Azathioprine metabolism: pharmacokinetics of 6-mercaptopurine, 6-thiouric acid and 6-thioguanine nucleotides in renal transplant patients

Nucleoside-based anticancer drugs: Mechanism of action and drug resistance

Nucleoside-based drugs, recognized as purine or pyrimidine analogs, have been potent therapeutic agents since their introduction in 1950, deployed widely in the treatment of diverse diseases such as cancers, myelodysplastic syndromes, multiple sclerosis, and viral infections. These antimetabolites establish complex interactions with cellular molecular constituents, primarily via activation of phosphorylation cascades leading to consequential interactions with nucleic acids. However, the therapeutic efficacy of these agents is frequently compromised by the development of drug resistance, a continually emerging challenge in their clinical application. This comprehensive review explores the mechanisms of resistance to nucleoside-based drugs, encompassing a wide spectrum of phenomena from alterations in membrane transporters and activating kinases to changes in drug elimination strategies and DNA damage repair mechanisms. The critical analysis in this review underlines complex interactions of drug and cell and also guides towards novel therapeutic strategies to counteract resistance. The development of targeted therapies, novel nucleoside analogs, and synergistic drug combinations are promising approaches to restore tumor sensitivity and improve patient outcomes.

Adaptive Immunosuppression in Lung Transplant Recipients Applying Complementary Biomarkers: The Zurich Protocol

Achieving adequate immunosuppression for lung transplant recipients in the first year after lung transplantation is a key challenge. Prophylaxis of allograft rejection must be balanced with the adverse events associated with immunosuppressive drugs, for example infection, renal failure, and diabetes. A triple immunosuppressive combination is standard, including a steroid, a calcineurin inhibitor, and an antiproliferative compound beginning with the highest levels of immunosuppression and a subsequent tapering of the dose, usually guided by therapeutic drug monitoring and considering clinical results, bronchoscopy sampling results, and additional biomarkers such as serum viral replication or donor-specific antibodies. Balancing the net immunosuppression level required to prevent rejection without overly increasing the risk of infection and other complications during the tapering phase is not well standardized and requires repeated assessments for dose-adjustments. In our adaptive immunosuppression approach, we additionally consider results from the white blood cell counts, in particular lymphocytes and eosinophils, as biomarkers for monitoring the level of immunosuppression and additionally use them as therapeutic targets to fine-tune the immunosuppressive strategy over time. The concept and its rationale are outlined, and areas of future research mentioned.

On-demand reconstitutable hyaluronic acid-doped azathioprine microcrystals effectively ameliorate ulcerative colitis via selective accumulation in inflamed tissues

Although CD44-targeted delivery of pure drug microcrystals of azathioprine (AZA) could be a desirable approach to treat ulcerative colitis (UC), premature drug release and systemic absorption before reaching the colitis region remain a major obstacle. In this study, to overcome these limitations, we developed on-demand reconstitutable HA-doped AZA microcrystals (EFS/HA-AZAs) via incorporating hyaluronic acid (HA)-doped AZA microcrystals (HA-AZAs) into a Eudragit FS (EFS) microcomposite. Since EFS acts as a protective layer, the premature release of AZA in the simulated conditions of the stomach and small intestine was substantially reduced, while HA-AZAs were successfully reconstituted from the EFS/HA-AZAs in the colonic environment, resulting from the pH-triggered dissolution of EFS. After complete reconstitution of HA-AZAs in the colon, HA-AZAs selectively accumulated in the inflamed region via the HA-CD44 interaction. Owing to successful colitis-targeted delivery, EFS/HA-AZAs showed potent anti-inflammatory effects in a dextran sulfate sodium-induced murine colitis model within 7 days without systemic toxicity. These results suggest that EFS/HA-AZAs could be a promising drug delivery system for UC treatment.

Second-line and third-line therapy for autoimmune hepatitis: A position statement from the European Reference Network on Hepatological Diseases and the International Autoimmune Hepatitis Group

Most patients with autoimmune hepatitis respond well to standard immunosuppressive therapy with steroids and azathioprine, and while untreated disease is usually fatal, patients who respond well to therapy have an excellent prognosis. However, insufficient response to standard therapy or intolerable side effects requiring dose adaptions or treatment changes occur in 10-20% of patients. While there is fairly good agreement on second-line treatment options, there is very wide variation in the indication and use of possible third-line therapies. Herein, the European Reference Network on Hepatological Diseases (ERN RARE-LIVER) and the International Autoimmune Hepatitis Group (IAIHG) outline a treatment algorithm for both children and adults that should help to standardise treatment approaches, in order to improve patient care and to enable the comparison of treatment results between scientific publications.

Systemic immunosuppressive therapies for uveitis in developing countries

There are multiple approaches to inhibit inflammatory molecules and pathways in noninfectious uveitis. The cornerstone of local and systemic anti-inflammatory treatment is corticosteroid therapy. Corticosteroids remain the most potent and efficacious drugs for treating intraocular inflammation. However, their long-term use is limited by their medium- and long-term side effects, which are a major concern. The approach taken to limit corticosteroid side effects is to introduce steroid-sparing agents that suppress the inflammatory pathways and immune response differently than corticosteroids. There are several classes of such drugs that are affordable, effective, and generally well-tolerated. Relatively recently, an increasing range of biologic agents has become available to treat intraocular inflammation. However, the relatively expensive cost of these therapies limits their use in the developing world. This systemic review aimst to discuss the use of corticosteroids and different immunosuppressive regimens in the management of various uveitides.

The Influence of Preoperative Medications on Postoperative Complications in Patients After Intestinal Surgery for Crohn's Disease

BACKGROUND

Many patients with Crohn's disease (CD) are treated with medications, including steroids, immunomodulators, and anti-tumor necrosis factor alpha (anti-TNF-α) agents, at the time of surgery. This study evaluated the effects of these medications on postoperative complications in CD patients.

METHODS

This retrospective study analyzed patients who underwent bowel resection for CD between January 2006 and December 2015. Postoperative complications were defined as a Clavien-Dindo classification of grade 2A or higher within the first 30 days after surgery.

RESULTS

Of the 817 patients enrolled, 687 patients received bowel resection and anastomosis without stoma formation. Of 687 patients, 381 (55.5%) were being treated with preoperative medications at the time of surgery (medication group) and 306 (44.5%) were not (nonmedication group). The overall rate of postoperative complications was not different between the medication and nonmedication groups (23.4% vs 21.9%, P = 0.36). Preoperative treatments with immunomodulators plus anti-TNF-α agents (relative risk [RR], 2.314; 95% confidence interval [CI], 1.126-4.753; P = 0.022) and treatment with immunomodulators plus steroids (RR, 2.536; 95% CI, 1.124-5.725; P = 0.025) were risk factors for infectious complications. Preoperative treatments with immunomodulators plus anti-TNF-α agents (RR, 2.731; 95% CI, 1.102-6.769; P = 0.03) and treatment with immunomodulators plus steroids (RR, 3.118; 95% CI, 1.169-8.320; P = 0.023) were significantly associated with increased risk of intra-abdominal sepsis.

CONCLUSIONS

Preoperative treatments with immunomodulators plus anti-TNF-α agents or steroids were risk factors for infectious complications, especially intra-abdominal sepsis in patients who underwent bowel resection and anastomosis.

Lower 6-MMP/6-TG Ratio May Be a Therapeutic Target in Pediatric Autoimmune Hepatitis

BACKGROUND

Azathioprine (AZA) is the mainstay of maintenance therapy in pediatric autoimmune hepatitis (AIH). The use of thiopurines metabolites to individualize therapy and avoid toxicity has not, however, been clearly defined.

METHODS

Retrospective analysis of children ≤18 years diagnosed with AIH between January 2001 and 2016. Standard definitions were used for treatment response and disease flare. Thiopurine metabolite levels were correlated with the corresponding liver function test.

RESULTS

A total of 56 children (32 girls) were diagnosed with AIH at a median age of 11 years (interquartile range [IQR] 9). No difference in 6-thioguanine-nucleotide (6-TG) levels (271[IQR 251] pmol/8 × 10 red blood cell vs 224 [IQR 147] pmol/8 × 10 red blood cell, P = 0.06) was observed in children in remission when compared with those who were not in remission. No correlation was observed between the 6-TG and alanine aminotransferase levels (r = -0.179, P = 0.109) or between 6-methyl-mercaptopurine (6-MMP) and alanine aminotransferase levels (r = 0.139, P = 0.213). The 6-MMP/6-TG ratio was significantly lower in patients who were in remission (2[7] vs 5 (10), P = 0.04). Using a quartile analysis, we found that having a ratio of <4 was significantly associated with being in remission with OR 2.50 (95% confidence interval 1.02-6.10), P = 0.047. Use of allopurinol with low-dose AZA in 6 children with preferential 6-MMP production brought about remission in 5/6 (83.3%).

CONCLUSIONS

Thiopurine metabolite levels should be measured in patients with AIH who have experienced a loss of remission. A 6-MMP/6-TG ratio of <4 with the addition of allopurinol could be considered in these patients.

Azathioprine-induced pancytopenia with normal TPMT activity presenting with HSV oral ulcers

A 65-year-old man with treatment-resistant psoriatic arthritis, hypertension, dyslipidaemia and benign prostatic hyperplasia (BPH) presented with herpes simplex virus (HSV) oral ulcers and a recent 15 lb weight loss due to reduced consumption. Five weeks previously, his methotrexate was tapered and he had begun taking azathioprine. The patient's thiopurine S-methyltransferase (TPMT) activity level was normal prior to starting azathioprine. He was found to have pancytopenia with normal folate levels and azathioprine was discontinued. His pancytopenia worsened, with a nadir 8 days after stopping azathioprine, before returning to normal levels. His oral ulcers improved and he was able to tolerate solid food. This case illustrates that decreased TPMT activity is not the only risk factor for pancytopenia as an adverse reaction to azathioprine. Furthermore, HSV stomatitis may be the presenting symptom of pancytopenia. The timeline of improvement in cell counts illustrated in this patient has implications for the management of suspected azathioprine-induced pancytopenia.

Mechanisms of action of mycophenolate mofetil

Mycophenolate mofetil (MMF, CellCept®) is a prodrug of mycophenolic acid (MPA), an inhibitor of inosine-5′‘monophosphate dehydrogenase. MPA depletes guanosine nucleotides preferentially in T and B lymphocytes and inhibits their proliferation, thereby suppressing cell-mediated immune responses and antibody formation. MPA also inhibits the glycosylation and expression of adhesion molecules, and the recruitment of lymphocytes and monocytes into sites of inflammation. MPA depletes tetrahydrobiopterin and decreases the production of nitric oxide by inducible NO synthase without affecting the activity of constitutive NO synthases. Activated macrophages produce NO and superoxide, which combine to generate tissue-damaging peroxynitrite. By these two mechanisms MMF exerts anti-inflammatory activity. Unlike calcineurin inhibitors, MMF is not nephrotoxic and does not induce the production of TGF β, which is fibrogenic. MMF does not increase blood pressure, cholesterol levels or triglyceride levels in recipients. MMF reduces acute and chronic rejection in allograft recipients and is efficacious in some nephropathies. Evidence is accumulating that MMF may have clinical utility in some autoimmune disorders.

Immunosuppression for in vivo research: state-of-the-art protocols and experimental approaches

Almost every experimental treatment strategy using non-autologous cell, tissue or organ transplantation is tested in small and large animal models before clinical translation. Because these strategies require immunosuppression in most cases, immunosuppressive protocols are a key element in transplantation experiments. However, standard immunosuppressive protocols are often applied without detailed knowledge regarding their efficacy within the particular experimental setting and in the chosen model species. Optimization of such protocols is pertinent to the translation of experimental results to human patients and thus warrants further investigation. This review summarizes current knowledge regarding immunosuppressive drug classes as well as their dosages and application regimens with consideration of species-specific drug metabolization and side effects. It also summarizes contemporary knowledge of novel immunomodulatory strategies, such as the use of mesenchymal stem cells or antibodies. Thus, this review is intended to serve as a state-of-the-art compendium for researchers to refine applied experimental immunosuppression and immunomodulation strategies to enhance the predictive value of preclinical transplantation studies.

Preoperative Use of Methotrexate and the Risk of Early Postoperative Complications in Patients with Inflammatory Bowel Disease

BACKGROUND

Preoperative immunosuppressive use among patients with Crohn's disease or ulcerative colitis may lead to an increased risk of postoperative complications. There is limited information on the preoperative safety profile of methotrexate (MTX) in inflammatory bowel disease (IBD).

METHODS

A retrospective study of patients who underwent abdominal surgery for IBD between 1993 and 2012 was performed and records abstracted, including preoperative use of MTX, azathioprine/6-mercaptopurine, antitumor necrosis factor, and corticosteroids. Early postoperative complications, including death, septic, and nonseptic complications were identified. A meta-analysis was also performed on the use of preoperative MTX in patients with IBD or rheumatoid arthritis.

RESULTS

A total of 180 patients with IBD underwent abdominal surgery. A total of 15 patients received MTX either monotherapy or in combination therapy. Total early postoperative complications were identified in 71 (39%) patients, specifically 5 patients on oral MTX. A total of 51 cases (28%) of septic complications and 20 (11%) nonseptic. No significant association between the use of MTX and early postoperative complications was found. The odds ratio (OR) of complications versus no complications associated with MTX was 0.75 (95% CI, 0.25-2.29) and with azathioprine/6-mercaptopurine, OR 1.48 (95% CI, 0.77-2.84). The odds of a septic complication associated with MTX were 0.58 (95% CI, 0.09-3.73), and higher in azathioprine/6-mercaptopurine, OR 3.97 (95% CI, 1.03-15.3). Our meta-analysis also did not reveal an increased risk of postoperative complications in IBD or rheumatoid arthritis on preoperative MTX (OR 0.62, 95% CI, 0.34-1.15).

CONCLUSIONS

Preoperative MTX use does not seem to be associated with early postoperative complications in IBD.

Role of exclusive enteral nutrition in the preoperative optimization of patients with Crohn's disease following immunosuppressive therapy

We conducted a study to evaluate the impact of the exclusive enteral nutrition (EEN) on perioperative outcome in Crohn's disease (CD) patients following immunosuppressive therapy. Patients with CD followed at a referral center between January 2001 and March 2014 who underwent abdominal surgery were identified. Patients were divided into 4 groups: patients not exposed to immunosuppressive agents in the previous 8 weeks before surgery (group 1); patients received immunosuppressive medications without preoperative drug-free interval (group 2); patients had preoperative immunosuppressants-free interval (group 3); patients treated with adding EEN to preoperative immunosuppressants-free interval regimen (group 4). Urgent operation requirement, stoma creation, postoperative complications, readmission, and reoperation were compared in patients among groups. Overall, 708 abdominal surgeries performed in 498 CD patients were identified. Three hundred seventy-six (53.11%) surgeries performed in those receiving preoperative immunosuppressive medications. Compared with other groups, group 2 had increased postoperative complications, more frequent urgent operation, and higher rate of stoma creation. Patients in group 4 were found to have better outcome including lower rate of stoma creation (P < 0.05), and decreased incidence of postoperative complications (P < 0.05) compared with group 2 and group 3. Additionally, decreased urgent operation requirement (P < 0.05) and extended preoperative drug-free interval (P < 0.001) were observed in the group 4 than those in the group 3. Preoperative optimization of CD following immunosuppressive therapy by EEN prolongs the immunosuppressants-free interval, reduces the risk of urgent surgery and reoperation, and most importantly, decreases complications after abdominal surgery.

Genes and beans: pharmacogenomics of renal transplant

Advances in the management of patients after solid organ transplantation have led to dramatic decreases in rates of acute rejection, but long-term graft and patient survival have remained unchanged. Individualized therapy after transplant will ideally provide adequate immunosuppression while limiting the adverse effects of drug therapy that significantly impact graft survival. Therapeutic drug monitoring represents the best approximation of individualized drug therapy in transplant at this time; however, obtaining pharmacogenomic data in transplant patients has the potential to enhance our current practice. Polymorphisms of target genes that impact pharmacokinetics have been identified for most immunosuppressants, including tacrolimus, cyclosporine, mycophenolate, azathioprine and sirolimus. In the future, pre-emptive assessment of a patient's genetic profile may inform drug selection and provide information on specific doses that will improve efficacy and limit toxicity.

Review article: the management of autoimmune hepatitis beyond consensus guidelines

BACKGROUND

Consensus guidelines aid in the diagnosis and management of autoimmune hepatitis, but they are frequently based on low-quality clinical evidence, conflicting experiences and divergent opinions. Recommendations may be weak, discrepant or non-existent at critical decision points.

AIMS

To identify the decision points where guidelines are weak or non-existent and review the evidence essential in the decision process.

METHODS

Full-text articles published in English using the keyword 'autoimmune hepatitis' were identified by PubMed from 1972 to 2013. Personal experience and investigations in autoimmune hepatitis also identified important contributions.

RESULTS

Seventy per cent of the guidelines developed by the American Association for the Study of Liver Diseases and 48% of those proposed by the British Society of Gastroenterology are based on low-quality evidence, conflicting experiences or divergent opinions. The key uncertainties in diagnosis relate to the timing of liver biopsy, recognising acute severe (fulminant) disease, interpreting coincidental nonclassical histological changes, accommodating atypical or deficient features in non-White patients, differentiating drug-induced from classical disease and identifying overlap syndromes. The key uncertainties in management relate to pre-treatment testing for thiopurine methyltransferase activity, treating asymptomatic mild disease, determining treatment end points, managing suboptimal responses, incorporating nonstandard medications as front-line and salvage agents, using azathioprine in pregnancy and instituting surveillance for hepatocellular carcinoma.

CONCLUSIONS

Consensus guidelines are fraught with uncertainties in the diagnosis and management of autoimmune hepatitis. Each decision point must counterbalance the current available evidence and tailor the application of this evidence to the individual patient.

Drug choices in autoimmune hepatitis: part B--Nonsteroids

Nonsteroidal medications, previously unfamiliar in the management of autoimmune hepatitis, can supplement or replace conventional corticosteroid regimens, especially in problematic patients. Mycophenolate mofetil is a next-generation purine antagonist that has been useful in treating patients with azathioprine intolerance. It has been less effective in salvaging patients with steroid-refractory disease. Azathioprine is the choice as a corticosteroid-sparing agent in treatment-naive patients and in individuals with corticosteroid intolerance, incomplete response and relapse after drug withdrawal. Tacrolimus is preferred over cyclosporine for recalcitrant disease because of its established preference in organ transplantation, but replacement with cyclosporine should be considered if the disease worsens on treatment. Rapamycin has antiproliferative and proapoptotic actions that warrant further study in autoimmune hepatitis. The nonstandard, nonsteroidal medications are mainly salvage therapies with off-label indications that must be used in highly individualized and well-monitored clinical situations.

Autoantibody-negative autoimmune hepatitis

Autoimmune hepatitis has a variable clinical phenotype, and the absence of conventional autoantibodies does not preclude its diagnosis or need for treatment. The goals of this review are to describe the frequency and nature of autoantibody-negative autoimmune hepatitis, indicate its outcome after corticosteroid treatment, and increase awareness of the diagnosis in patients with unexplained acute and chronic hepatitis. The frequency of presumed autoantibody-negative autoimmune hepatitis in patients with acute and acute severe presentations is ≤7%, and its frequency in patients with chronic presentations is 1-34%. Patients with acute presentations can have normal serum γ-globulin levels, centrilobular zone 3 necrosis, and low pre-treatment international diagnostic scores. Liver tissue examination is essential for the diagnosis, and hepatic steatosis can be a co-morbid feature. The comprehensive international scoring system can support but never override the clinical diagnosis pre-treatment, and non-standard serological markers should be sought if the clinical diagnosis is uncertain or the diagnostic score is low. A 3-month treatment trial with corticosteroids should be considered in all patients, regardless of the serological findings, and improvements have occurred in 67-87% of cases. Autoantibody-negative autoimmune hepatitis may be associated with an autoantibody outside the conventional battery; it may have a signature autoantibody that is still undiscovered, or its characteristic autoantibodies may have been suppressed or have a delayed expression. The pathogenic mechanisms are presumed to be identical to those of classical disease. Autoantibody-negative autoimmune hepatitis is an infrequent but treatable disease that must be considered in unexplained acute and chronic hepatitis.

6-Mercaptopurine transport in human lymphocytes: correlation with drug-induced cytotoxicity

OBJECTIVE

  6-mercaptopurine (6-MP) is efficacious in the treatment of inflammatory bowel disease (IBD). However, about one-third of patients respond poorly to therapy. This study aimed to characterize the inherent differences in 6-MP transport that may cotribute to the differences in treatment responses.

METHODS

  Intracellular 6-MP accumulation was assayed in Epstein-Barr virus (EBV)-transformed lymphocytes from IBD patients, using (14) C-radiolabeled 6-MP. Cell proliferation was determined by methyl thiazolyl tetrazolium (MTT) assay. Apoptosis was assayed based on the activation of caspase 3. The expressions of 15 potential 6-MP transporters were evaluated by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

  Intracellular 6-MP accumulation, varying significantly among patients, was carrier-dependent and partially sodium-dependent. 6-MP cytotoxicity was, at least in part, due to apoptosis and correlated with intracellular drug accumulation. The efflux transporters did not appear to contribute to the variability of intracellular drug accumulation between patients, since none correlated with drug accumulation or cytotoxicity. Rather, differential expression of five influx/uptake transporters might be a key contributor to the difference in the accumulation of and susceptibility to the drug.

CONCLUSIONS

  The heterogeneity of the drug transporters may be the reason for the therapeutic sensitivity of 6-MP in IBD patients. As the 6-MP uptake is a carrier-mediated and partially sodium-dependent process, future studies are necessary to evaluate the role of the putative transporters and their correlation with drug sensitivity in patients.

Review article: the benefits of pharmacogenetics for improving thiopurine therapy in inflammatory bowel disease

BACKGROUND

Thiopurines represent an effective and widely prescribed therapy in inflammatory bowel disease (IBD). Concerns about toxicity, mainly resulting from a wide inter-individual variability in thiopurine metabolism, restrict their use. Optimal thiopurine dosing is challenging for preventing adverse drug reactions and improving clinical response.

AIM

To review efficacy and toxicity of thiopurines in IBD. To provide pharmacogenetic-based therapeutic recommendations.

METHODS

We conducted a query on PubMed database using 'inflammatory bowel disease', 'thiopurine', 'azathioprine', '6-mercaptopurine', 'TPMT', 'pharmacogenetics', 'TDM', and selected relevant articles, especially clinical studies.

RESULTS

Thiopurine metabolism - key enzyme: thiopurine S-methyltransferase (TPMT) - modulates clinical response, as it results in production of the pharmacologically active and toxic metabolites, the thioguanine nucleotides (6-TGN). Adjusting dosage according to TPMT status and/or metabolite blood levels is recommended for optimising thiopurine therapy (e.g. improving response rate up to 30% or decreasing haematological adverse events of 25%). Other enzymes or transporters of interest, as inosine triphosphatase (ITPase), glutathione S-transferase (GST), xanthine oxidase (XO), aldehyde oxidase (AOX), methylene tetrahydrofolate reductase (MTHFR) and ATP-binding cassette sub-family C member 4 (ABCC4) are reviewed and discussed for clinical relevance.

CONCLUSIONS

Based on the literature data, we provide a therapeutic algorithm for thiopurines therapy with starting dose recommendations depending on TPMT status and thereafter dose adjustments according to five metabolite profiles identified with therapeutic drug monitoring (TDM). This algorithm allows a dosage individualisation to optimise the management of patients under thiopurine. Furthermore, identification of new pharmacogenetic biomarkers is promising for ensuring maximal therapeutic response to thiopurines with a minimisation of the risk for adverse events.

Azathioprine-related myelosuppression in a patient homozygous for TPMT*3A

BACKGROUND

A 50-year-old man who had received a simultaneous pancreas and kidney transplant 9 years earlier developed pancytopenia 3 weeks after starting azathioprine therapy to treat worsening proteinuria suspected to be caused by sirolimus.

INVESTIGATIONS

Laboratory tests, including complete blood counts, measurement of serum levels of vitamin B(12) and folate, liver function tests, virological assays, and thiopurine S-methyltransferase (TPMT) genotyping.

DIAGNOSIS

Severe myelosuppression as a consequence of azathioprine therapy in a patient homozygous for the TPMT*3A allele.

MANAGEMENT

Discontinuation of azathioprine, treatment with an erythropoiesis-stimulating agent, red blood cell transfusions, filgrastim (a granulocyte colony-stimulating factor analogue) and folic acid.

Emerging opportunities for site-specific molecular and cellular interventions in autoimmune hepatitis

Current corticosteroid-based treatments of autoimmune hepatitis frequently have incomplete or unsatisfactory outcomes, side effects, and excessive immune suppression. The goal of this review is to describe the advances in developing animal models of autoimmune hepatitis and in treating diverse immune-mediated diseases that make pursuit of site-specific molecular and cellular inventions in autoimmune hepatitis feasible. Prime source and review articles in English were selected by a Medline search through October 2009. A murine model infected with an adenovirus expressing human CYP2D6 is a resource for evaluating new therapies because of its histological and serological features, persistence, and progressive hepatic fibrosis. Synthetic analog peptides that block autoantigen expression, a dimeric recombinant human fusion protein of cytotoxic T lymphocyte antigen-4, monoclonal antibodies against tumor necrosis factor-alpha, recombinant interleukin 10, tolerization techniques for disease-triggering autoantigens, T regulatory cell transfer, vaccination against antigen-specific cytotoxic CD8+ T cells, and gene silencing methods using small inhibitory RNAs are feasible interventions to explore. Treatments directed at dampening immunocyte activation with soluble cytotoxic T lymphocyte antigen-4, inhibiting immunocyte differentiation with recombinant interleukin 10, and improving immunosuppressive activity with regulatory T cell modulation have the most immediate promise. Progress in the development of an animal model of autoimmune hepatitis and experiences in other immune-mediated diseases justify the evaluation of site-specific molecular and cellular interventions in this disease.

Modulating dendritic cells (DC) from immunogenic to tolerogenic responses: a novel mechanism of AZA/6-MP

Azathioprine (Aza), 6-Mercaptopurine (6-MP) and 6-Thioguanine (6-TG) are thiopurine drugs widely used as immunosuppressants/anti-inflammatory agents in organ transplantation and chemotherapy. Aza is well tolerated and effective in modifying the course of MS. Here we investigated the action of 6-MP on human dendritic cells (DCs). We described for the first time that 6-MP impairs in vitro differentiation of DCs, has an inhibitory effect during DC activation processes inducing a functionally less immunogenic phenotype. Moreover, 6-MP significantly reduces DC IL-23 production and CCR7 expression, at the same time induces IL-10 augmentation. All these findings add a novel action mechanism in Aza immune modulation.

Effects of interactions of antibacterial drugs with each other and with 6-mercaptopurine on in vitro growth of Mycobacterium avium subspecies paratuberculosis

OBJECTIVES

Mycobacterium avium subspecies paratuberculosis (MAP) has been targeted for treatment with clarithromycin and rifamycin derivatives in numerous cases of Crohn's disease (CD). 6-Mercaptopurine and its pro-drug azathioprine are widely used as immunomodulators in the treatment of CD and have recently been shown to have anti-MAP activity in vitro. The objectives of the study were to evaluate the in vitro effects on MAP of (i) 6-mercaptopurine when combined with each of eight conventional antibacterial agents with in vitro anti-MAP activity and (ii) antibacterial combinations consisting of two drugs (clarithromycin combined with amikacin, rifampicin, ciprofloxacin or ethambutol) and three drugs (clarithromycin, rifabutin and clofazimine).

METHODS

The drug interaction effects on nine human isolates of MAP were determined by the chequerboard method adapted for the BACTECMGIT960 culture system and by calculation of the fractional inhibitory concentration index (FICI) for drug combinations.

RESULTS

Synergism (FICI < or = 0.5) was observed between 6-mercaptopurine and azithromycin (seven isolates), clarithromycin, rifampicin, rifabutin (four isolates each) and ethambutol (two isolates). 6-Mercaptopurine was not antagonistic with any of the antibacterial agents tested. Among the combinations of two and three antibacterials tested, the clarithromycin/rifampicin combination was synergistic against four isolates, while all other combinations showed no interaction.

CONCLUSIONS

This in vitro study suggests that 6-mercaptopurine may be synergistic with macrolides and rifamycin derivatives against MAP. The activity of clarithromycin against MAP seems to be enhanced by rifampicin.

Current and future treatments of autoimmune hepatitis

Corticosteroid therapy induces clinical, laboratory and histological improvements in 80% of patients with autoimmune hepatitis. Prednisone, alone or at a lower dose in combination with azathioprine, increases the 20-year life expectancy to 80% and prevents or reduces hepatic fibrosis in 79% of patients. The combination regimen is preferred and treatment should be considered in all patients with active disease. The duration of therapy is finite and the medication should be discontinued after resolution of all manifestations of inflammatory activity, including the histological changes. Relapse after drug withdrawal occurs in 50-79% of patients, and it should be treated with long-term azathioprine (2 mg/kg daily). Salvage therapies for individuals intolerant of or refractory to the conventional regimens include high-dose corticosteroids, with or without high-dose azathioprine, 6-mercaptopurine, mycophenolate mofetil, tacrolimus or ciclosporin. Liver transplantation should be considered in patients with hepatic failure unresponsive to corticosteroid treatment, decompensated cirrhosis with a Model for End-Stage Liver Disease score of at least 15 points, or hepatocellular carcinoma that meets transplantation criteria. Autoimmune hepatitis recurs after transplantation in at least 17% of patients, and it typically improves after adjustments in the immunosuppressive regimen. Future therapies are likely to include mesenchymal stem cell transplantation, adoptive transfer of T regulatory cells, and cytokine manipulation. The emergence of new treatments will require the development of a collaborative network of clinical and basic investigators, as the complexity and specificity of current management problems require solutions that exceed the capabilities of single institutions.

Follow-up of pregnant women with autoimmune hepatitis: the disease behavior along with maternal and fetal outcomes

GOALS

To assess maternal and fetal outcomes and clinical management of pregnancy in patients with autoimmune hepatitis (AIH).

BACKGROUND

There is a paucity of information about maternal and fetal outcomes, and AIH activity during pregnancy and in the postpartum period. There is no consensus about the administration of azathioprine during pregnancy and breastfeeding.

STUDY

Retrospective analysis of 54 pregnancies (3 still in progress) in 39 AIH patients.

RESULTS

The median age at conception was 24 years, and 68.4% of women had liver cirrhosis. Before conception and in early pregnancy, azathioprine and prednisone were administered in 48.1%, but treatment regimen was usually changed further to 20 mg/d prednisone; and 20.4% were off treatment. There were 36 livebirths, and fetal loss rates were 29.4% (13 miscarriages, 1 stillbirth, and 1 ectopic pregnancy). Preterm birth rate was 11.8%. In 2 cases, there was acute fetal distress; and in 2 others congenital malformations (3.9%). The rate of serious maternal complication was 7.8%, with no deaths. There were no flares in 41.2% pregnancies, but aminotransferase elevations occurred in 54.9%, 31.4% of which were true AIH relapses, only registered in the postpartum period.

CONCLUSIONS

Despite the high fetal miscarriage rate, pregnancy in AIH was safe. Patients needed careful monitoring, especially in the postpartum period because of relapses. There was no evidence of a cause and effect relationship among azathioprine administration and premature births and congenital abnormalities, but more studies are necessary. Higher doses of prednisone may be an alternative option for those who prefer azathioprine withdrawal during pregnancy.

Severe Cholestatic Hepatitis Caused by Azathioprine

A male patient receiving azathioprine treatment for discoid lupus erythematodes developed severe cholestatic hepatitis between 14 and 21 days after initiation of the treatment with peak bilirubin levels of 62.4 mg/dL. Other causes of hepatic dysfunction including viral hepatitis were clinically and serologically excluded. Liver biopsy revealed cholestatic hepatocellular damage. At 14 days after discontinuation of azathioprine the liver function (transaminases and bilirubin) began to improve. Only alcaline phosphatase and gamma-glutamyl transferase remained elevated even after 4 months. This case argues for an idiosyncratic cholestatic hepatocellular damage caused by azathioprine.

Clinical pharmacology and pharmacogenetics of thiopurines

The thiopurine drugs-azathioprine (AZA), 6-mercaptopurine (6-MP), and thioguanine-are widely used to treat malignancies, rheumatic diseases, dermatologic conditions, inflammatory bowel disease, and solid organ transplant rejection. However, thiopurine drugs have a relatively narrow therapeutic index and are capable of causing life-threatening toxicity, most often myelosuppression. Thiopurine S-methyltransferase (TPMT; EC 2.1.1.67), an enzyme that catalyzes S-methylation of these drugs, exhibits a genetic polymorphism in 10% of Caucasians, with 1/300 individuals having complete deficiency. Patients with intermediate or deficient TPMT activity are at risk for excessive toxicity after receiving standard doses of thiopurine medications. This report reviews the recent advances in the knowledge of the mechanism of action as well as the molecular basis and interethnic variations of TPMT and inosine triphosphate pyrophosphatase (ITPase; EC 3.6.1.19), another enzyme implicated in thiopurine toxicity. In addition, an update on pharmacokinetics, metabolism, drug-drug interactions, safety, and tolerability of thiopurine drugs is provided.

Pharmacogenetics of immunosuppressive drugs: prospect of individual therapy for transplant patients

The immunosuppressive drugs used in solid-organ transplantation are potent and toxic agents with narrow therapeutic ranges. Underdosing is associated with immunological rejection of the transplanted organ, whereas overdosing results in infections, malignancy and direct toxicity to a number of organs. Pharmacokinetic heterogeneity makes initial dose determination difficult, as there is a poor correlation between dose and blood concentration. Therapeutic drug monitoring is available but the pharmacokinetic–pharmacodynamic association is imperfect and it does not help in achieving target blood concentrations during the critical early 2–3 days after transplantation. Genetic polymorphisms in drug targets, drug-metabolizing enzymes and drug efflux pumps have been identified as potential targets for developing a pharmacogenetic strategy to individualize initial drug choice and dose. To date, use of the CYP3A5 genotype to predict the appropriate initial dose of tacrolimus is the most promising option for individualization of drug therapy in organ transplantation.

Pregnancy outcome of women exposed to azathioprine during pregnancy

BACKGROUND

Azathioprine (AZP) interferes with nucleic acid synthesis and is teratogenic in animals. In view of the paucity of information on the use of AZP during pregnancy we investigated this subject in a prospective, controlled, multicenter study. Our objective was too determine whether exposure to AZP during pregnancy increases the risk for major malformations and to determine the effect on pregnancy outcome.

METHODS

Pregnant women on AZP who contacted one of seven teratogen information services were compared to a cohort of pregnant women who contacted two of the seven teratogen information services and took nonteratogenic treatments during their pregnancy.

RESULTS

Follow-up was completed on 189 women in the AZP group and compared to 230 women in the control group. The rate of major malformations did not differ between groups with six neonates in each; the AZP rate was 3.5% and the control group rate was 3.0% (p = .775; OR 1.17; CI: 0.37, 3.69). The mean birth weight and gestational age were lower in the AZP group (2,995 g vs. 3,252 g [p = .001, difference of mean: 257, 95% CI: 106.3, 408.1] and 37.8 weeks vs. 39.1 weeks [p = .001, difference of mean: 1.3, 95% CI: .5, 2.0], respectively). The AZP group had more cases of prematurity (21.4% vs. 5.2% [p < .001; OR 4.0; 95% CI: 2.0, 8.06]) and low birth weight (23% vs. 6.0% [p < .001; OR 3.81; 95% CI: 2.0, 7.2]).

CONCLUSIONS

These results suggest that AZP (50-100 mg/day) does not triple the rate of birth defects; however, it is associated with lower birth weight, gestational age, and prematurity. Larger studies are needed to confirm these observations.

More epidermal p53 patches adjacent to skin carcinomas in renal transplant recipients than in immunocompetent patients: the role of azathioprine

Immunosuppressive medication in renal transplant recipients (RTR) strongly increases the risk of cancers on sun-exposed skin. This increased risk was considered an inevitable collateral effect of immunosuppression, because UV-induced carcinomas in mice were found to be highly antigenic. Here, we posed the question whether immunosuppression also increases the frequency of p53-mutant foci ('p53 patches'), putative microscopic precursors of squamous cell carcinomas. As the majority of RTR was kept on azathioprine for most of the time, we investigated whether this drug could increase UV-induced p53 patches by immunosuppression. As azathioprine can impair UV-damaged DNA repair under certain conditions, we also investigated whether DNA repair was affected. Archive material of RTR and immunocompetent patients (ICP), as well as azathioprine-administered hairless mice were examined for p53 patches. DNA repair was investigated by ascertaining the effect of azathioprine on unscheduled DNA synthesis (UDS) in UV-irradiated human keratinocytes. P53 patches were more prevalent in RTR than in ICP in normal skin adjacent to carcinomas (P = 0.02), in spite of a lower mean age in the RTR (52 vs 63 years, P = 0.001), but we found no increase in UV-induced p53 patches in mice that were immunosuppressed by azathioprine. We found a significant reduction in DNA repair activity in keratinocytes treated with azathioprine (P = 0.011). UV-induced UDS in humans is dominated by repair of cyclobutane pyrimidine dimers, and these DNA lesions can lead to 'UV-signature' mutations in the P53 gene, giving rise to p53 patches.

Interaction and transport characteristics of mycophenolic acid and its glucuronide via human organic anion transporters hOAT1 and hOAT3

The immunosuppressant mycophenolate mofetil (MMF) is frequently administered with calcineurin inhibitors and corticosteroids to recipients of organ transplantations. However, the renal handling of the active metabolite mycophenolic acid (MPA) and 7-O-MPA-glucuronide (MPAG) has been unclear. The purpose of the present study was to assess the interaction of MPA and MPAG with the human renal organic anion transporters hOAT1 (SLC22A6) and hOAT3 (SLC22A8), by conducting uptake experiments using HEK293 cells stably expressing these transporters. MPA and MPAG inhibited the time-dependent uptake of p-[(14)C]aminohippurate by hOAT1 and that of [(3)H]estrone sulfate by hOAT3. The apparent 50% inhibitory concentration (IC(50)) of MPA for hOAT1 and hOAT3 was estimated at 10.7 and 1.5 microM, respectively. In the case of MPAG, the IC(50) values were calculated at 512.3 microM for hOAT1 and 69.1 microM for hOAT3. Eadie-Hofstee plot analyses showed that they inhibited hOAT1 noncompetitively and hOAT3 competitively. No inhibitory effects of tacrolimus, cyclosporin A and azathioprine on transport of p-[(14)C]aminohippurate by hOAT1 and of [(3)H]estrone sulfate by hOAT3 were observed. No transport of MPA by these transporters was observed. On the other hand, the uptake of MPAG into cells was stimulated by the expression of hOAT3, but not hOAT1. These findings propose the possibility that the administration of MMF decreases the renal clearance of drugs which are substrates of hOAT1 and hOAT3. Present data suggest that hOAT3 contributes to the renal tubular secretion of MPAG.

Thiopurine treatment in inflammatory bowel disease: clinical pharmacology and implication of pharmacogenetically guided dosing

This review summarises clinical pharmacological aspects of thiopurines in the treatment of chronic inflammatory bowel disease (IBD). Current knowledge of pharmacogenetically guided dosing is discussed for individualisation of thiopurine therapy, particularly to avoid severe adverse effects. Both azathioprine and mercaptopurine are pro-drugs that undergo extensive metabolism. The catabolic enzyme thiopurine S-methyltransferase (TPMT) is polymorphically expressed, and currently 23 genetic variants have been described. On the basis of an excellent phenotype-genotype correlation for TPMT, genotyping has become a safe and reliable tool for determination of a patient's individual phenotype. Thiopurine-related adverse drug reactions are frequent, ranging from 5% up to 40%, in both a dose-dependent and -independent manner. IBD patients with low TPMT activity are at high risk of developing severe haematotoxicity if pharmacogenetically guided dosing is not performed. Based on several cost-benefit analyses, assessment of TPMT activity is recommended prior to thiopurine therapy in patients with IBD. The underlying mechanisms of azathioprine/mercaptopurine-related hepatotoxicity, pancreatitis and azathioprine intolerance are still unknown. Although the therapeutic response appears to be related to 6-thioguanine nucleotide (6-TGN) concentrations above a threshold of 230-260 pmol per 8 x 10(8) red blood cells, at present therapeutic drug monitoring of 6-TGN can be recommended only to estimate patients' compliance.Drug-drug interactions between azathioprine/mercaptopurine and aminosalicylates, diuretics, NSAIDs, warfarin and infliximab are discussed. The concomitant use of allopurinol without dosage adjustment of azathioprine/mercaptopurine leads to clinically relevant severe haematotoxicity due to elevated thiopurine levels. Several studies indicate that thiopurine therapy in IBD during pregnancy is safe. Thus, azathioprine/mercaptopurine should not be withdrawn in strictly indicated cases of pregnant IBD patients. However, breastfeeding is contraindicated during azathioprine/mercaptopurine therapy. Use of azathioprine/mercaptopurine for induction and maintenance of remission in corticosteroid-dependent or corticosteroid-refractory IBD, particularly Crohn's disease, is evidence based. To improve response rates in thiopurine therapy of IBD, comprehensive analyses including metabolic patterns and genome-wide profiling in patients with azathioprine/mercaptopurine treatment are required to identify novel candidate genes.

Thiopurine methyltransferase deficiency and azathioprine intolerance in autoimmune hepatitis

Thiopurine methyltransferase deficiency has been associated with intolerance to azathioprine. Our goals were to assess the frequency of enzyme deficiency in autoimmune hepatitis and correlate deficiency states with azathioprine intolerance. Eighty-six patients receiving azathioprine (50-150 mg daily) were evaluated for enzyme activity and azathioprine-related complications. Their findings were compared to 89 similarly treated but untested patients. Thirteen patients (15%) had low thiopurine methyltransferase levels (11.4+/- 0.9 U/ml RBC; range, 3.5-14.9 U/ml RBC). Azathioprine intolerance occurred as commonly in patients with normal or above normal enzyme levels as in patients with below normal levels (12% versus 15%, p = 0.7). Patients treated without enzyme testing had the same frequency of complications (9% versus 13%, p = 0.5) as tested patients. We conclude that routine screening of blood thiopurine methyltransferase levels has a low yield for identifying individual patients at risk for azathioprine toxicity during conventional low dose therapy for autoimmune hepatitis.

Immunomodulatory therapy for ocular inflammatory disease: a basic manual and review of the literature

Corticosteroids are used as first-line treatment for many ocular inflammatory conditions. The risk of adverse effects, however, necessitates conversion to steroid-sparing immunomodulatory therapy (IMT) for disease that is recurrent, chronic, or poorly responsive to treatment. Combination drug treatments with multiple agent 'recipes' are also considered. Immunomodulatory agents include the broad categories of antimetabolites (azathioprine, methotrexate, mycophenolate mofetil), alkylating agents (cyclophosphamide, chlorambucil), T-cell inhibitors (cyclosporine, tacrolimus), and cytokines (interferon alfa). This article reviews and summarizes the evidence for IMT agent use in the treatment of various forms of ocular inflammation.

Effects of azathioprine and its metabolites on repair mechanisms of the intestinal epithelium in vitro

Erosions and ulcerations of the intestinal epithelium are hallmarks of inflammatory bowel diseases (IBD). Intestinal epithelial cell migration (restitution) and proliferation are pivotal mechanisms for healing of epithelial defects after mucosal injury. In addition, the rate of apoptosis of epithelial cells may modulate intestinal wound healing. The purine antagonists azathioprine (AZA) and 6-mercaptopurine (6-MP) are widely used drugs in the treatment of IBD. In the present study, the hitherto unknown effects of AZA as well as its metabolites 6-MP and 6-thioguanine (6-TG) on repair mechanisms and apoptosis of intestinal epithelia were analysed. Intestinal epithelial cell lines (human Caco-2, T-84 and HT-29 cells, rat IEC-6 cells) were incubated with AZA, 6-MP or 6-TG for 24 h (final concentrations 0.1-10 microM). Migration of Caco-2 and IEC-6 cells was analysed by in vitro restitution assays. Caco-2 and IEC-6 cell proliferation was evaluated by measurement of [3H]thymidine incorporation into DNA. Apoptosis of Caco-2, T-84, HT-29 and IEC-6 cells was assessed by histone ELISA, 4'6'diamidino-2'phenylindole-dihydrochloride staining as well as flow cytometric analysis of Annexin V/propidium iodide (PI)-stained cells. Cell cycle progression was evaluated by PI staining and flow cytometry. Epithelial restitution was not significantly affected by any of the substances tested. However, proliferation of intestinal epithelial cells was inhibited in a dose-dependent manner (maximal effect 92%) by AZA, 6-MP as well as 6-TG. In HT-29 cells, purine antagonist-effected inhibition of cell proliferation was explained by a cell cycle arrest in the G2 phase. In contrast, AZA, 6-MP and 6-TG induced no cell cycle arrest in Caco-2, T-84 and IEC-6 cells. AZA, 6-MP as well as 6-TG induced apoptosis in the non-transformed IEC-6 cell line but not in human Caco-2, T-84 and HT-29 cells. In summary, AZA and its metabolites exert no significant effect on intestinal epithelial restitution. However, they profoundly inhibit intestinal epithelial cell growth via various mechanisms: they cause a G2 cell cycle arrest in HT-29 cells, induce apoptosis in IEC-6 cells and dose-dependently inhibit intestinal epithelial proliferation.

The thiopurines: An update

The thiopurine drugs, 6-mercaptopurine (6-MP), 6-thioguanine (6-TG) are commonly used cytotoxic agents. A derivative of 6-MP, azathioprine, is commonly used as an immunosuppressant. A prominent route for the metabolism of these agents is mediated by the enzyme thiopurine methyltransferase (TPMT). This enzyme exhibits considerable inter-individual variation in activity, partly due to the presence of common genetic polymorphisms, which influence cytotoxicity of the thiopurine drugs. Variations in the number of tandem repeats in the 5' promoter region have also been shown to influence TPMT expression in vitro. In this article, we review the impact of variations in TPMT activity on sensitivity to the thiopurine drugs in vitro and also in vivo in terms of their clinical efficacy and toxicity. A possible relationship between TPMT and secondary malignancies is also reviewed.

Mechanisms of action of mycophenolate mofetil

Mycophenolate mofetil (MMF, CellCept) is a prodrug of mycophenolic acid (MPA), an inhibitor of inosine-5'-monophosphate dehydrogenase. MPA depletes guanosine nucleotides preferentially in T and B lymphocytes and inhibits their proliferation, thereby suppressing cell-mediated immune responses and antibody formation. MPA also inhibits the glycosylation and expression of adhesion molecules, and the recruitment of lymphocytes and monocytes into sites of inflammation. MPA depletes tetrahydrobiopterin and decreases the production of nitric oxide by inducible NO synthase without affecting the activity of constitutive NO synthases. Activated macrophages produce NO and superoxide, which combine to generate tissue-damaging peroxynitrite. By these two mechanisms MMF exerts anti-inflammatory activity. Unlike calcineurin inhibitors, MMF is not nephrotoxic and does not induce the production of TGFbeta, which is fibrogenic. MMF does not increase blood pressure, cholesterol levels or triglyceride levels in recipients. MMF reduces acute and chronic rejection in allograft recipients and is efficacious in some nephropathies. Evidence is accumulating that MMF may have clinical utility in some autoimmune disorders.

Cancers et immunosuppression : effet pro- et antitumoral des traitements immunosuppresseurs

Malignancies are an important cause of morbidity and mortality among transplant patients. Tumor genesis is the consequence of non-specific immunosuppression that enhanced oncogenic virus replication, but may also be due to direct effects of immunosuppressants. Steroids are believed not to be involved in cancer genesis, in contrast to azathioprine, well known to reduce DNA repair ability, particularly in skin cells exposed to UV irradiation. Calcineurin inhibitors, cyclosporine and tacrolimus, are involved in tumor development through various mechanisms: they promote B-cell proliferation by increasing T lymphocyte IL6 secretion, decrease DNA repair ability and may be able to promote metastasis spreading by a direct cellular effect that is independent of their effect on the host's immune cells. In vitro anti-tumoral properties of mycophenolate mofetil have not been valided in animal models or in human. The last developed immunosuppressant mTOR inhibitors, sirolimus and everolimus, effectively control the proliferation of various tumor cell lines, promote tumor cell apoptosis and inhibit metastatic tumor growth and angiogenesis in in vivo mouse models by affecting VEGF production and effect. If these antitumoral features are confirmed in human, this new immunosuppressive family will offer the unique opportunity to reduce both the incidence of rejection and cancer in organ transplant recipients.

[Panzytopenia from combination therapy with azathioprin and allopurinol]

Azathioprine has been used in rheumatology for more than twenty years. Indications are collagen diseases with multiorgan involvement, where co-medications are frequently necessary. We describe a patient suffering from pancytopenia following a combination therapy of azathioprine and allopurinol because of lupus erythematodes and diabetic nephropathy with hyperuricemia.

Treatment of inflammatory bowel disease with azathioprine and 6-mercaptopurine

6-Mercaptopurine and azathioprine have become important therapeutic options for patients with inflammatory bowel disease (IBD). Although accumulating data in the literature have supported the use of these immunomodulators in the management of IBD, marked variation exists in the pattern of clinical practice regarding azathioprine or 6-mercaptopurine therapy in patients with IBD. This article provides a critical review of the data on the clinical efficacy and toxicities of 6-mercaptopurine and azathioprine in the management of IBD. Emerging literature on the potential application of pharmacogenetic testing and metabolite monitoring are also discussed.

Treatment of inflammatory bowel disease with azathioprine and 6-mercaptopurine

6-Mercaptopurine and azathioprine have become important therapeutic options for patients with inflammatory bowel disease (IBD). Although accumulating data in the literature have supported the use of these immunomodulators in the management of IBD, marked variation exists in the pattern of clinical practice regarding azathioprine or 6-mercaptopurine therapy in patients with IBD. This article provides a critical review of the data on the clinical efficacy and toxicities of 6-mercaptopurine and azathioprine in the management of IBD. Emerging literature on the potential application of pharmacogenetic testing and metabolite monitoring are also discussed.

Early postoperative complications are not increased in patients with Crohn's disease treated perioperatively with infliximab or immunosuppressive therapy

AIM

The aim was to determine whether the use of steroids, immunosuppressive agents, or infliximab prior to abdominal surgery for Crohn's disease is associated with an increased rate of early postoperative complications.

METHODS

All patients who underwent abdominal surgery for Crohn's disease between October 1998 and December 2001 were identified. Medical records were abstracted for demographics, location and duration of disease, use of infliximab within 8 wk before and 4 wk after surgery, and dose and duration of corticosteroids, azathioprine/6-mercaptopurine, and methotrexate. Steroid use was defined as: high (intravenous or oral >/=40 mg/day), moderate (oral >/=20 mg/day for at least 2 months), low (oral <20 mg/day or oral >20 mg/day for <2 months), or none. Early (within 30 days postinfliximab) septic and nonseptic complications were identified. Septic complications included wound sepsis, intraabdominal, and extraabdominal infections. Nonseptic complications included Crohn's disease recurrence, small bowel obstruction, gastrointestinal bleeding, and thromboembolism. A logistic regression analysis assessed the association between perioperative therapy with infliximab, corticosteroids, or immunosuppressive therapy and subsequent occurrence of septic complications and separately overall complications.

RESULTS

Two hundred and seventy patients were operated upon including 107 patients who received steroids (34 low dose, 34 moderate dose, 43 high dose), 105 patients who received immunosuppressives (64 azathioprine, 38 6-mercaptopurine, 4 methotrexate), and 52 who received infliximab. Forty-eight patients underwent urgent or emergent surgery and 222 underwent elective surgery. Septic complications occurred in 52 of 270 (19%) patients including wound sepsis in 28 (10%), anastomotic leak in 9 (3%), intraabdominal abscess in 5 (2%), and extraabdominal infections in 19 (7%). Nonseptic complications occurred in 18 of 270 (7%) patients. Preoperative use of high- or moderate-dose steroids, immunosuppressives, or infliximab was not associated with greater complication rates. No deaths occurred.

CONCLUSION

Early complications after elective abdominal surgery for CD are not associated with steroid dose, immunosuppressive therapy, or infliximab use.