opportunistic viral infections and malignancy. On the other hand, inadequate immunosuppression causes recurrent rejection episodes and therefore early-onset chronic allograft dysfunction. In addition to the adverse metabolic effects of the steroid rescue needed in these settings, the generated proinflammatory milieu may promote accelerated atherosclerotic disorders, thus setting up a vicious cycle. The recent availability of newer agent, belatacept holds a promise in reducing the incidence of metabolic disorders and hopefully its long-term CV consequences. Although therapeutic drug monitoring as applied to CNI may be helpful, pharmacodynamic tools are needed to promote a customized selection of IS agents that offer the most benefit to an individual without jeopardizing the allograft survival.

Pharmacokinetics and Pharmacodynamic Response of Methylprednisolone in Premenopausal Renal Transplant Recipients

Chronic glucocorticoid therapy is prescribed in renal transplant recipients according to empiric dose-tapering schedules, which assume a similar pharmacologic response in men and women. The study objectives were (a) to compare the pharmacokinetics of methylprednisolone in premenopausal renal transplant recipients with previously studied male counterparts and (b) to describe the pharmacodynamic response of the hypothalamic-pituitary-adrenal axis during chronic steroid therapy. Thirteen stable premenopausal subjects (ages 30 to </=49 years) receiving chronic glucocorticoid therapy were evaluated for methylprednisolone, cortisol, and adrenocorticotropin hormone (ACTH) over 24 hours after an intravenous infusion of methylprednisolone sodium succinate. Most patients were evaluated during the luteal phase of the menstrual cycle. Pharmacokinetic parameters of methylprednisolone with cortisol and ACTH responses were determined. Results were compared to counterpart male subjects who participated in a prior study. The total clearance of methylprednisolone for the female subjects was 15.6 +/- 5.99 L/h compared to the males with 21.5 +/- 8.67 L/h (P <.05). When normalized for total or lean body weight, no significant difference was noted (P =.614). A 3-fold interpatient variation in weight-adjusted clearance was noted for female subjects. Dose-normalized methylprednisolone a AUC was greater in women (66.1 +/- 19.8 ng*h/mL) than men (46.4 +/- 19.7 ng*h/mL) (P =.174). Total cortisol AUC was not different between groups (P =.599). Despite chronic steroid therapy, 9 of 13 women had a normal cortisol profile and an ACTH AUC of 299 +/- 102 pg*h/mL. It was concluded that methylprednisolone clearance in women was significantly slower compared to men. When drug clearance was normalized for total and lean body weight, no gender difference was noted. These findings are in contrast to prior data indicating a more rapid methylprednisolone clearance in healthy women. These findings suggest that doses of glucocorticoids should be prescribed on a milligram/kilogram basis instead of empiric dosing schedules.

Immunotherapy in elderly transplant recipients: a guide to clinically significant drug interactions

Currently, >50% of candidates for solid organ transplantation in Europe and the US are aged >50 years while approximately 15% of potential recipients are aged >or=65 years. Elderly transplant candidates are characterized by specific co-morbidity profiles that compromise graft and patient outcome after transplantation. The presence of coronary artery or peripheral vascular disease, cerebrovascular disease, history of malignancy, chronic obstructive lung disease or diabetes mellitus further increases the early post-transplant mortality risk in elderly recipients, with infections and cardiovascular complications as the leading causes of death. Not only are elderly patients more prone to developing drug-related adverse effects, but they are also more susceptible to pharmacokinetic and pharmacodynamic drug interactions because of polypharmacy. The majority of currently used immunosuppressant drugs in organ transplantation are metabolized by cytochrome P450 (CYP) or uridine diphosphate-glucuronosyltransferases and are substrates of the multidrug resistance (MDR)-1 transporter P-glycoprotein, the MDR-associated protein 2 or the canalicular multispecific organic anion transporter, which predisposes these immunosuppressant compounds to specific interactions with commonly prescribed drugs. In addition, important drug interactions between immunosuppressant drugs have been identified and require attention when choosing an appropriate immunosuppressant drug regimen for the frail elderly organ recipient. An age-related 34% decrease in total body clearance of the calcineurin inhibitor ciclosporin was observed in elderly renal recipients (aged >65 years) compared with younger patients, while older recipients also had 44% higher intracellular lymphocyte ciclosporin concentrations. Similarly, using a Bayesian approach, an inverse relationship was noted between sirolimus clearance and age in stable kidney recipients. Ciclosporin and tacrolimus have distinct pharmacokinetics, but both are metabolized by intestinal and hepatic CYP3A4/3A5 and transported across the cell membrane by P-glycoprotein. The most common drug interactions with ciclosporin are therefore also observed with tacrolimus, but the two drugs do not interact identically when administered with CYP3A inhibitors or inducers. The strongest effects on calcineurin-inhibitor disposition are observed with azole antifungals, macrolide antibacterials, rifampicin, calcium channel antagonists, grapefruit juice, St John's wort and protease inhibitors. Drug interactions with mycophenolic acids occur mainly through inhibition of their enterohepatic recirculation, either by interference with the intestinal flora (antibacterials) or by limiting drug absorption (resins and binders). Rifampicin causes a reduction in mycophenolic acid exposure probably through induction of uridine diphosphate-glucuronosyltransferases. Proliferation signal inhibitors (PSIs) such as sirolimus and everolimus are substrates of CYP3A4 and P-glycoprotein and have a macrolide structure very similar to tacrolimus, which explains why common drug interactions with PSIs are comparable to those with calcineurin inhibitors. Ciclosporin, in contrast to tacrolimus, inhibits the enterohepatic recirculation of mycophenolic acids, resulting in significantly lower concentrations and hence risk of underexposure. Therefore, when switching from tacrolimus to ciclosporin and vice versa or when reducing or withdrawing ciclosporin, this interaction needs to be taken into account. The combination of ciclosporin with PSIs requires dose reductions of both drugs because of a synergistic interaction that causes nephrotoxicity when left uncorrected. Conversely, when switching between calcineurin inhibitors, intensified monitoring of PSI concentrations is mandatory. Increasing age is associated with structural and functional changes in body compartments and tissues that alter absorptive capacity, volume of distribution, hepatic metabolic function and renal function and ultimately drug disposition. While these age-related changes are well-known, few specific effects of the latter on immunosuppressant drug metabolism have been reported. Therefore, more clinical data from elderly organ recipients are urgently required.

A Comparison of the Pharmacokinetics and Pharmacodynamics of Docetaxel between African-American and Caucasian Cancer Patients: CALGB 9871

PURPOSE

Increased clearance of drugs, such as oral cyclosporine, that are CYP3A and/or ABCB1 (P-gp/MDR1) substrates was reported in African-American compared with Caucasian patients. We hypothesized that the pharmacokinetics and pharmacodynamics of docetaxel, an i.v. administered cytotoxic and substrate for CYP3A4, CYP3A5, and ABCB1, would differ between African-American and Caucasian patients.

EXPERIMENTAL DESIGN

We investigated population pharmacokinetics and pharmacodynamics and the pharmacogenetics of CYP3A4, CYP3A5, and ABCB1 in African-American and Caucasian cancer patients who received docetaxel 75 or 100 mg/m(2) as a 1-h i.v. infusion. Plasma docetaxel concentrations were measured by high-performance liquid chromatography. Clinical toxicity and absolute neutrophil count (ANC) were monitored on days 8, 15, and 22 postadministration of docetaxel. Using a limited sampling strategy and nonlinear mixed-effects modeling, each patient's docetaxel clearance was estimated. Genotyping for known polymorphisms in CYP3A4, CYP3A5, and ABCB1 was done.

RESULTS

We enrolled 109 patients: 40 African-Americans (26 males; 14 females), with a median age of 61 years (range, 29-73), and 69 Caucasians (43 males; 26 females), with a median age of 63 years (range, 38-81). There was no difference in the geometric mean docetaxel clearance between African-American patients [40.3 L/h; 95% confidence interval (95% CI), 19.3-84.1] and Caucasian patients (41.8 L/h; 95% CI, 22.0-79.7; P = 0.6). We observed no difference between African-American and Caucasian patients in the percentage decrease in ANC nor were docetaxel pharmacokinetic parameters related to the genotypes studied.

CONCLUSIONS

Docetaxel clearance and its associated myelosuppression were similar in African-American and Caucasian cancer patients.

Does pharmacogenetics have the potential to allow the individualisation of immunosuppressive drug dosing in organ transplantation?

The immunosuppressive drugs used in organ transplantation have a narrow therapeutic index, with rejection occurring as a consequence of underdosing and infection, malignancy and a number of drug-specific side effects with excessive dosing. Significant heterogeneity in the dose of drug required to achieve therapeutic blood concentrations adds to the complexity of the problem, which has been partly resolved by therapeutic drug monitoring. Single nucleotide polymorphisms have been identified in genes encoding metabolic enzymes, drug efflux pumps and drug targets for most of the drugs in widespread use. A pharmacogenetic approach to immunosuppressive drug prescribing remains to be tested. Based on current evidence, the most promising strategy would be use of the cytochrome P450 3A5 expressor genotype to guide initial dosing with tacrolimus.

Safety of low dose glucocorticoid treatment in rheumatoid arthritis: published evidence and prospective trial data

Adverse effects of glucocorticoids have been abundantly reported. Published reports on low dose glucocorticoid treatment show that few of the commonly held beliefs about their incidence, prevalence, and impact are supported by clear scientific evidence. Safety data from recent randomised controlled clinical trials of low dose glucocorticoid treatment in RA suggest that adverse effects associated with this drug are modest, and often not statistically different from those of placebo.

Developments in Glucocorticoid Therapy

Recent evidence for a disease-modifying potential of low-dose glucocorticoids (GCs) in the treatment of rheumatoid arthritis has renewed the debate on the risk benefit ratio with this therapy. Two recent developments are described that might have a positive influence on these risk benefit ratios. One is the improvement in new GC compounds--designer GCs, alterations in bioactivity, and alterations in formulations. The other is a better understanding and management of the toxicity of GCs.

Will tomorrow's medicines work for everyone?

Throughout much of the world, 'race' and 'ethnicity' are key determinants of health. For example, African Americans have, by some estimates, a twofold higher incidence of fatal heart attacks and a 10% higher incidence of cancer than European Americans, and South Asian- or Caribbean-born British are approximately 3.5 times as likely to die as a direct result of diabetes than are British of European ancestry. The health care that people receive also depends on 'race' and 'ethnicity'. African Americans are less likely to receive cancer-screening services and more likely to have late-stage cancer when diagnosed than European Americans. Health disparities such as these are one of the greatest social injustices in the developed world and one of the most important scientific and political challenges.

A review and assessment of potential sources of ethnic differences in drug responsiveness

The International Conference on Harmonization (ICH) E5 guidelines were developed to provide a general framework for evaluating the potential impact of ethnic factors on the acceptability of foreign clinical data, with the underlying objective to facilitate global drug development and registration. It is well recognized that all drugs exhibit significant inter-subject variability in pharmacokinetics and pharmacologic response and that such differences vary considerably among individual drugs and depend on a variety of factors. One such potential factor involves ethnicity. The objective of the present work was to perform an extensive review of the world literature on ethnic differences in drug disposition and responsiveness to determine their general significance in relation to drug development and registration. A few examples of suspected ethnic differences in pharmacokinetics or pharmacodynamics were identified. The available literature, however, was found to be heterologous, including a variety of study designs and research methodologies, and most of the publications were on drugs that were approved a long time ago.

Pharmacokinetics of an everolimus-cyclosporine immunosuppressive regimen over the first 6 months after kidney transplantation

The pharmacokinetics of everolimus were characterized over the first 6 months post transplant in 731 patients receiving either 0.75 or 1.5 mg bid everolimus in addition to cyclosporine and corticosteroids. Pharmacokinetic data consisted of 4014 everolimus trough concentrations (Cmin) obtained in all patients and 659 area under the concentration-time curve (AUC) -profiles obtained at months 2, 3, and 6 in a subset of 261 patients. Cmins averaged 4.3 +/- 2.4 and 7.2 +/- 4.2 ng/mL at 0.75 and 1.5 mg bid, indicating a 20% under-proportionality at the upper dose level. Cmins were 19-34% lower in the first month compared with months 2 through 6-values. AUC was dose-proportional and stable over time, averaging 77 +/- 32 and 136 +/- 57 ng.h.mL-1 at the two dose levels. Within- and between-patient variability in AUC were 27% and 31%, respectively. There was no influence of sex, age (16-66 years), or weight (42-132 kg) on AUC. Everolimus exposure was significantly lower by an average 20% in blacks. Everolimus exposure was relatively stable over the first 6 months post transplant, with no major departure from dose-proportionality over the therapeutic dose range. Weight-adjusted dosing (mg/kg) does not appear warranted. Black patients may have lower bioavailability and/or higher clearance of everolimus compared with white patients.

Ethnicity greatly influences cytokine gene polymorphism distribution

Polymorphisms in the regulatory regions of cytokine genes are associated with high and low cytokine production and may modulate the magnitude of alloimmune responses following transplantation. Ethnicity influences allograft half-life and the incidence of acute and chronic rejection. We have questioned whether ethnic-based differences in renal allograft survival could be due in part to inheritance of cytokine polymorphisms. To address that question, we studied the inheritance patterns for polymorphisms in several cytokine genes (IL-2, IL-6, IL-10, TNF-alpha, TGF-beta, and IFN-gamma) within an ethnically diverse study population comprised of 216 Whites, 58 Blacks, 25 Hispanics, and 31 Asians. Polymorphisms were determined by allele-specific polymerase chain reaction and restriction fragment length analysis. We found striking differences in the distribution of cytokine polymorphisms among ethnic populations. Specifically, significant differences existed between Blacks and both Whites and Asians in the distribution of the polymorphic alleles for IL-2. Blacks, Hispanics and Asians demonstrated marked differences in the inheritance of IL-6 alleles and IL-10 genotypes that result in high expression when compared with Whites. Those of Asian descent exhibited an increase in IFN-gamma genotypes that result in low expression as compared to Whites. In contrast, we did not find significant ethnic-based differences in the inheritance of polymorphic alleles for TNF-alpha. Our results show that the inheritance of certain cytokine gene polymorphisms is strongly associated with ethnicity. These differences may contribute to the apparent influence of ethnicity on allograft outcome.

Prednisolone pharmacokinetics and pharmacodynamics in relation to sex and race

Prednisolone pharmacokinetics (PK) and pharmacodynamics (PD) were investigated in relation to sex and race in white males, black males, white females, and black females (n = 8/group) after a single oral dose (0.27 mg/kg) of prednisone. The study consisted of baseline and prednisone phases with 32-hour sampling in each phase. Women were studied during the luteal phase of their menstrual cycle. Total and free plasma prednisolone concentrations were assayed by HPLC and ultrafiltration, and pharmacokinetic data were analyzed by compartmental fitting using WinNonlin. Plasma cortisol concentrations were assayed by HPLC; T-helper, T-suppressor lymphocyte, and neutrophil cell counts were determined by FACS and hemocytometry, and these pharmacodynamic data were evaluated by basic and extended indirect response models using ADAPT II. Total body weight-normalized free prednisolone oral clearance and apparent volume of distribution were higher in men compared with women, regardless of race (by 22% in whites and 40% in blacks for oral clearance, p < 0.01; by32% in whites and 38% in blacks for apparent volume of distribution, p < 0.01). The 50% inhibitory concentration (IC50) values for T-suppressor cell-trafficking inhibition were higher in whites than in blacks, regardless of sex (by 125% in men and 208% in women, p < 0.01). The IC50 or SC50 values for effects of prednisolone on cortisol secretion and T-helper lymphocyte or neutrophil trafficking were not statistically different between men and women, blacks and whites. The findings of this study suggest that there are some prednisolone PK/PD differences related to sex and race. However, these differences do not suggest the need for dosage adjustments, and additional experiments with repeat dosing are needed to fully evaluate the clinical implication of these findings.

Recommendations for the outpatient surveillance of renal transplant recipients. American Society of Transplantation

Many complications after renal transplantation can be prevented if they are detected early. Guidelines have been developed for the prevention of diseases in the general population, but there are no comprehensive guidelines for the prevention of diseases and complications after renal transplantation. Therefore, the Clinical Practice Guidelines Committee of the American Society of Transplantation developed these guidelines to help physicians and other health care workers provide optimal care for renal transplant recipients. The guidelines are also intended to indirectly help patients receive the access to care that they need to ensure long-term allograft survival, by attempting to systematically define what that care encompasses. The guidelines are applicable to all adult and pediatric renal transplant recipients, and they cover the outpatient screening for and prevention of diseases and complications that commonly occur after renal transplantation. They do not cover the diagnosis and treatment of diseases and complications after they become manifest, and they do not cover the pretransplant evaluation of renal transplant candidates. The guidelines are comprehensive, but they do not pretend to cover every aspect of care. As much as possible, the guidelines are evidence-based, and each recommendation has been given a subjective grade to indicate the strength of evidence that supports the recommendation. It is hoped that these guidelines will provide a framework for additional discussion and research that will improve the care of renal transplant recipients.

Ethnic differences in clinical response to corticosteroid treatment of acute renal allograft rejection

BACKGROUND

Limited in vitro data suggest that African-Americans exhibit greater resistance to corticosteroids than do non-African-American transplant recipients. However, ethnic differences in clinical response to corticosteroids for treatment of acute rejection have not been investigated previously. The purpose of this study was to evaluate the clinical response to corticosteroid treatment for acute rejection in both African-American and non-African-American renal allograft recipients.

METHODS

We retrospectively reviewed the medical records of 497 consecutive renal allograft recipients to identify patients who had received corticosteroids as initial treatment of acute rejection. One hundred and twenty patients who received corticosteroids for treatment of acute rejection were evaluated in this analysis. The study population was divided into two groups: the African-American group (n=73) and non-African-American group (n=47). All acute rejection episodes were documented by biopsy and were classified as mild-moderate histologically. Corticosteroid therapy consisted of either methylprednisolone, 500 mg intravenously for 3 days, or oral prednisone, 2 mg/kg/day rapidly tapered over 3 weeks.

RESULTS

Twenty-six percent (26%) of African-Americans were considered corticosteroid treatment failures compared to an 8.0% failure rate among non-African-Americans (P<0.05). One-year graft survival was 78% in African-American versus 96% in non-African-American (P<0.05). Among African-American and non-African-American recipients, 1-year patient survival rates were 97% and 100, respectively (P=NS).

CONCLUSIONS

African-American patients exhibit higher failure rates with corticosteroid treatment of acute rejection. Alternative anti-rejection therapies may need to be considered for this "high-risk" patient population to improve long-term graft survival.

Histological outcome of acute cellular rejection in kidney transplantation after treatment with methylprednisolone

BACKGROUND

Several studies comparing the response of acute cellular rejection (ACR) episodes to different corticosteroid regimens have been conducted. However, in most of them, the histological evaluation of the infiltrate and its correlation with clinical response was not studied. The clinical and histological outcomes of 37 episodes of ACR treated with methylprednisolone (MP) were studied, with the aim to determine how long the infiltrate takes to be cleared after therapy.

METHODS

A total of 37 patients with biopsy-proven ACR were treated with 8 or 16 mg of MP/kg/day. Allograft biopsies were repeated at 5 and 10 days after the end of corticotherapy. Clinical and histological outcomes were compared.

RESULTS

Six patients were excluded; 15 (48.4%) patients responded to therapy; the mean serum creatinine of these patients reached normal levels in the 2 weeks that followed treatment. Nine patients (60%) of this group had signs of ACR on biopsies done 5 days after corticotherapy, and four (26.7%) maintained them on the 10th day. Among 16 patients with no clinical response, none reached normal serum creatinine levels; 15 (93.7%) had signs of rejection 5 days after treatment and maintained them on the 10th day. Histological signs of ACR disappeared in 73.3% of patients with clinical response 10 days after therapy, but in only 6.3% of patients with no response (P=0.001).

CONCLUSIONS

Biopsies performed 5 days after treatment show a high incidence of features of ACR; such features take on average 10 days to disappear in nearly 75% of cases with successful therapy with MP.

Influence of race or ethnicity on pharmacokinetics of drugs

Review of the current literature on racial differences in pharmacokinetics of drugs supports the premise that only pharmacokinetic processes which are biologically or biochemically mediated have the potential to exhibit differences between racial or ethnic groups. Thus, the pharmacokinetic factors which can be expected to potentially exhibit racial differences are (1) bioavailability for drugs which undergo gut or hepatic first-pass metabolism, (2) protein binding, (3) volume of distribution, (4) hepatic metabolism, and (5) renal tubular secretion. Absorption (unless active), filtration at the glomerulus, and passive tubular reabsorption would not be expected to exhibit racial differences. As is evident from this review, there are relatively few drugs for which there is information on ethnic or racial differences in pharmacokinetics. Thus it is often necessary to try to predict whether such differences might exist. Taking into consideration the above factors and evaluation of the pharmacokinetic characteristics of the drug, it should be possible to identify those drugs most likely to exhibit differences in their pharmacokinetics. For example, a drug which is eliminated entirely by the kidneys through filtration and reabsorption and is not highly bound to plasma proteins (or is bound to albumin) is highly unlikely to exhibit racial differences in its kinetics. Conversely, a drug which undergoes significant gut and/or hepatic first-pass metabolism and is highly bound to AGP is much more likely to exhibit kinetic differences between racial groups. A discussion of the impact of racial differences in kinetics on drug response or racial differences in drug efficacy, toxicity, or pharmacodynamics (concentration-response relationship) is beyond the scope of this review. However, a number of the papers described above also evaluated differences in pharmacodynamics or response. Among the comparisons of Chinese and Caucasians, these include the papers on propranolol, morphine, nifedipine, triazolam, diazepam, and omeprazole. For those studies comparing differences in blacks and Caucasians, responses or pharmacodynamics were also determined in the studies of propranolol, trimazosin, and methylprednisolone. Interested readers are also referred to the review by Wood and a more recent review by Kitler for additional discussion of ethnic/racial differences in pharmacodynamics/drug response.

Immunosuppressive therapy in high-risk transplant patients: dose-dependent efficacy of mycophenolate mofetil in African-American renal allograft recipients. U.S. Renal Transplant Mycophenolate Mofetil Study Group

BACKGROUND

Numerous studies have demonstrated that renal allograft survival is reduced in African-Americans (AAs). This posthoc racial subgroup analysis (AAs vs. non-AAs) tested whether mycophenolate mofetil (MMF) might have favorable implications for the treatment of AA renal allograft recipients.

METHODS

Patients received a triple therapy regimen of corticosteroids, cyclosporine, and azathioprine (AZA) 1-2 mg/kg/day, MMF 2 g/day (MMF 2 g), or MMF 3 g/day (MMF 3 g).

RESULTS

AAs in the AZA group had the highest biopsy-proven rejection/treatment failure (BPR/TF) rate (57.5% vs. 43.5% for non-AAs). AAs in the MMF 3 g group showed a significant reduction in BPR/TF (57.5% vs. 24.2%, P=0.0008). BPRs were more frequent for AAs in either the AZA (47.5%) or MMF 2 g group (31.8%) than in the MMF 3 g group (12.1%), whereas rejections were reduced for non-AAs receiving either MMF dosage (AZA, 35.5%; MMF 2 g, 15.7%; MMF 3 g, 18.8%). AAs in the AZA group experienced BPR/TF earlier than AAs in the MMF 3 g group (median onset at 64 days vs. > 183 days, P=0.0012). But AAs in the MMF 3 g experienced BPR/TF the latest among the six subgroups of treatment and race. AAs had more severe rejection episodes and higher serum creatinine levels at 6 months after transplant, regardless of treatment group.

CONCLUSIONS

Dose-dependent prevention of acute rejection in AAs is best afforded by a dosage of MMF at 3 g/day, whereas 2 g/day provides a superior benefit/risk ratio for non-AAs. MMF at 3 g/day thus provides an improvement over conventional immunosuppressive strategies in reducing the frequency of acute rejections in this immunologically high-risk group.

Clinical pharmacokinetic considerations in the elderly. An update

There are a number of areas in which advances have been made over the last few years in the area of pharmacokinetics in the elderly. There is increasing understanding of the diversity of cytochrome P450s (CYP) and the variability of the age-related decline in CYP activity. This has helped to explain some of the interindividual variability in drug metabolism with age. The importance of ethnic differences has emerged, but specific work is needed in this area in the elderly. Differences in the handling of chiral compounds has been reported but as yet no clinically important findings that may lead to a change in clinical practice have emerged. The emerging importance of extrahepatic drug metabolism, especially in the intestine, has added a new complexity to our understanding of pharmacokinetics. The issue of frailty is also discussed in this article. Whether it will be of value at the bedside has yet to emerge. Nonetheless, as a concept, recent data has supported its potential use to define those more at risk of clinically meaningful pharmacokinetic alterations. Other advances have included the appreciation that selectivity in induction and inhibition in the elderly are due to the existence of multiple CYP forms. Similarly, the role of these various enzymes in disease is also improving our clinical understanding, as exemplified in Parkinson's disease.

Cortisol pharmacodynamics after methylprednisolone administration in young and elderly males

Glucocorticoids are commonly prescribed in the elderly on an empiric basis with little consideration for the age-related alterations in pharmacologic response. The objectives of this study were to compare the effect of methylprednisolone on cortisol patterns in elderly and young healthy men, to define the relationship between pharmacokinetic parameters of methylprednisolone and pharmacodynamics of cortisol in the elderly and young men. Seven healthy, elderly males (69-82 years old) and five healthy, young males (24-37 years old) participated in a 24-hour pharmacodynamic trial with randomized assignment to a control period (Phase 1) and a methylprednisolone period (Phase II). Serial blood samples were obtained throughout both study periods. Cortisol measurements included the total area under the concentration-time curve (AUC), return AUC, and suppression ratio. During Phase I, a circadian pattern was noted in both groups. After exposure to methylprednisolone (Phase II), a linear decline in serum concentrations of cortisol was observed in both groups. The return AUC of cortisol (425 +/- 357 ng.hr/mL [elderly] versus 854 +/- 216 ng.mL [young]) and the total AUC 764 +/- 340 ng.h/mL [elderly] versus 1,230 +/- 258 ng.hr/mL [young]) were significantly lower in the older men. In addition, a significant decline in total AUC and nadir concentration of cortisol from Phase I to Phase II was noted within both groups. The suppression ratio was significantly greater in the elderly men (mean, 0.38 versus 0.58 in young), which indicates a greater degree of adrenal suppression after administration of methylprednisolone. Exposure to methylprednisolone, as measured by AUC, was 554 +/- 215 ng.hr/kg (elderly) and 389 +/- 102 ng.hr/kg (young). The greater exposure to methylprednisolone noted in the elderly yielded significant combined correlations for both groups with AUC, return AUC, and suppression ratio of cortisol. A more significant response of cortisol to the exogenous glucocorticoid was apparent in the elderly men. In addition, a slower clearance of methylprednisolone was noted in the elderly group compared with their young counterparts. The effect of reduced clearance of methylprednisolone on the suppression ratio indicates the interrelationship between the disposition of a single dose of an exogenous glucocorticoid and response patterns of cortisol.

Suppression of lymphocyte interleukin-2 receptor expression by glucocorticoids, cyclosporine, or both

Although glucocorticoids and cyclosporine are frequently used to treat patients with various types of glomerulopathy, clinical responses to treatment vary considerably. Considerable interindividual heterogeneity in the suppressive effects of glucocorticoids on lymphocyte proliferation in vitro has been previously reported, suggesting that differences in the pharmacodynamic responsiveness of the immune system to these agents might be an important determinant of how well an individual patient responds to treatment. It also has been shown that methylprednisolone is significantly more suppressive than prednisolone. To identify cellular mechanisms by which these drugs act, a study of the suppressive effects of prednisolone, methylprednisolone, and cyclosporine on lymphocyte proliferation and the expression of the cell surface receptor for interleukin-2 (IL-2R) was conducted using phytohemagglutin-stimulated peripheral blood mononuclear cells (PBMCs) from 13 patients with glomerulopathy and 12 control subjects. Heterogeneity among individuals in both parameters of lymphocyte responsiveness to these drugs was again found, and the significantly greater suppressive effect of methylprednisolone was confirmed for both proliferation and IL-2R expression in patients and control subjects. Cyclosporine alone was moderately suppressive. For most individuals, the greatest degree of suppression occurred when cells were exposed to both cyclosporine and glucocorticoid. Further studies are being conducted to determine whether pretreatment assessment of in vitro lymphocyte responsiveness has any predictive value regarding therapeutic efficacy of each drug in individual patients and to identify of those patients likely to require a more intensive or multidrug immunosuppressive regimen.

Lymphocyte responsiveness to glucocorticoids, cyclosporine, or both

The reason why some patients with glomerular diseases respond to steroid treatment and others do not remains obscure, and it is not possible to prospectively evaluate the probability of response in individual patients. One factor that might contribute to the clinical response to treatment could be the relative sensitivity of a patient's immune system to the suppressive effects of steroids or other immunosuppressive agents. To evaluate this possibility, phytohemagglutinin (PHA)-stimulated peripheral blood mononuclear cells (PBMC) from 16 patients with various biopsy-proven glomerulopathies were cultured with prednisolone or methylprednisolone in final concentrations of 10(-5) to 10(-8) mol/L. From the dose-response curves, the concentration of steroid required to cause 50% inhibition (IC50) of the PHA-induced proliferative response was determined. The PBMC from 10 patients also were cultured with 400 ng/mL cyclosporine both alone and with 10(-7) mol/L steroid, and the inhibitory effects were calculated. There was considerable heterogeneity in the sensitivities of individual patients to steroid inhibition, and the mean +/- SEM IC50 was significantly lower for methylprednisolone than for prednisolone. Cyclosporine caused 50% or greater inhibition in 6 of the 10 patients but had < 10% inhibitory effect in 2 patients. In most patients studied, cyclosporine plus steroid was significantly more inhibitory than cyclosporine alone, but the combination was usually no more effective than 10(-7) mol/L methylprednisolone alone. These results are consistent with the hypothesis that differences in the sensitivity of individual patient's immune systems to the immunosuppressive effects of steroids and cyclosporine might contribute to differences in their clinical responsiveness to treatment.

The results of 1009 kidney transplantations performed in Hungary

Kidney transplantation is a widely used method throughout the world for the treatment of end-stage renal disease. Following the pioneering work of Szeged Medical University Hospital and Miskolc District General Hospital, the first successful kidney transplantation in Hungary was performed at the Department of Transplantation and Surgery at Semmelweis Medical University on November 16, 1973. This patient is still alive with a functioning kidney graft after 21 years. We report herein our review of the global results of Hungarian kidney transplantation. Hungary is a medium-developed country with a population of over 10 million where the gross national product is about 4000 U.S. dollars per person per year. In Hungary there are 49 dialysis centers, 4 immunological laboratories, and 4 transplantation centers.

Differences in the hypothalamic-pituitary-adrenal axis of black girls and white girls

After intravenous administration of ovine corticotropin-releasing hormone (CRH), the plasma corticotropin (ACTH) concentrations of adult black women and men are approximately twice as high as those of adult white women and men; however, there are no corresponding differences in cortisol response. To determine whether these differences in ACTH secretion are also present in prepubertal and early pubertal girls, we studied the hypothalamic-pituitary-adrenal axis of 19 black and 19 white girls of normal weight (age 7 to 10 years) who were matched for body mass index, age, and socioeconomic status. Measures of cortisol's effects, including waist circumference, waist/hip ratio, and fasting insulin and glucose levels, were obtained and related to the ACTH and cortisol responses to 1 micrograms/kg CRH. There were no racial differences in waist circumference, waist/hip ratio, fasting glucose or insulin levels, baseline free or total plasma cortisol levels, baseline ACTH concentrations, or the plasma cortisol response to CRH. However, CRH-stimulated plasma ACTH concentrations, measured in a polyclonal radio-immunoassay, were significantly greater in prepubertal and early pubertal black girls than in white girls at all time points between 15 and 90 minutes after administration of CRH (area under curve (AUC 1754 +/- 121 pmol/L/min in black girls vs 1304 +/- 124 pmol/L/min in white girls, p < 0.001). This difference was confirmed by an immunoradiometric assay believed to be specific for intact ACTH (AUC 1634 +/- 139 pmol/L/min in black girls vs 1224 +/- 104 pmol/L/min in white girls, p < 0.001). Neither ACTH AUC nor cortisol AUC was significantly correlated with body mass index in either black or white girls. We conclude that there are differences in the hypothalamic-pituitary-adrenal axis of prepubertal and early pubertal black and white girls similar to those found previously in adult women. The cause of these differences remains to be elucidated.