Ketoconazole-tacrolimus coadministration in kidney transplant recipients: two-year results of a prospective randomized study

Effect of Transplanted Bone Marrow on Spleen of Irradiated Pregnant Rats and Their Fetuses

<b>Background and Objective:</b> Prenatal ionizing radiation exposure may hinder fetal and embryonic growth depending on the dose and gestational age. The current study's objective was to discover how bone marrow transplants affected the spleens of pregnant rats that had been subjected to γ (Gamma) radiation. <b>Materials and Methods:</b> Sixty rats that were pregnant were separated into five different groups, each with 6 females. The pregnant rats in the second Group were exposed to 2Gy of γ-rays. Group III; pregnant rats subjected to 2Gy of γ-rays, followed by an intraperitoneal injection of newly prepared bone marrow transplantation (BMT). The fifth Group were exposed to 2Gy γ-rays and received 1 dosage of BMT an hour later. Spleen samples from the pregnant rats as well as their fetuses were taken for histological and histochemical analyses. <b>Results:</b> Gamma rays damaged the splenic tissue of women and their fetuses on days 7 or 14 of pregnancy in a variety of histological and histochemical ways, although bone marrow transplantation significantly reduced the damage. Treated mothers with bone marrow post-radiation showed a noticeable recovery in spleen of their fetuses. Improved spleen architecture was accompanied by appearance of normal content of collagen, polysaccharides and total protein in the fetal spleen tissue especially on day 7 of gestation. <b>Conclusion:</b> Bone marrow transplantation can lessen the damage caused by gamma radiation.

Posttransplantation tuberculosis management in terms of immunosuppressant cost: a case report in Myanmar

Drug interactions between anti-tuberculosis and immunosuppressive medications after renal transplantation are a common problem in Myanmar. The efficacy of both types of drugs can be reduced during the treatment period, which can lead to graft failure and flare-ups of infection. Drug adjustments, with frequent monitoring and close follow-up, are crucial in this period. Ketoconazole decreases tacrolimus metabolism by inhibiting cytochrome P450-3A5 enzymes and P-glycoprotein. It is cost effective and has been frequently used to reduce the dose and cost of tacrolimus. Here, we report the case of a 56-year-old male renal transplant recipient with anti-tuberculosis medications.

Drug Interactions between Antimicrobial and Immunosuppressive Agents in Solid Organ Transplant Recipients

The number of allogeneic solid organ and bone marrow transplants is increasing all over the world. To prevent transplant rejection and treat acute rejection of transplant, immunosuppressant drugs are used. The outcomes of solid organ transplants have dramatically improved over last 30 years, due to availability of multiple immunosuppressive agents, with varied mechanisms of action. The use of intense immunosuppression makes the individual having undergone solid organ transplant at the risk of several serious infections, which may prove fatal. To prevent and treat these infections (when they occur), patients are often given antimicrobial prophylaxis and therapy. The use of antimicrobials can interfere with the metabolism of the immunosuppressants, and may put the patient at risk of developing severe adverse effects due to unwanted increase or decrease in the serum levels of immunosuppressive agents. Knowledge of these interactions is essential for successful management of solid organ transplant patients. We therefore decided to review the literature and present the interactions that commonly occur between these two life-saving groups of drugs.

How to cite this article: Bhagat V, Pandit RA, Ambapurkar S, Sengar M, Kulkarni AP. Drug Interactions between Antimicrobial and Immunosuppressive Agents in Solid Organ Transplant Recipients. Indian J Crit Care Med 2021;25(1):67–76.

Co-administration of Wuzhi tablet (Schisandra sphenanthera extract) alters tacrolimus pharmacokinetics in a dose- and time-dependent manner in rats

ETHNOPHARMACOLOGY RELEVANCE

Tacrolimus is a well-known potent but expensive immunosuppressant. We previously clarified the herb-drug interaction between tacrolimus and Wuzhi tablet (WZ), a prescribed drug of ethanol extract of Schisandra sphenanthera, and showed the ideal effect of WZ on maintaining therapeutic level of tacrolimus and reducing the total drug expense. However, WZ possesses a biphasic effect on regulating CYP3A (the major metabolizing enzyme of tacrolimus), which could induce the mRNA and protein expression after long-term treatment while transiently inhibit the activity of CYP3A. In clinic, clinicians are confused about the relationship between the blood concentration of tacrolimus and the dose and the duration of pretreatment of WZ. Therefore, the effects of the pretreatment time and the dose of WZ on the pharmacokinetics of tacrolimus is urgently needed to be clarified to better combine the use of WZ and tacrolimus in clinic.

AIM OF THE STUDY AND METHOD

This study aimed to investigate the effects of the pretreatment time and the dose of WZ on the pharmacokinetics of tacrolimus in rats.

RESULTS AND CONCLUSIONS

After pretreated rats with WZ for 0, 0.5, 2, 6, 12 or 24 h, the area under the curve (AUC) of tacrolimus was 2.27 ± 0.59, 1.87 ± 1.14, 2.86 ± 0.64, 1.62 ± 0.70, 1.54 ± 1.06 and 1.12 ± 0.69-fold of that of the tacrolimus alone group, respectively. The ratio of AUC of tacrolimus to that of the co-administration group with 0, 62.5, 125, 250, 500 or 750 mg/kg of WZ was 1.00: 1.07: 1.44: 2.60: 2.32: 2.42, respectively. These findings suggested that WZ increased tacrolimus AUC in a pretreatment time- and dose-dependent manner. In line with the in vivo findings, WZ extract inhibited CYP3A activity in a pre-treatment time- and concentration-dependent manner in human liver microsomes. In conclusion, the pharmacokinetics of tacrolimus was significantly affected by the pretreatment time and the dose of WZ. Oral pretreatment with WZ for 0-2 h or co-dosing of 250 mg/kg of WZ most significantly increased the blood concentration of tacrolimus. These findings would be helpful for guiding the reasonable use of WZ and tacrolimus in clinic.

Exploring the safety and efficacy of adding ketoconazole to tacrolimus in pediatric renal transplant immunosuppression

BACKGROUND

Guatemala is a developing country in Central America with limited health resources. In order to expand successful renal transplant care to children and adolescents at the lowest possible cost, our pediatric renal transplant clinic uses a post-transplant tacrolimus-sparing strategy via inhibition of CYP3A4.

AIM

To study the safety, efficacy and the associated cost reduction of ketoconazole in combination with tacrolimus in this pediatric population.

METHODS

A retrospective chart review was carried out among the cohort of pediatric renal transplant recipients treated at the Foundation for pediatric renal patients (Fundación para el Niño Enfermo Renal - FUNDANIER), a pediatric tertiary care renal transplant center in Guatemala City, Guatemala. Patient charts were reviewed to ascertain the number of transplant recipients who were transitioned from tacrolimus based immunosuppression to combination therapy with ketoconazole and tacrolimus. Twenty-five post-transplant patients that used ketoconazole combined with tacrolimus were identified. Anthropometric, clinical and laboratory data was collected from patient charts before and after the transition.

RESULTS

Of the 25 patient charts reviewed 12 (48%) patients were male and the average patient age was 13 years. Twenty-four (96%) transplants were from living donors. There was a non-significant difference between the mean tacrolimus doses six months and two months prior to ketoconazole: -0.10 ± 0.04 (95%CI: 0.007, -0.029), P = 0.23. However, the difference between the mean tacrolimus doses six months prior to ketoconazole initiation and six months after ketoconazole addition was significant: 0.06 ± 0.05 (95%CI: -0.034, -0.086) P < 0.001. All tacrolimus doses were reduced by 45% after the addition of ketoconazole. Therapeutic levels of tacrolimus ranged between 6.8-8.8 ng/mL during the study period and patients demonstrated an increase in estimated glomerular filtration rate. The combination of tacrolimus and ketoconazole resulted in a 21% reduction in cost.

CONCLUSION

Patients experienced an effective dose-reduction of tacrolimus with the administration of ketoconazole. There was no relevant variations in tacrolimus serum levels, number of rejections, or significant liver toxicity. The strategy allowed a cost reduction in pediatric immunosuppressive therapy.

Effects of Wuzhi Capsules on Blood Concentration of Tacrolimus in Renal Transplant Recipients

BACKGROUND Tacrolimus is a widely used immunosuppressant in renal transplant recipients. It was demonstrated in rats and healthy volunteers that Wuzhi capsules could inhibit metabolism and maintain blood concentration of tacrolimus. However, there are no clinical studies of Wuzhi capsules in renal transplant recipients. This research aimed to assess the effect of Wuzhi capsules on the blood concentration of tacrolimus in renal transplant recipients. MATERIAL AND METHODS A total of 158 Chinese renal transplant recipients receiving tacrolimus with or without Wuzhi capsules were included in this retrospective study. The cohort study included 126 recipients, with 86 recipients receiving Wuzhi capsules (WZCs) and the other 40 recipients not receiving WZCs. Another 32 recipients were involved in a self-control study. RESULTS Dose- and body weight-adjusted trough concentrations (C0/D/W) of tacrolimus in the WZC group were found to be significantly higher than that in the non-WZC group (P<0.05). The improvement of C0/D/W by administration of Wuzhi capsules was more significant in CYP3A5 expressers than in non-expressers following subgroup analysis. Furthermore, the WZC group had a remarkably higher proportion of subjects who reached target tacrolimus concentration than in the non-WZC group, both in CYP3A5 expressers (P=0.01) and non-expressers (P<0.001). Multiple linear regression analysis and self-control analysis confirmed the positive impact of Wuzhi capsules on tacrolimus concentration (P<0.001). CONCLUSIONS Wuzhi capsules can increase tacrolimus trough concentration without adverse effects on allograft function, especially in CYP3A5 expressers. Efficient and convenient immunosuppressive effects on renal transplant recipients can be achieved by treatment including administration of Wuzhi capsules.

Efficacy and safety of ketoconazole combined with calmodulin inhibitor in solid organ transplantation: A systematic review and meta-analysis

What is known and objective

Calcineurin inhibitors (CNIs) can significantly improve the results of solid organ transplantation regarding graft and patient survival. However, the high cost, chronic nephrotoxicity and other side effects are major challenges for the long‐term use of these drugs. Ketoconazole can significantly increase the plasma concentration of CNIs by inhibiting the activity of the cytochrome P450 enzyme. The combination of ketoconazole‐CNIs can reduce the cost of medication for patients by reducing the dosage of CNIs, but its safety is still controversial. Therefore, this study was designed to assess the safety and efficacy of this combination.

Methods

We performed a systematic literature search in PubMed, Embase, Cochrane Library and clinicaltrials.gov for randomized controlled trials on ketoconazole and CNI (cyclosporin or tacrolimus) co‐administration in solid organ transplantation. Two authors independently selected studies, assessed the risk of bias and extracted data. The meta‐analysis was performed in RevMan 5.3 provided by the Cochrane Collaboration. PROSPERO registration number: CRD42019118796.

Results and discussion

Five relevant trials with 326 patients were included. Compared with the controls, ketoconazole combined with CNIs can significantly reduce the dose of CNIs in patients receiving solid organ transplantation (WMD = −203.04 mg/day; 95% CI: −310.51 to −95.57, P = .0002). There was no significant difference in serum creatinine between the experimental group and the control group (WMD = −0.19 mg/mL; 95% CI: −0.52 to 0.14, P = .26). In addition, there was no significant difference in the number of rejections between the two groups (OR = 0.58; 95% CI: 0.27 to 1.22, P = .15).

What's new and conclusion

The co‐administration of ketoconazole and CNIs can significantly reduce the dose of CNIs. This combination may be safely used as a CNI‐sparing agent from the time of solid organ transplantation with low‐dose ketoconazole, based on the findings of this review.

Interactions between anti-infective agents and immunosuppressants-Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated guidelines from the Infectious Diseases Community of Practice of the American Society of Transplantation provide an update on potential drug-drug interactions between anti-infectives and immunosuppressants, which are most notable with calcineurin and mTOR inhibitors. Drug-drug interactions may occur through pharmacokinetic mechanisms leading to altered drug concentrations of either the anti-infective or immunosuppressive drug, or by pharmacodynamic interactions increasing or decreasing the efficacy or toxicity of the medications. Many of the significant pharmacokinetic interactions occur through inhibition or induction of the cytochrome 3A4 system by anti-infective agents leading to increased or decreased immunosuppressive agent levels, respectively. The membrane transporter P-glycoprotein is also often involved in drug interactions. Since the last iteration of these guidelines, multiple new hepatitis C virus direct-acting antivirals have become available for use in SOT recipients. Of these agents, some are substrates of cytochrome and drug transporter systems, while others inhibit these systems and may affect immunosuppressive agents. Due to the high risk for drug-drug interactions in the solid organ transplant population, practitioners must be aware of potential interactions and be vigilant in monitoring and adjusting drug dosing when appropriate.

Impact of antiretroviral regimen on renal transplant outcomes in HIV-infected recipients

BACKGROUND

Protease inhibitors (PI) pose a challenge post-transplant due to significant drug interactions with calcineurin inhibitors, prompting many clinicians to convert patients to non-interacting regimens prior to transplant. The purpose of this study was to examine the impact of PI-based regimens on graft outcomes in HIV-infected renal transplant recipients.

METHODS

In this retrospective cohort study, 50 HIV-infected renal allograft recipients (27 receiving a PI regimen, 23 receiving a non-PI regimen) transplanted between 2003-2015 were analyzed.

RESULTS

Cumulative rejection rates at 12 and 36 months were 41% and 54% in the PI group vs 52% and 86% in the non-PI group. At last follow-up, the overall risk of acute rejection in the PI group was 46% lower compared with the non-PI cohort (P = 0.12). Patients who received a PI-based regimen had significantly reduced graft failure rates (P = 0.027). There was no difference between groups in the degree of interstitial fibrosis/tubular atrophy, arteriolar hyalinosis, arterial sclerosis, or glomerular sclerosis on available biopsies, despite longer follow-up time in the PI group.

CONCLUSIONS

Our study suggests that PI-based antiretroviral therapy regimens are associated with improved graft survival and that patients can achieve adequate outcomes on a PI-based regimen when necessary. Due to study limitations, further studies are needed to determine the optimal immunosuppression/antiretroviral therapy regimen post-transplant.

Evaluation of mycophenolate mofetil or tacrolimus in children with steroid sensitive but frequently relapsing or steroid-dependent nephrotic syndrome

AIM

Approximately 30-40% of children with steroid sensitive nephrotic syndrome have frequently relapsing nephrotic syndrome (FRNS) or steroid-dependent nephrotic syndrome (SDNS). Mycophenolate mofetil (MMF) and tacrolimus (TAC) are often alternative treatment choices for these patients.

METHODS

A single-center prospective study was conducted to compare the efficacy of MMF or TAC in reducing relapses and maintaining remission in children with FRNS or SDNS. Of the 72 recruited patients, either MMF (20∼30 mg/kg/d, n = 34) or TAC (0.05∼0.15 mg/kg/d, n = 38) was administered for 12 months.

RESULTS

The mean 6-month relapse rates decreased from 2.56 episodes before therapy to 0.76 episodes in the first 6 months after therapy (c(2) = 44.362, p < 0.001) and 0.67 in the next 6 months (c(2) = 37.817, p < 0.001) in the MMF group. In the TAC group, the mean 6-month relapse rates decreased from 2.39 episodes before therapy to 0.41 episodes in the first 6 months after therapy (c(2) = 62.242, p < 0.001) and 0.42 in next 6 months (c(2) = 67.482, p < 0.001). No significant difference in the relapse rate was found between the groups (before therapy, c(2) = 0.902, p = 0.637; first 6 months, c(2) = 5.358, p = 0.147; second 6 months, c(2) = 4.089, p = 0.252). And there was also no significant difference in cumulative sustained remission and the incidence of adverse events between two groups.

CONCLUSIONS

In combination with low-dose steroids, MMF or TAC presented similar efficacy in maintaining remission in children with FRNS/SDNS in the present study. Therapy with MMF or TAC is a promising strategy with a moderate risk of side effects in children who are steroid sensitive but have FRNS/SDNS.

No Increased Risk of Ketoconazole Toxicity in Drug-Drug Interaction Studies

In July 2013 the U.S. Food and Drug Administration (FDA) released a safety announcement regarding the use of ketoconazole and its adverse drug reactions. The FDA report advised against the use ketoconazole tablets as a first-line treatment for any fungal infections because of the risk of potentially serious drug-drug interactions and liver and adrenal gland complications. The European Medicines Agency (EMA) also proposed to limit the use of oral ketoconazole in fungal infections because of the same risk of harmful effects and interactions. In addition, the FDA also advised against the use of oral ketoconazole in drug interaction studies, in which it has been extensively used as an index inhibitor of drug metabolism. The aim of this investigation was to evaluate the risks of ketoconazole-induced hepatotoxicity described by the FDA and EMA in published drug interaction studies with ketoconazole and compare these data with the toxicity reported for ketoconazole when used as antifungal treatment. In the drug interaction studies (2355 participants; healthy volunteers and patients; median treatment duration, 6 days), only 40 participants were reported to have increased liver transaminase activity (1.7%), and no deaths were reported or associated with ketoconazole. In studies investigating ketoconazole treatment, patients were treated for 276 days (median), and 5.6% of patients had elevated liver enzyme activity. Because of the short treatment period in drug interaction studies the risk of drug-induced hepatic injury is considered very low. As such, we recommend that ketoconazole remain a safe CYP3A index inhibitor for use in drug interaction studies with healthy volunteers.

Combining cytochrome P-450 3A4 modulators and cyclosporine or everolimus in transplantation is successful

AIM: To describe the long term follow-up of kidney allograft recipients receiving ketoconazole with calcineurin inhibitors (CNI) alone or combined with everolimus.

METHODS: This is an open-label, prospective observational clinical trial in low immunologic risk patients who, after signing an Institutional Review Board approved consent form, were included in one of two groups. The first one (n = 59) received everolimus (target blood level, 3-8 ng/mL) and the other (n = 114) azathioprine 2 mg/kg per day or mycophenolate mofetyl (MMF) 2 g/d. Both groups also received tapering steroids, the cytochrome P-450 3A4 (CYP3A4) modulator, ketoconazole 50-100 mg/d, and cyclosporine with C0 targets in the everolimus group of 200-250 ng/mL in 1 mo, 100-125 ng/mL in 2 mo, and 50-65 ng/mL thereafter, and in the azathioprine or MMF group of 250-300 ng/mL in 1 mo, 200-250 ng/mL in 2 mo, 180-200 ng/mL until 3-6 mo, and 100-125 ng/mL thereafter. Clinical visits were performed monthly the first year and quarterly thereafter by treating physicians and all data was extracted by the investigators.

RESULTS: The clinical characteristics of these two cohorts were similar. During the follow up (66 + 31 mo), both groups showed comparable clinical courses, but the biopsy proven acute rejection rate during the full follow-up period seemed to be lower in the everolimus group (20% vs 36%; P = 0.04). The everolimus group did not show a higher surgical complication rate than the other group. By the end of the follow-up period, the everolimus group tended to show a higher glomerular filtration rate. Nevertheless, we found no evidence of a consistent negative slope of the temporal allograft function estimated by the modification of the diet in renal disease formula in any of both groups. At 6 years of follow-up, the uncensored and death-censored graft survivals were 91% and 93%, and 91% and 83% in the everolimus plus cyclosporine, and cyclosporine alone groups, respectively. The addition of ketoconazole saved 80% of cyclosporine and 56% of everolimus doses.

CONCLUSION: Combining CYP3A4 modulators with CNI or mammalian target of rapamycin inhibitor, in low immunological risk kidney transplant recipients is feasible, effective, safe and affordable even in the long term.

Long-term outcome of ketoconazole and tacrolimus co-administration in kidney transplant patients

AIM: To study the long-term outcome of ketoconazole and tacrolimus combination in kidney transplant recipients.

METHODS: From 2006 to 2010, ketoconazole was given in 199 patients and was continued for at least 1 year or until graft failure (Group 1), while 149 patients did not receive any ketoconazole (Group 2). A combination of tacrolimus, mycophenolate and steroid was used as maintenance therapy. High risk patients received basiliximab induction.

RESULTS: Basic demographic data was similar between the 2 groups. The 5-year cumulative incidence of biopsy-confirmed and clinically-treated acute rejection was significantly higher in Group 1 than in Group 2 (34% vs 18%, P = 0.01). The 5-year Kaplan-Meier estimated graft survival (74.3% vs 76.4%, P = 0.58) and patient survival (87.8% vs 87.5%, P = 0.93) were not different between the 2 groups. Multivariable analyses identified ketoconazole usage as an independent risk of acute rejection (HR = 2.33, 95%CI: 1.33-4.07; P = 0.003) while tacrolimus dose in the 2^nd month was protective (HR = 0.89, 95%CI: 0.75-0.96; P = 0.041).

CONCLUSION: Co-administration of ketoconazole and tacrolimus is associated with significantly higher incidence of acute rejection in kidney transplant recipients.

Individualization of tacrolimus dosage basing on cytochrome P450 3A5 polymorphism--a prospective, randomized, controlled study

We investigated how cytochrome P450 (CYP) 3A5 polymorphism affects pharmacokinetics of tacrolimus and its interaction with diltiazem in Chinese kidney transplant recipients. Sixty-two CYP3A5 expressers and 58 non-expressers were, respectively, randomized to receive diltiazem supplement or not. Their pharmacokinetic profiles were acquired on 14th day, sixth month, and 18th month post-transplant and compared among groups. A dosing equation was fit based on above data with CYP3A5 genotype and diltiazem co-administration as variables. Then, necessary initial doses with or without diltiazem were calculated and used in 11 CYP3A5 expressers, respectively, when another 11 expressers received routine doses as control. Trough concentration was measured on the third-day post-transplant and patients failed to reach target range were presented in percentage. These two parameters were compared among three groups. Patients were followed up until June 2010, kidney function, biopsy-proved acute rejection, and other adverse events were monitored. Results showed that CYP3A5 expressers needed more tacrolimus to reach therapeutic concentration window and were more susceptible to diltiazem-induced concentration increase than CYP3A5 non-expressers. CYP3A5 polymorphism-guided dosing equation helped to determine appropriate initial doses of tacrolimus in individuals. In conclusion, CYP3A5 polymorphism profoundly influences pharmacokinetics of tacrolimus and helps to individualize tacrolimus dose.

Treatment of tacrolimus or cyclosporine A in children with idiopathic nephrotic syndrome

BACKGROUND

Cyclosporine A (CsA) and tacrolimus (TAC) are often alternative treatment choices for patients with nephrotic syndrome.

METHODS

In this prospective study, the efficacy and safety of CsA and TAC in inducing and maintaining remission in 74 children with idiopathic nephrotic syndrome (INS) were evaluated.

RESULTS

In terms of short-term efficacy, TAC was more effective than CsA in children with steroid-resistant nephrotic syndrome (χ(2) = 13.75, P = 0.001), although no significant difference in number of episodes of relapse were found in patients with complete remission between the two treatment groups (first year: χ(2) = 0.261, P = 0.88; second year: χ(2) = 2.685, P = 0.26). In patients with frequently relapsing or steroid-dependent nephrotic syndrome, no significant difference in short-term remission (χ(2) = 1.908, P = 0.39) or in relapse frequency during follow-up (within first year: χ(2) = 1.046, P = 0.59; within second year: χ(2) = 0.587, P = 0.75) were found between the two groups. There was a difference in the rate of adverse effects between the two treatment groups [nephrotoxicity: 4/24 (CsA) vs .0/50 (TAC), P = 0.002; hirsutism: 8/24 (CsA) vs. 0/50 (TAC), P < 0.001].

CONCLUSIONS

In our pediatric patient cohort, the treatment of steroid-resistant nephrotic syndrome with tacrolimus was associated with higher efficacy and lower renal toxicity in comparison to CsA, although no favorable outcome in relapse rate during long-term follow-up was seen. On the other hand, tacrolimus was not always the better choice to replace CsA in the treatment of severe frequently relapsing or steroid-dependent nephrotic syndrome.

The genetics of kidney transplantation

Over the last decade, the search for gene variants with the potential to influence transplant outcomes or predispose individuals to host-recipient-related phenotypes has generated a considerable number of studies with conflicting results. Thousands of genotypes have been associated with complex traits related to transplant medicine, including acute rejection, immunosuppressive drug metabolism and side effects, infections, long-term outcomes, and cardiovascular complications. However, these efforts have given disappointing results, both in terms of gaining understanding of the biological basis of disease and in patient management. The methodological weaknesses that constitute the major limitations of most of these studies have been discussed widely. A new generation of approaches is needed to understand the relationship between gene variants and complex kidney transplantation traits. These approaches should be global, to generate original pathophysiological hypotheses, and should rely on advanced genomic tools, including Genome Wide Association studies and Whole Genome Sequencing technologies. Such enterprises will only be successful with the creation of international consortiums that connect partners in clinical, industrial, and academic transplant medicine.

Cost-effective immunosuppressive options for solid organ transplantation: a guide to lower cost for the renal transplant recipient in the USA

Of the numerous risks associated with immunotherapy for the prevention of rejection, cost is perhaps the most universal. In the USA and some other countries, the costs of immunosuppression make transplantation unavailable for some medically viable transplant candidates, and for others who receive a transplant, the long-term costs are economically crippling. Minimization and tapering of immunosuppression, use of generics, manipulation of metabolism, infection surveillance instead of prophylaxis, and advantageous routes of administration are some strategies that can be employed to reduce immunotherapy expense. Using these strategies, we describe an immunosuppression regimen for kidney transplantation that might be only a third of the cost of current 'standard' regimens in the USA. Such a regimen might allow some patients who might not otherwise qualify economically to safely receive a kidney transplant. The purpose of creating an alternative, lower-cost immunotherapy regimen is to give patients a choice. Responsible stewardship of scarce donor organs is the primary, and clearly appropriate, limiting factor.

Deciphering calcineurin inhibitor nephrotoxicity: a pharmacological approach

The calcineurin inhibitors ciclosporin and tacrolimus are used to prevent acute rejection of solid organs after transplantation. Their use can lead to chronic renal damage characterized by progressive and irreversible deterioration of renal function associated with interstitial fibrosis, tubular atrophy, arteriolar hyalinosis and glomerulosclerosis. Many approaches to better understand the mechanisms of this toxicity are in use. The aim of these approaches is to find biomarkers of early kidney injury and potential therapeutic targets. Despite these efforts, the biological processes leading to calcineurin inhibitor nephrotoxicity remain poorly understood. Furthermore, the diagnosis of chronic renal damage remains inaccurate without definitive diagnostic tools, no effective prevention exists and a therapy to treat the damage has yet to be developed. In this article, theories of pharmacodynamics, pharmacokinetics, therapeutic drug monitoring and pharmacogenetics are synthesized in ways that may improve the understanding of mechanisms leading to calcineurin inhibitor toxicity. The importance of global approaches such as toxicogenomics is emphasized to characterize early cellular responses implicated in calcineurin inhibitor nephrotoxicity.

KDIGO clinical practice guideline for the care of kidney transplant recipients

The 2009 Kidney Disease: Improving Global Outcomes (KDIGO) clinical practice guideline on the monitoring, management, and treatment of kidney transplant recipients is intended to assist the practitioner caring for adults and children after kidney transplantation. The guideline development process followed an evidence-based approach, and management recommendations are based on systematic reviews of relevant treatment trials. Critical appraisal of the quality of the evidence and the strength of recommendations followed the Grades of Recommendation Assessment, Development, and Evaluation (GRADE) approach. The guideline makes recommendations for immunosuppression, graft monitoring, as well as prevention and treatment of infection, cardiovascular disease, malignancy, and other complications that are common in kidney transplant recipients, including hematological and bone disorders. Limitations of the evidence, especially on the lack of definitive clinical outcome trials, are discussed and suggestions are provided for future research.

CYP3A5*1/*3 genotype influences the blood concentration of tacrolimus in response to metabolic inhibition by ketoconazole

OBJECTIVES

Ketoconazole retards metabolic degradation of tacrolimus through its effect on the cytochrome P-450 enzyme system and allows reduction in treatment costs. Enzyme activity is determined by a single nucleotide polymorphism (*1/*3) in the CYP3A5 gene.

METHODS

We prospectively investigated the impact of this polymorphism on tacrolimus concentration in a cohort of 79 renal transplant recipients on ketoconazole. Genotyping was carried out by using polymerase chain reaction-restriction fragment length polymorphism technique. Dose-adjusted trough level (C0) was calculated at baseline and at 3, 7, 15, 30, and 60 days.

RESULTS

The baseline C0 was significantly lower in those with at least one *1 allele [44.95+/-14.12 vs. 63.43+/-14.72 (ng/ml)/(mg/kg/day), P<0.0001]. After starting ketoconazole in all genotypes, dose-normalized C0 increased and the cost of therapy decreased. Compared with baseline, the magnitude of increase was 112% and 79% in those without and with *1 allele, respectively (P<0.001). The cost savings were 32% and 39% in mycophenolate mofetil-treated and 47% and 61% in azathioprine-treated patients who were with and without one *1 allele, respectively.

CONCLUSION

We show that the CYP3A5*1/*3 polymorphism is an important determinant of the response to inhibition of tacrolimus metabolism by ketoconazole, with a 30% greater inhibition in those lacking *1 allele. This finding will allow better dose adjustment and minimize exposure to subtherapeutic or toxic concentrations.

Calcineurin inhibitor nephrotoxicity

The use of the calcineurin inhibitors cyclosporine and tacrolimus led to major advances in the field of transplantation, with excellent short-term outcome. However, the chronic nephrotoxicity of these drugs is the Achilles' heel of current immunosuppressive regimens. In this review, the authors summarize the clinical features and histologic appearance of both acute and chronic calcineurin inhibitor nephrotoxicity in renal and nonrenal transplantation, together with the pitfalls in its diagnosis. The authors also review the available literature on the physiologic and molecular mechanisms underlying acute and chronic calcineurin inhibitor nephrotoxicity, and demonstrate that its development is related to both reversible alterations and irreversible damage to all compartments of the kidneys, including glomeruli, arterioles, and tubulo-interstitium. The main question--whether nephrotoxicity is secondary to the actions of cyclosporine and tacrolimus on the calcineurin-NFAT pathway--remains largely unanswered. The authors critically review the current evidence relating systemic blood levels of cyclosporine and tacrolimus to calcineurin inhibitor nephrotoxicity, and summarize the data suggesting that local exposure to cyclosporine or tacrolimus could be more important than systemic exposure. Finally, other local susceptibility factors for calcineurin inhibitor nephrotoxicity are reviewed, including variability in P-glycoprotein and CYP3A4/5 expression or activity, older kidney age, salt depletion, the use of nonsteroidal anti-inflammatory drugs, and genetic polymorphisms in genes like TGF-beta and ACE. Better insight into the mechanisms underlying calcineurin inhibitor nephrotoxicity might pave the way toward more targeted therapy or prevention of calcineurin inhibitor nephrotoxicity.

Differential effects of ketoconazole on exposure to temsirolimus following intravenous infusion of temsirolimus

Intravenous (i.v.) temsirolimus, a novel inhibitor of mammalian target of rapamycin, is approved for the treatment of advanced renal cell carcinoma and is being studied in patients with mantle cell lymphoma. Because temsirolimus and its primary metabolite, sirolimus, are metabolised by the cytochrome P450 3A4 pathway (CYP3A4), the potential exists for pharmacokinetic (PK) drug interactions with the numerous agents that modulate CYP3A4 isozyme activity. We investigated the effects of ketoconazole, a potent CYP3A4 inhibitor, on the PK profile of i.v. temsirolimus in healthy adults. Coadministration of 400 mg oral ketoconazole with 5 mg i.v. temsirolimus had no significant effect on temsirolimus maximum concentration (C_max) or area under the concentration curve (AUC). However, mean AUC increased 3.1-fold and AUC_sum (sum of temsirolimus plus sirolimus AUCs) increased 2.3-fold compared with temsirolimus alone. A single 5-mg dose of temsirolimus with ketoconazole was well tolerated, and there were no unexpected safety results. Therefore, in cancer patients receiving 25 mg i.v. temsirolimus, concomitant treatment with agents that have strong CYP3A4 inhibition potential should be avoided. If a concomitant strong CYP3A4 inhibitor is necessary, a temsirolimus dose reduction to 12.5 mg weekly should be considered.

High-throughput synergy screening identifies microbial metabolites as combination agents for the treatment of fungal infections

The high mortality rate of immunocompromised patients with fungal infections and the limited availability of highly efficacious and safe agents demand the development of new antifungal therapeutics. To rapidly discover such agents, we developed a high-throughput synergy screening (HTSS) strategy for novel microbial natural products. Specifically, a microbial natural product library was screened for hits that synergize the effect of a low dosage of ketoconazole (KTC) that alone shows little detectable fungicidal activity. Through screening of approximately 20,000 microbial extracts, 12 hits were identified with broad-spectrum antifungal activity. Seven of them showed little cytotoxicity against human hepatoma cells. Fractionation of the active extracts revealed beauvericin (BEA) as the most potent component, because it dramatically synergized KTC activity against diverse fungal pathogens by a checkerboard assay. Significantly, in our immunocompromised mouse model, combinations of BEA (0.5 mg/kg) and KTC (0.5 mg/kg) prolonged survival of the host infected with Candida parapsilosis and reduced fungal colony counts in animal organs including kidneys, lungs, and brains. Such an effect was not achieved even with the high dose of 50 mg/kg KTC. These data support synergism between BEA and KTC and thereby a prospective strategy for antifungal therapy.