thioguanine-anhydrous and Hepatitis--Autoimmune

The utility of measuring thiopurine metabolites (TM) to individualize therapy in autoimmune hepatitis (AIH) has not been defined, and the evidence regarding its use in clinical practice is heterogeneous. This systematic review and meta-analysis aimed to compare the mean concentration of TM between patients in biochemical remission and those not in remission.. A systematic literature search was conducted using PubMed, Scopus, the Cochrane Library, and Google Scholar for keywords related to TM and AIH. Two reviewers independently searched and selected studies comparing the levels of 6-methyl mercaptopurine (6-MMP) and 6-thioguanine nucleotide (6-TGN) and their ratio in cases of AIH in remission and otherwise. Meta-analysis was performed by calculating the weighted mean difference using the inverse variance heterogeneity model.. A total of 1066 records were identified through systematic search; of which, 7 (n = 3 pediatric, n = 4 adults) were considered for inclusion, and 442 TM measurements (n = 128 in children) were analyzed. Mean 6-TGN levels were significantly higher among patients in remission than in those who were not, with a pooled weighted mean difference (WMD) of 15.67 [95% confidence interval (CI), 6.68-24.66] pmol/8 × 108 red blood cells (RBC). The difference was higher in the pediatric age group (WMD, 56.11; 95% CI, 13.60-98.62) than in adults (WMD, 13.77; 95% CI, 4.58-22.97). There was no significant difference in the 6-MMP levels (WMD, -431.7; 95% CI, -1237.4 to 373.9 pmol/8 × 108 RBC; I2 = 82%; n = 3 studies) or 6-MMP/6-TGN ratio among the patients who were in biochemical remission and those who were not (WMD, -0.97; 95% CI, -5.77 to 3.84; I2 = 82%; n = 3 studies).. This meta-analysis suggests a link between 6-TGN levels and biochemical remission in AIH. Further high-quality studies are required to determine the therapeutic cutoff of 6-TGN.

Topics: Adult; Azathioprine; Child; Hepatitis, Autoimmune; Humans; Immunosuppressive Agents; Mercaptopurine; Thioguanine

Thiopurines in combination with glucocorticoids are used as first-line, second-line and maintenance therapies in autoimmune hepatitis and opportunities exist to improve and expand their use.. To describe the metabolic pathways and key factors implicated in the efficacy and toxicity of the thiopurine drugs and to indicate the opportunities to improve outcomes by monitoring and manipulating metabolic pathways, individualising dosage and strengthening the response.. English abstracts were identified in PubMed by multiple search terms. Full-length articles were selected for review, and secondary and tertiary bibliographies were developed.. Thiopurine methyltransferase activity and 6-tioguanine (6-thioguanine) nucleotide levels influence drug efficacy and safety, and they can be manipulated to improve treatment response and prevent myelosuppression. Methylated thiopurine metabolites are associated with hepatotoxicity, drug intolerance and nonresponse and their production can be reduced or bypassed. Universal pre-treatment assessment of thiopurine methyltransferase activity and individualisation of dosage to manipulate metabolite thresholds could improve outcomes. Early detection of thiopurine resistance by metabolite testing, accurate estimations of drug onset and strength by surrogate markers and adjunctive use of allopurinol could improve the management of refractory disease. Dose-restricted tioguanine (thioguanine) could expand treatment options by reducing methylated metabolites, increasing the bioavailability of 6-tioguanine nucleotides and ameliorating thiopurine intolerance or resistance.. The efficacy and safety of thiopurines in autoimmune hepatitis can be improved by investigational efforts that establish monitoring strategies that allow individualisation of dosage and prediction of outcome, increase bioavailability of the active metabolites and demonstrate superiority to alternative agents.

Topics: Allopurinol; Azathioprine; Drug-Related Side Effects and Adverse Reactions; Guanine Nucleotides; Hepatitis, Autoimmune; Humans; Inflammatory Bowel Diseases; Mercaptopurine; Purines; Quality Improvement; Thioguanine; Thionucleotides; Treatment Outcome

Nonstandard drugs that target critical pathogenic pathways or immune regulatory mechanisms constitute the next generation of treatments for autoimmune hepatitis. Mycophenolate mofetil impairs the proliferation of lymphocytes, decreases autoantibody production, and induces apoptosis of activated immunocytes. Patients treated for azathioprine intolerance improve more frequently than patients treated for refractory liver disease (54% versus 10%), and mycophenolate mofetil is emerging as a rescue therapy for this population. Complete corticosteroid withdrawal is possible in 40% of patients treated with mycophenolate mofetil, and the frequency of side effects ranges from 3-34%. Budesonide in combination with azathioprine has normalized liver tests more frequently (47% versus 18%) and with fewer side effects (28% versus 53%) than standard therapy after 6 months. Budesonide is emerging as a frontline treatment in non-cirrhotic patients with uncomplicated disease or contraindications to conventional corticosteroids. Cyclosporine and tacrolimus are effective salvage agents for steroid-refractory disease, but side effects have been common and occasionally serious. The 6- thioguanine nucleotides and rapamycin are feasible treatments for autoimmune hepatitis, but 6-thioguanine has major obstacles to overcome, especially the risk of liver toxicity or nodular regenerative hyperplasia. The nonstandard drug therapies emerging for autoimmune hepatitis reflect the need to supplement or supplant current treatment regimens. None has been licensed for use in autoimmune hepatitis, and their applications have been based on results from small singlecenter experiences.

Topics: Animals; Budesonide; Cyclosporine; Drug Discovery; Hepatitis, Autoimmune; Humans; Immunosuppression Therapy; Mycophenolic Acid; Tacrolimus; Thioguanine

The management of autoimmune hepatitis (AIH) continues to be refined. However, several issues remain unresolved, primarily as a consequence of the low incidence of the disease. This factor has contributed both to a lack of understanding of and a paucity of large scale clinical trials involving therapeutic agents.. To summarize the latest evidence regarding the pathogenesis, diagnosis, therapy and long-term management of AIH with a focus on clinical aspects of the disease.. We searched PUBMED for articles pertaining to AIH, its pathogenesis, treatment and clinical outcomes, combined with the authors' own knowledge of the literature.. Standard therapy (corticosteroids and azathioprine) is effective in more than 80% of patients which renders study of novel agents difficult. Budesonide appears to show equivalence to prednisolone. Available, but limited, data suggest that mycophenolate mofetil, tacrolimus and ciclosporin are all variably effective second line agents. Patients with AIH and cirrhosis are at risk of hepatocellular carcinoma (HCC) and require screening. Patients with end stage liver disease represent excellent candidates for liver transplantation.. Despite ongoing limitations in the understanding of pathogenesis and difficulties in evaluating novel therapies, the management of AIH continues to evolve slowly. Multi-centre collaboration is necessary to obtain sufficient patient numbers to undertake good quality therapeutic studies.

Topics: Algorithms; Biomarkers; Female; Hepatitis, Autoimmune; Humans; Immunosuppressive Agents; Liver Failure; Liver Transplantation; Male; Pregnancy; Pregnancy Complications; Secondary Prevention; Thioguanine

The use of corticosteroids in autoimmune hepatitis is an established therapy. To avoid the possible serious side effects of corticosteroids, immunosuppression with azathioprine is often warranted. Azathioprine, a purine analogue, is frequently used to taper or replace corticosteroids. However, approximately 10% of the patients are intolerant to azathioprine. Alternative therapies using mycophenolate, tacrolimus, budesonide, cyclosporine and 6-mercaptopurine have been studied, with variable results. The use of 6-thioguanine, an agent more directly leading to the down-stream active metabolites of azathioprine (6-thioguanine nucleotides) in inflammatory bowel disease patients intolerant to azathioprine or 6-mercaptopurine showed conflicting results. We report three patients with autoimmune hepatitis who could not tolerate azathioprine but tolerated 6-thioguanine 0.3 milligram per kilogram daily well. All three patients improved clinically. Therapeutic drug monitoring was performed. The prospective evaluation of 6-thioguanine as a possible immunosuppressive drug in autoimmune hepatitis patients is warranted.

Topics: Aged; Aged, 80 and over; Azathioprine; Female; Hepatitis, Autoimmune; Humans; Immunosuppressive Agents; Liver Function Tests; Male; Middle Aged; Prednisone; Thioguanine

Topics: Aged; Anti-Inflammatory Agents; Drug-Related Side Effects and Adverse Reactions; Female; Hepatitis, Autoimmune; Humans; Male; Middle Aged; Thioguanine; Treatment Outcome

Azathioprine (AZA) and mercaptopurine (MP) are the cornerstone of steroid-sparing strategies in autoimmune hepatitis (AIH). Up to 20% of patients do not tolerate or respond to these regimens.. To evaluate retrospectively the tolerability and efficacy of tioguanine (thioguanine) (TG) therapy in selected patients with AIH and AIH variant syndromes.. Records of 52 patients who received TG therapy were retrieved from nine hospitals in the Netherlands. Indications for TG treatment were intolerable side effects on AZA or MP (n = 38), insufficient response (n = 11) or first-line treatment (n = 3). Treatment efficacy was defined as normalisation of serum aminotransferases and serum immunoglobulin G.. No serious adverse events occurred in patients treated with TG during a median follow-up of 18 months (range 1-194). Treatment was well tolerated in 41 patients (79%), whereas four had tolerable (8%) and seven (13%) intolerable side effects. Thirty-eight patients were treated with TG after intolerable side effects on AZA or MP; 29 patients continued TG therapy of whom 24 (83%) achieved complete biochemical remission, four (14%) had incomplete and one (3%) had no response; nine discontinued treatment. Seven of 11 patients with insufficient response to AZA or MP were responsive to TG, three with complete and four with incomplete biochemical remission; four discontinued due to intolerance (n = 2) and non-response (n = 2). TG was effective in all AIH patients as first-line maintenance treatment.. In our retrospective review of TG therapy in selected patients with AIH or AIH variants who previously failed on AZA or MP, TG appeared tolerable with biochemical efficacy.

Topics: Adolescent; Adult; Aged; Azathioprine; Biomarkers; Child; Drug-Related Side Effects and Adverse Reactions; Female; Hepatitis, Autoimmune; Humans; Immunosuppressive Agents; Male; Mercaptopurine; Middle Aged; Netherlands; Remission Induction; Retrospective Studies; Thioguanine; Treatment Outcome; Young Adult

Autoimmune hepatitis (AIH) is a common pediatric liver disease and long-term remission is usually maintained with azathioprine (AZA). There is no consensus on the target range for AZA active metabolite 6-thioguanine (6-TGN) levels in pediatric AIH. The aim of the present study was to characterize the outcomes of pediatric patients with AIH and determine correlations between AZA dosing or 6-TGN metabolite levels and biochemical remission.. A retrospective chart review was performed and data on presentation, laboratories including AZA metabolite levels, medication use, and outcomes were collected.. Between 2002 and 2013, 66 children with AIH were identified (mean age at diagnosis 9.6 ± 5.1 years) with a mean follow-up period of 2.9 ± 3.2 years. Common presenting symptoms included jaundice, fatigue, and abdominal pain. The majority of subjects received steroids for induction and AZA for maintenance of remission. Seventy-nine percent achieved biochemical remission (mean time to remission 6.2 ± 9.2 months), 14% were in the induction phase of therapy, 6% required liver transplantation, and 18% were weaned off immunosuppression and remained in remission. 6-TGN levels ranging from 50 to 250 pmol/8 × 10 red blood cell count were associated with biochemical remission (alanine aminotransferase levels of ≤50 U/L).. The vast majority of children with AIH maintain a sustained remission with AZA monotherapy. Biochemical remission was maintained with 6-TGN levels much lower than that recommended for inflammatory bowel disease. These findings suggest that patients should be maintained at the lowest AZA dose possible that is associated with biochemical remission.

Topics: Adolescent; Azathioprine; Biomarkers; Child; Child, Preschool; Female; Follow-Up Studies; Hepatitis, Autoimmune; Humans; Immunosuppressive Agents; Induction Chemotherapy; Maintenance Chemotherapy; Male; Retrospective Studies; Thioguanine; Treatment Outcome

Ten percent of patients with autoimmune hepatitis (AIH) are nonresponsive or intolerant to thiopurine therapy. A skewed metabolism, leading to the preferential generation of (hepato)toxic thiopurine metabolites (6-MMPs) instead of the metabolic active 6-tioguanine (thioguanine) nucleotides (6-TGNs), may explain this unfavourable outcome. Co-administration of allopurinol to low-dose thiopurine therapy may effectively revert this deviant metabolism, as has been shown in inflammatory bowel disease.. To describe the effect of adding allopurinol to low-dose thiopurine therapy in patients with AIH with intolerance or nonresponse to normal thiopurine dosages due to a skewed metabolism.. We describe the clinical efficacy and tolerability of allopurinol-thiopurine combination therapy with allopurinol 100 mg and low-dose thiopurine (25-33% of the original dosage) in eight AIH patients with a skewed thiopurine metabolism. Patients were switched because of dose-limiting intolerance (n = 3), nonresponse (n = 3) or loss of response (n = 2) to conventional thiopurine treatment.. All eight patients showed biochemical improvement with a reduction in median alanine aminotransferase (ALT) levels of 62 U/L at start to 35 U/L at 1 month (P = 0.03). This clinical benefit was sustained in seven patients. Allopurinol-thiopurine combination therapy effectively bypassed thiopurine side effects in four of five patients. Median 6-tioguanine nucleotides levels increased from 100 to 200 pmol/8 × 10(8) red blood cells (RBC) at 3 months (P = 0.04). Median 6-MMP levels decreased in all patients from 6090 to 175 pmol/8 × 10(8) RBC (P = 0.01).. Allopurinol safely and effectively optimises thiopurine therapy in patients with autoimmune hepatitis with intolerance and/or nonresponse due to an unfavourable thiopurine metabolism.

Topics: Adult; Aged; Alanine Transaminase; Allopurinol; Antimetabolites; Drug Interactions; Drug Therapy, Combination; Female; Hepatitis, Autoimmune; Humans; Male; Mercaptopurine; Methyltransferases; Middle Aged; Salvage Therapy; Thioguanine

Corticosteroids alone or in conjunction with azathioprine (AZA) is the standard treatment in autoimmune hepatitis (AiH). Individual variations in thiopurine (TP) metabolism may affect both drug efficacy and toxicity. Our aim was to investigate the utility of thiopurine methyltransferase (TPMT) as well as thioguanine nucleotide (TGN) and methylthioinosine monophosphate (meTIMP) metabolite measurements with regard to clinical outcome.. Two hundred thirty-eight patients with AiH were included in this cross-sectional study. TPMT status was assessed in all patients, while TGN and meTIMP were measured in patients with ongoing TP medication. Clinical outcome was evaluated by liver tests and the ability to withdraw steroids.. TPMT genotyping (n=229) revealed 207 (90.4%) wild-type and 22 heterozygous patients. One hundred forty-three patients had ongoing TP therapy with AZA (n=134) or mercaptopurine (MP; n=9); response was judged as complete response (CR) in 113 patients and partial response (PR) in 30 patients. Both TP dose (1.64 vs 1.19 mg/kg; p=0.012) and TPMT activity (14.3 vs 13.5; p=0.05) were higher in PR, resulting in similar TGN levels (PR: 121 pmol/8 x 10(8) red blood cells [RBC]; CR: 113 pmol/8 x 10(8) RBC; p=0.33) but higher meTIMP levels in PR (1350 vs 400 pmol/8 x 10(8) RBC; p=0.004). Patients able to withdraw steroids or who were using 5 mg prednisolone daily were treated with lower TP doses than patients on higher steroid doses (1.15 vs 1.18 vs 1.82 mg/kg; p<0.001).. TP metabolite measurements are of clinical value in AiH patients who do not respond to standard TP treatment and for the identification of a shifted metabolism, which may demand an alternative treatment strategy.

Topics: Adrenal Cortex Hormones; Adult; Aged; Azathioprine; Biomarkers; Cross-Sectional Studies; Female; Follow-Up Studies; Hepatitis, Autoimmune; Humans; Male; Methyltransferases; Middle Aged; Prognosis; Thioguanine; Thioinosine; Thionucleotides; Treatment Outcome

Azathioprine is commonly used in the treatment of autoimmune hepatitis (AIH). Few data are available on drug monitoring of azathioprine metabolites in patients with AIH, especially in pediatric patients. The purpose of this study was to investigate intracellular thiopurine metabolites in children with AIH and to assess the relevance of drug monitoring compared with the efficacy and toxicity. Data from 28 patients with AIH treated by azathioprine for at least 3 months were recorded. 6-Thioguanine nucleotides (6-TGN) and 6-methyl mercaptopurine nucleotides (6-MeMPN) concentrations and TPMT activity were determined by high-performance liquid chromatography. Blood cell counts and liver function tests were also collected and the clinical outcome was documented. A wide interindividual variability in 6-TGN and 6-MeMPN concentrations was observed with values ranging from 51 to 1966 pmol/8 x 10(8) red blood cells (RBCs) for 6-TGN and from 42 to 8189 pmol/8 x 10(8) RBCs for 6-MeMPN. A total of 61.4% of the patients achieved remission and only 32.6% of these children had 6-TGN values within the target range proposed for inflammatory bowel disease (250-450 pmol/8 x 10(8) red blood cells). No difference in metabolite concentrations was observed between children in remission and those with active disease. Azathioprine dosage was significantly related to 6-TGN and 6-MeMPN levels (r = 0.308, P < 0.001 and r = 0.405, P < 0.001, respectively). A significant negative correlation was observed between 6-TGN concentrations and erythrocyte and lymphocyte counts, whereas 6-MeMPN was not related to blood cell counts. Although leukocyte counts were not related to 6-TGN concentrations, patients with leucopenia exhibited higher 6-TGN values than those without leucopenia (median values 438 pmol/8 x 10(8) RBCs versus 405 pmol/8 x 10(8) RBCs, respectively). Thiopurine metabolite monitoring appears useful in identifying the myelotoxicity and the hepatotoxicity as a result of azathioprine with disease recurrence and to assess adherence to therapy. A further larger study will be required to confirm the optimal recommended target for thiopurine metabolites to achieve remission in patients with AIH.

Topics: Adolescent; Adrenal Cortex Hormones; Anti-Inflammatory Agents; Azathioprine; Biotransformation; Blood Cell Count; Child; Child, Preschool; Chromatography, High Pressure Liquid; Drug Monitoring; Drug Therapy, Combination; Female; Hepatitis, Autoimmune; Humans; Immunosuppressive Agents; Liver Function Tests; Male; Mercaptopurine; Thioguanine

Individualised doses of azathioprine (AZA) may be prescribed by monitoring the levels of the enzyme thiopurine methyltransferase (TPMT). The measurements of thiopurine metabolites of AZA, 6-thioguanine (6-TGN) and 6-methylmercaptopurine (6-MMP), have also been reported as new markers of AZA activity.. To describe TPMT phenotype in our population and to establish a relationship between thiopurine metabolites,and therapeutic activity and adverse effects.. Data on TPMT were retrospectively collected from 107 patients, and 6-TGN and 6-MMP levels in 18 patients currently on treatment with AZA (Crohn's disease 5, ulcerative colitis 5, autoimmune hepatitis 5).. Mean value of TPMT was 20.19U/ml. None of the patients had a TPMT activity<5U/ml. Of the 18 patients on treatment, 13 showed sub-therapeutic levels of 6-TGN (<235pmol/8x10(8) red blood cells). Clinical remission was maintained in 45% of patients. Mean levels of 6-TGN in patients with clinical remission were 259pmol/8x10(8) red blood cells versus 209pmol/8x10(8) red blood cells in non-responders (p=0.37). There was an inverse relationship (r=-0.28) between TPMT and 6-TGN levels. Toxic effects occurred in 6 of 18 patients, with leukopenia in 5 and hyperamylasemia in 1.. Determination of TPMT and monitoring of thiopurine metabolites allows AZA treatment to be optimised, although further studies are necessary to establish therapeutic effectiveness and toxicity ranges.

Topics: Adolescent; Azathioprine; Female; Hepatitis, Autoimmune; Humans; Immunosuppressive Agents; Inflammatory Bowel Diseases; Male; Mercaptopurine; Methyltransferases; Retrospective Studies; Thioguanine

Azathioprine is a key drug in the management of autoimmune hepatitis (AIH), with effects mediated via conversion to 6-thioguanine (6-TG) and 6-methylmercaptopurine (6-MMP), the latter controlled by thiopurine methyltransferase (TPMT). Our aims were to evaluate the role of TPMT genotyping and phenotyping and to examine 6-TG and 6-MMP metabolite levels in patients with AIH.. TPMT genotyping and phenotyping was performed on 86 patients with AIH, and metabolites evaluated in assessable patients.. Eighty-six patients with AIH received azathioprine; 22 developed toxicity and 4/22 were heterozygous for TPMT alleles. Cirrhosis was more common amongst patients who developed toxicity (12/22 (54.5%) versus 19/64 (29.6%), P=0.043). Patients who required persistent prednisone at equivalent azathioprine doses had a higher mean fibrosis stage (P=0.044). TPMT activity, but not metabolites, was lower in patients with stage III/IV fibrosis versus stage I/II fibrosis (30+/-1.92 versus 35.2+/-1.93, P=0.044). Azathioprine dose significantly correlated with measured 6-TG levels (r=0.409, P<0.0001) and 6-MMP levels (r=0.387, P<0.001).. Advanced fibrosis but not TPMT genotype or activity predicts azathioprine toxicity in AIH. Overlap in 6-TG and 6-MMP metabolite levels is noted whether or not steroid therapy is used to maintain remission.

Topics: Adolescent; Adult; Aged; Anti-Inflammatory Agents; Azathioprine; Drug Monitoring; Female; Genotype; Hepatitis, Autoimmune; Humans; Immunosuppressive Agents; Liver; Liver Cirrhosis; Male; Mercaptopurine; Methyltransferases; Middle Aged; Phenotype; Prednisone; Thioguanine

Tioguanine (thioguanine) has been proposed as a rescue thiopurine for azathioprine or mercaptopurine intolerant inflammatory bowel disease patients. The use of tioguanine leads to high 6-tioguaninenucleotide (6-thioguaninenucleotide) levels in red blood cells but, contra-intuitively, these have yet not been associated with an increased risk of myelotoxicity.. To assess the role of 6-tioguaninenucleotide concentrations in developing myelotoxicity during tioguanine treatment.. Database analysis of 25 patients treated with tioguanine. Clinical findings and laboratory parameters were related to 6-tioguaninenucleotide levels.. One patient developed a myelodepression (21 mg TG/day for 3 months and 6-tioguaninenucleotide 714 pmol/8 x 10(8) red blood cells). 6-Tioguaninenucleotide levels varied greatly between individuals (mean 6-tioguaninenucleotide level 621 pmol/8 x 10(8) red blood cells, s.d. 340 pmol/8 x 10(8) red blood cells and range 34-1653 pmol/8 x 10(8) red blood cells). The TG dosages (mean 20.6 mg/day and median 20 mg/day) did not correlate with 6-tioguaninenucleotide levels (r = 0.31, N.S.). High 6-tioguaninenucleotide levels (>450 pmol/8 x 10(8) red blood cells) did not effect haemoglobin concentrations (mean 8 mmol/L), peripheral leucocyte (mean 7.5 x 10(9)/L) or platelet counts (mean 298 x 10(9)/L). No correlations were established between laboratory parameters, type of disease and 6-tioguaninenucleotide level.. High 6-tioguaninenucleotide levels in erythrocytes (>450 pmol/8 x 10(8)) during TG treatment compared to azathioprine or mercaptopurine treatment are not indicative for (developing) myelotoxicity.

Topics: Adult; Antimetabolites, Antineoplastic; Bone Marrow Diseases; Celiac Disease; Colitis, Ulcerative; Crohn Disease; Female; Hepatitis, Autoimmune; Humans; Male; Thioguanine

Patients with post-transplant immune-mediated hepatitis (IMH) and recurrent autoimmune hepatitis (RAIH) have a poor outcome and a higher need for retransplantation. Azathioprine (AZA) is used as adjunctive immunosuppression after transplantation; optimizing its dose may be a key point in preserving graft function. Complications of high AZA dosing make dose escalation potentially problematic. Our aim was to correlate AZA metabolite levels with therapeutic effects, toxicity, and adherence to medication in children with IMH and RAIH. Charts of 14 patients were retrospectively reviewed. The post-transplant diagnosis was based on liver biopsy and autoimmune markers. AZA was prescribed after establishing the post-transplant diagnosis. AZA was started at 1.1 (1.0-1.8) mg/kg/day. Routine biochemical studies, tacrolimus levels, 6-thioguanine (6-TG) and 6-methylmercaptopurine levels were assessed every 8 wk. AZA dose was routinely adjusted to achieve 6-TG levels between 235 and 450 pmol per 8 x 10(8) RBC. A total of 92 samples from 14 patients were reviewed. Four patients were excluded because of non-adherence. AZA dose was increased by 245% resulting in eight of 10 patients in the target range; no hepatic or bone marrow toxicity was observed. ALT levels and steroid requirements were significantly reduced (p < 0.05). The AZA dose required to achieve target 6-TG levels was significantly greater in children <10 yr. AZA metabolite testing in children post-liver transplant is useful in assessing adherence to medication and it is potentially helpful in optimizing medication dosing. In younger children the AZA dose requirements were two to four times higher than previously reported standard doses.

Topics: Adolescent; Azathioprine; Child; Female; Hepatitis, Autoimmune; Humans; Immunosuppressive Agents; Kidney Transplantation; Male; Monitoring, Physiologic; Recurrence; Retrospective Studies; Tacrolimus; Thioguanine

Thiopurine drugs are commonly used immunosuppressants in the treatment of inflammatory bowel disease (IBD) as well as in autoimmune hepatitis (AIH), rheumatic diseases and in transplantation medicine. The relatively narrow therapeutic range requires useful therapy control. Therefore, the purpose of this study was to further investigate the rationale and usefulness of therapeutic drug monitoring in the surveillance of thiopurine drug therapy in Crohn's disease, ulcerative colitis and autoimmune hepatitis.. 6-Thioguanine nucleotide (TGN) and 6-methylmercaptopurine nucleotide (MMPN) levels were measured in 182 IBD patients and 18 AIH patients using HPLC-UV.. In our cohort of IBD patients, 18% had TGN levels < 235 pmol/8 x 10 red blood cells (RBC) (recommended range, 235-450 pmol/8 x 10 RBC), 41% of these patients were sent for drug failure. Twenty-four per cent of the IBD patients had TGN levels > 450 pmol/8 x 10 RBC, but only 27% of these experienced adverse effects. Fifty-nine per cent of the patients having drug failure had TGN levels in the recommended range and could therefore be classified as non-responders. In the AIH cohort 33% of the patients had TGN levels below the recommended range but showed clinical response to therapy. MMPN levels increased with the duration of treatment and could be useful for controlling compliance. There was 8.8% of IBD patients who were heterozygous for non-functional TPMT alleles.. TGN monitoring did not identify significant differences between patient groups but allowed the identification of non-responders from non-compliant patients and allowed the differentiation of mild side effects, such as malaise, from genuine toxicity caused by highly increased TGN levels.

Topics: Adolescent; Adult; Aged; Child; Child, Preschool; Chromatography, High Pressure Liquid; Cohort Studies; Colitis, Ulcerative; Crohn Disease; Drug Monitoring; Female; Guanine Nucleotides; Hepatitis, Autoimmune; Heterozygote; Humans; Immunosuppressive Agents; Inflammatory Bowel Diseases; Male; Mercaptopurine; Middle Aged; Purines; Thioguanine; Thionucleotides

Potential adverse effects of azathioprine (AZA), such as neutropenia and hepatotoxicity, make its use in autoimmune hepatitis (AIH) problematic.. To determine longitudinal AZA metabolite levels in a cohort of children with AIH, correlate them with therapeutic effects, medication-induced toxicity and adherence.. From January 2000 to January 2002, 122 blood samples from 30 pediatric patients with AIH were prospectively analyzed. Ten patients had previously been treated with AZA (mean dose of 1.3mg/kg/day) for an average of 30 months. At the outset, 24 patients were taking steroids and 10 had cirrhosis/hypersplenism. Routine biochemical studies, 6-thioguanine (6-TG) and 6-methylmercaptopurine (6-MMP) levels were assessed every 8 weeks. Red blood cell thiopurine methyltransferase (TPMT) enzyme activity was determined in each patient. AZA dose was adjusted to achieve a target 6-TG level 235-450 pmoles per 8 x 10 RBC.. 8/10 patients who had previously been treated with standard doses of AZA had 6-TG below target levels. Increasing AZA mean dose by 50% in those patients resulted in 6/10 patients in target range; ALT levels and steroid requirements were reduced. AZA dosing was safely increased in patients with cirrhosis/hypersplenism. In spite of normal TPMT levels, 64% of patients did not make measurable concentrations of 6-MMP. Inappropriately low 6-TG levels revealed non-adherence in 5 patients. Two patients were identified with AZA hepatotoxicity.. AZA metabolite testing in children with AIH is useful in identifying medication toxicity and non-adherence. AZA dose escalation is safe and may be required in order to achieve 6-TG target levels described for inflammatory bowel disease.

Topics: Adolescent; Adult; Azathioprine; Child; Child, Preschool; Cohort Studies; Female; Hepatitis, Autoimmune; Humans; Immunosuppressive Agents; Longitudinal Studies; Male; Prospective Studies; Steroids; Thioguanine