Use of thiopurines in inflammatory bowel disease: Safety issues

Thiopurines are widely used for maintenance treatment of inflammatory bowel disease. Interindividual variability in clinical response to thiopurines may be attributed to several factors including genetic polymorphisms, severity and chronicity of disease, comorbidities, duration of administration, compliance issues and use of concomitant medication, environmental factors and clinician and patient preferences. The purpose of this review is to summarise the current evidence on thiopurine safety and toxicity, to describe adverse drug events and emphasise the significance of drug interactions, and to discuss the relative safety of thiopurine use in adults, elderly patients, children and pregnant women. Thiopurines are safe to use and well tolerated, however dose adjustment or discontinuation of treatment must be considered in cases of non-response, poor compliance or toxicity. Drug safety, clinical response to treatment and short to long term risks and benefits must be balanced throughout treatment duration for different categories of patients. Treatment should be individualised and stratified according to patient requirements. Enzymatic testing prior to treatment commencement is advised. Surveillance with regular clinic follow-up and monitoring of laboratory markers is important. Data on long term efficacy, safety of thiopurine use and interaction with other disease modifying drugs are lacking, especially in paediatric inflammatory bowel disease. High quality, collaborative clinical research is required so as to inform clinical practice in the future.     

Use of thiopurines in inflammatory bowel disease

The use of thiopurines as immunosuppression for the treatment of refractory or chronic active inflammatory bowel disease is established for both Crohn’s disease and ulcerative colitis.Nevertheless,many questions remain concerning the optimal treatment regimens of azathioprine,6-mercaptopurine and thioguanine.We will briefly summarize dose recommendations,indications for thiopurine therapy and side effects which are relevant in clinical practice.We discuss some currently debated topics,including the combination of azathioprine and allopurinol,switching of thiopurine therapy in case of side effects,the use of azathioprine in pregnancy,the infection risk using thiopurines and the evidence when to stop thiopurines.Excellent reviews have been published on the thiopurine metabolic pathway which will not be discussed here in detail.     

Thiopurine-methyltransferase variants in inflammatory bowel disease:Prevalence and toxicity in Brazilian patients

AIM:To analyze the prevalence of thiopurine-methyltransferase(TPMT)genotypes and their associationwith drug toxicity in inflammatory bowel disease(IBD)patients from southeastern Brazil.METHODS:A total of 219 consecutive patients with IBD,of which 146 had Crohn’s disease and 73 had ulcerative colitis,regularly seen at the outpatient unit of the Division of Gastroenterology at the University Hospital Pedro Ernesto of the State University of Rio de Janeiro,a tertiary referral center,were enrolled in this study from February 2009 to January 2011.We analyzed the presence of major TPMT genetic variants(TPMT*2,*3A,*3C)in IBD patients by means of a specific allele and RFLP-PCR.Genomic DNA was isolated from peripheral blood leukocytes by proteinase-K/Sodium Dodecyl Sulfate digestion and phenol-chloroform extraction.TPMT*2(C238G),TPMT*3A(G460A/A719G),and TPMT*3C(A719G)genotypes were detected by real-time polymerase chain reaction followed by direct sequencing with specific primers.Clinical data were systematically recorded,and correlated with the genotype results.RESULTS:The distribution of the selected TPMT gene polymorphism TPMT*2(C238G),TPMT*3A(G460A/A719G),and TPMT*3C(A719G)genotypes was 3.6%,5.4%,and 7.7%of the patients,respectively.Among the side effects recorded from patients taking azathioprine,14 patients presented with pancreatitis and/or an elevation of pancreatic enzymes,while 6 patients had liver toxicity,and 2 patients exhibited myelosuppression/neutropenia.TPMT polymorphisms were detected in 37/219 patients(8 heterozygous for*2,11 heterozygous for*3A,and 18 heterozygous for*3C).No homozygotic polymorphisms were found.Despite the prevalence of the TPMT*3C genotype,no differences among the genotype frequencies were significant.Although no association was detected regarding myelotoxicity or hepatotoxicity,a trend towards the elevation of pancreatic enzymes was observed for TPMT*2 and TPMT*3C genotypes.CONCLUSION:The prevalence of TPMT genotypes was high among Brazilian patients.Variants genes*2and*3C may be associated with azathioprine pancreatic toxicity in a IBD southeastern Brazilian population.     

TPMT genotype and the use of thiopurines in paediatric inflammatory bowel disease

BACKGROUND: Thiopurines are used in the treatment of inflammatory bowel disease. They are metabolised via methylation by thiopurine-S-methyltransferase (TPMT), which displays a genetically determined polymorphic activity. Subjects with reduced TPMT activity have a higher concentration of active thiopurine metabolites and may be at increased risk of bone-marrow suppression. AIMS: To evaluate the relevance of TPMT genotyping in the management of thiopurines therapy in inflammatory bowel disease patients. PATIENTS AND METHODS: Adverse effects and clinical response were determined retrospectively and correlated with TPMT genotype in 70 paediatric inflammatory bowel disease patients. RESULTS: Nineteen patients (27.1%) developed adverse effects; of the 51 who did not, 34 (66.7%) responded to treatment. Five patients (7.1%) were heterozygous for a variant TPMT allele; two of these (40%) were intolerant to thiopurines, compared to 17 of the 65 patients (26.2%) with a wild type gene (O.R. 1.88, 95% CI 0.29-12.2, p=0.61); among the 34 responders, the median dosage of the drug required to obtain remission was lower for mutated than for wild type patients (1.6mgkg(-1)day(-1) versus 2.0mgkg(-1)day(-1), p=0.043). CONCLUSIONS: There was no significant association between adverse effects of thiopurines and TPMT heterozygous genotype, but TPMT genotyping could be useful in establishing the most appropriate dose of thiopurines to start treatment.     

The use of thiopurines for the treatment of inflammatory bowel diseases in clinical practice

BACKGROUND: Thiopurines are the most commonly used immunomodulatory drugs in inflammatory bowel diseases. AIM: To evaluate the use, the therapeutic and safety profiles of thiopurines in a large sample of IBD patients. METHODS: We reviewed 3641 case histories of IBD patients. Thiopurines were prescribed in 582 patients (16.0%); the analysis was performed on the 553 (267 ulcerative colitis, 286 Crohn's disease) with exhaustive clinical data. RESULTS: The main indications for treatment were steroid-dependence (328/553, 59.3%) and steroid-resistance (113/553, 20.7%). Thiopurines were started when CD were younger than UC patients (p<0.001) but earlier from diagnosis in UC than in CD patients (p=0.003). Efficacy was defined as optimal (258/553, 46.6%), partial (108/553, 19.5%), absent (85/553, 15.4%) and not assessable (102/553, 18.4%). Efficacy was independent of disease type, location/extension or duration and age at starting. Side effects were observed in 151/553 (27.3%) patients, leading to drug discontinuation in 101 (18.3%). 15 out of the 130 (11.5%) patients who took thiopurines for more than 4 years relapsed, more frequently in CD than in UC (OR=3.67 95% C.I. 0.98-13.69; p=0.053). CONCLUSIONS: Thiopurines confirm their clinical usefulness and acceptable safety profile in managing complicated IBD patients. The majority of patients treated for longer than 4 years maintain response. No clinical and demographic predictive factors for efficacy and side effects were identified.     

Thiopurines and inflammatory bowel disease: Current evidence and a historical perspective

The use of thiopurines in inflammatory bowel disease(IBD) has been examined in numerous prospective, controlled trials, with a majority demonstrating a clinical benefit. We conducted this review to describe the historical and current evidence in the use of thiopurines in IBD. A systematic search was performed on MEDLINE between 1965 and 2016 to identify studies on thiopurines in IBD. The most robust evidence for thiopurines in IBD includes induction of remission in combination with anti-tumor necrosis factor(antiTNF) agents, and maintenance of remission and postoperative maintenance in Crohn's disease. Less evidence exists for thiopurine monotherapy in induction of remission, maintenance of ulcerative colitis, chemoprevention of colorectal cancer, and in preventing immunogenicity to anti-TNF. Evidence was often limited by trial design. Overall, thiopurines have demonstrated efficacy in a broad range of presentations of IBD. With more efficacious novel therapeutic agents, the positioning of thiopurines in the management of IBD will change and future studies will analyze the benefit of thiopurines alone and in conjunction with these new medications.     

Common misconceptions about 5-aminosalicylates and thiopurines in inflammatory bowel disease

Misconceptions are common in the care of patients with inflammatory bowel disease(IBD).In this paper,we state the most commonly found misconceptions in clinical practice and deal with the use of 5-aminosalicylates and thiopurines,to review the related scientificevidence,and make appropriate recommendations.Prevention of errors needs knowledge to avoid making such errors through ignorance.However,the amount of knowledge is increasing so quickly that one new danger is an overabundance of information.IBD is a ...     

Therapeutic drug monitoring in patients with inflammatory bowel disease

Thiopurine analogs and anti-tumor necrosis factor(TNF)agents have dramatically changed the therapeutics of inflammatory bowel diseases(IBD),improving short and long-term outcomes.Unfortunately some patients do not respond to therapy and others lose response over time.The pharmacokinetic properties of these drugs are complex,with high inter-patient variability.Thiopurine analogs are metabolized through a series of pathways,which vary according to the patients’pharmacogenetic profile.This profile largely determines the ratios of metabolites,which are in turn associated with likelihoods of clinical efficacy and/or toxicity.Understanding these mechanisms allows for manipulation of drug dose,aiming to reduce the development of toxicity while improving the efficacy of treatment.The efficacy of anti-TNF drugs is influenced by many pharmacodynamic variables.Several factors may alter drug clearance,including the concomitant use of immunomodulators(thiopurine analogs and methotrexate),systemic inflammation,the presence of anti-drug antibodies,and body mass.The treatment of IBD has evolved with the understanding of the pharmacologic profiles of immunomodulating and TNF-inhibiting medications,with good evidence for improvement in patient outcomesobserved when measuring metabolic pathway indices.The role of routine measurement of metabolite/drug levels and antibodies warrants further prospective studies as we enter the era of personalized IBD care.     

Thiopurine methyltransferase activity combined with 6-thioguanine metabolite levels predicts clinical response to thiopurines in patients with inflammatory bowel disease

BACKGROUND/AIMS: 6-Mercaptopurine and its prodrug azathioprine are effective for the treatment of inflammatory bowel disease. Thiopurine methyltransferase is important for the metabolism of thiopurines. However, there is controversy as to the clinical utility of measuring thiopurine methyltransferase enzyme activity and 6-thioguanine nucleotide levels. Our aim was to determine if thiopurine methyltransferase enzyme activity and 6-thioguanine nucleotide level monitoring would predict response to therapy with thiopurines in patients with inflammatory bowel disease. METHODS: Baseline thiopurine methyltransferase enzyme activity prior to initiation of therapy with either 6-mercaptopurine or azathioprine was determined in 39 patients with inflammatory bowel disease. The association between clinical response and thiopurine methyltransferase activity and 6-thioguanine nucleotide levels singly or in combination were analysed. RESULTS: Seventeen of 39 patients (44%) responded to 6-mercaptopurine or azathioprine therapy. Thiopurine methyltransferase enzyme activity below the mean of 30.5 U was significantly associated with clinical response. The thiopurine methyltransferase low phenotype was associated with response in 65% vs. 29% in individuals with thiopurine methyltransferase enzyme activity above 30.5 U (p = 0.05). There was no correlation between thiopurine methyltransferase activity and 6-thioguanine nucleotide levels. The maximal 6-thioguanine nucleotide levels did not predict clinical response. When combining thiopurine methyltransferase enzyme activity and 6-thioguanine nucleotide levels, the combination of thiopurine methyltransferase low/6-thioguanine nucleotide high was associated with response in 7/7 (100%) vs. only 2/8 (25%) with the combination of thiopurine methyltransferase high/6-thioguanine nucleotide low (p=0.01). CONCLUSIONS: Thiopurine methyltransferase activity inversely correlated with clinical response to thiopurine treatment in inflammatory bowel disease. Thiopurine methyltransferase enzyme activity below 30.5 U combined with a post-treatment 6-thioguanine nucleotide level > 230 pmol/8 x 10(8) erythrocytes was the best predictor of response.     

Optimizing 6-mercaptopurine and azathioprine therapy in the management of inflammatory bowel disease

The thiopurine drugs,6-mercaptopurine(6-MP) and azathioprine,are efficacious in the arsenal of inflammatory bowel disease(IBD) therapy.Previous reports indicate that 6-thioguanine nucleotide(6-TGN) levels correlate with therapeutic efficacy,whereas high 6-methylmercaptopurine(6-MMP) levels are associated with hepatotoxicity and myelotoxicity.Due to their complex metabolism,there is wide individual variation in patient response therein,both in achieving therapeutic drug levels as well as in developing advers...     

Thiopurines are an independent risk factor for active tuberculosis in inflammatory bowel disease patients

The use of thiopurines is an independent risk factor for active tuberculosis in patients with inflammatory bowel disease.     

Current use of immunosuppressive agents in inflammatory bowel disease patients in East China

AIM： To investigate immunosuppressive agents used to treat inflammatory bowel disease （IBD） in East China.
METHODS： A retrospective review was conducted, involving 227 patients with IBD admitted to Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University from June 2000 to December 2007, Data regarding demographic, clinical characteristics and immunosuppressants usage were analyzed,
RESULTS： A total of 227 eligible patients were evaluated in this study, including 104 patients with Crohn＇s disease and 123 with ulcerative colitis. Among the patients, 61 had indications for immunosuppressive agents use. However, only 21 （34.4%） received immunosuppressive agents. Among the 21 patients, 6 （37.5%） received a subtherapeutic dose of azathioprine with no attempt to increase the dosage. Of the 20 patients that received immunosuppressive agent treatment longer than 6 mo, 15 patients went into remission, four patients were not affected and one relapsed. Among these 20 patients, four patients suffered from myelotoxicity and one suffered from hepatotoxicity.
CONCLUSION： Immunosuppressive agents are used less frequently to treat IBD patients from East China compared with Western countries. Monitoring immunosuppressive agent use is recommended to optimize dispensation of drugs for IBD in China.     

Long term efficacy and safety of allopurinol and azathioprine or 6-mercaptopurine in patients with inflammatory bowel disease

Background and aimsWe previously reported that IBD patients who are non-responders to thiopurines with preferential shunting of metabolites to hepatotoxic 6-methylmercaptopurine ribonucleotides compared to 6-thioguanine nucleotides can reverse the ratio of 6-MMP/6-TGN and respond to thiopurines with the addition of allopurinol. The objective of this study is to report long term efficacy and safety, along with results for an additional 11 patients.MethodsRetrospective chart review of patients at the University of Chicago IBD Center treated with allopurinol in addition to thiopurines.ResultsTwenty five patients with Crohn's disease or ulcerative colitis were enrolled. Within the first month of therapy 6-TGN metabolite levels increased from a mean of 186.5 ± 17.4 (SE) to 352.8 ± 37.8 pmol/8 × 10⁸ (p = 0.0001). Over the same period 6-MMP levels decreased from a mean of 11,966 ± 1697 to 2004 ± 536 pmol/8 × 10⁸ (p < 0.0001). The mean daily dosage of prednisone decreased from 19.8 ± 3.8 mg to 5.3 ± 2.7 mg (p = 0.03). Thirteen patients have a minimum of one year follow-up. Nine of these thirteen patients have continued on therapy for at least 2 years. All thirteen of these patients continue to be in clinical remission at the last follow-up visit. No patients have had evidence of sustained thrombocytopenia or abnormal liver enzymes.ConclusionsIn AZA/6-MP non-responders with increased 6-MMP/6-TGN ratios, addition of allopurinol continues to demonstrate safety and efficacy for long-term maintenance and steroid-sparing in IBD.     

MicroRNAs与炎症性肠病

炎症性肠病(IBD)的发病机制与免疫、炎症、损伤、遗传等因素密切相关。MicroRNAs是一类小的非编码RNA,其通过与靶基因3’UTR区结合,负向调控基因表达,在炎症性肠病的发病机制中发挥重要的作用。     

Declining use of combination infliximab and immunomodulator for inflammatory bowel disease in the community setting

AIM To describe trends of combination therapy (CT) of infliximab (IFX) and immunomodulator (IMM) for inflammatory bowel disease(IBD) in the community setting. METHODS A retrospective study was conducted of all IBD patients referred for IFX infusion to our community infusion center between 04/01/01 and 12/31/14. CT was defined as use of IFX with either azathioprine, 6-mercaptopurine, or methotrexate. We analyzed trends of CT usage overall, for Crohn's disease (CD) and ulcerative colitis (UC), and for the subgroups of induction patients. We also analyzed the trends of CT use in these groups over the study period, and compared the rates of CT use prior to and after publication of the landmark SONIC trial.RESULTS Of 258 IBD patients identified during the 12 year study period, 60 (23.3%) received CT, including 35 of 133(26.3%) induction patients. Based on the CochranArmitage trend test, we observed decreasing CT use for IBD patients overall(P 0.0001) and IBD induction patients,(P = 0.0024). Of 154 CD patients, 37(24.68%) had CT, including 20 of 77 (26%) induction patients.The Cochran Armitage test showed a trend towards decreasing CT use for CD overall(P 0.0001) and CD induction,(P = 0.0024). Overall, 43.8% of CD patients received CT pre-SONIC vs 7.4% post-SONIC (P 0.0001). For CD induction, 40.0% received CT preSONIC vs 10.8% post-SONIC(P = 0.0035). Among the 93 patients with UC, 19 (20.4%) received CT. Of 50 induction patients, 14 (28.0%) received CT. The trend test of the 49 patients with a known year of induction again failed to demonstrate any significant trends in the use of CT(P = 0.6). CONCLUSION We observed a trend away from CT use in IBD. A disconnect appears to exist between expert opinion and evidence favoring CT with IFX and IMM, and evolving community practice.     

Thiopurines in inflammatory bowel disease revisited

Although a great variety of new drugs have been introduced for the therapy of inflammatory bowel diseases so far,a definite cure of the disease is still out of scope.An anti-inflammatory approach to induce remission followed by maintenance therapy with immunosupressants is still the mainstay of therapy.Thiopurines comprising azathioprine and its active metabolite mercaptopurine as well as tioguanine,are widely used in the therapy of chronic active inflammatory bowel disease(IBD).Their steroid sparing potential and efficacy in remission maintenance are out of doubt.Unfortunately,untoward adverse events are frequently observed and may preclude further administration or be life threatening.This review will focus on new aspects of thiopurine therapy in IBD,its efficacy and safety.