BACKGROUND: The additional value of azathioprine concomitant treatment on infliximab pharmacokinetics in children is not well described yet. AIMS: In the present study, we aimed to describe the relationship between thiopurine metabolite levels, infliximab trough levels, anti-IFX antibody formation, and clinical and laboratory markers of disease activity in pediatric patients with Crohn's disease, and to assess non-adherence. METHODS: Data were collected prospectively during repeated visits from pediatric patients followed for Crohn's disease in two Czech pediatric inflammatory bowel disease centers between January 2016 and June 2017. Thiopurine metabolites (6-thioguanine and 6-methylmercaptopurine) were measured by high-performance liquid chromatography. Infliximab trough levels and anti-IFX antibody serum levels were measured routinely by ELISA. The risk of loss of response to infliximab therapy was also assessed. RESULTS: A significant association between infliximab serum levels and 6-thioguanine erythrocyte levels was observed when tested as categorical variables (63 patients, 321 observations). To predict infliximab levels > 5 µg/mL, we propose a 6-thioguanine cutoff of 278 pmol/8 × 108 erythrocytes (sensitivity, 0.799; specificity, 0.347). A higher loss-of-response-to-infliximab rate (tested in a subgroup of 51 patients) was observed in patients with undetectable 6-thioguanine levels than in those with detectable levels (p = 0.026). Non-adherence to azathioprine therapy was suspected in 20% of patients. CONCLUSION: Thiopurine metabolite monitoring in pediatric patients with Crohn's disease is useful when optimizing combination therapy. Pediatric patients with undetectable 6-thioguanine levels are more likely to lose response to infliximab therapy. When targeting optimal infliximab levels, the 6-thioguanine cutoff levels in children appear to be higher than in adults.

• MeSH
• azathioprin terapeutické užití   MeSH
• biologické markery MeSH
• Crohnova nemoc farmakoterapie   MeSH
• dítě MeSH
• imunologické faktory terapeutické užití   MeSH
• infliximab terapeutické užití   MeSH
• kombinovaná farmakoterapie MeSH
• lidé MeSH
• longitudinální studie MeSH
• merkaptopurin analogy a deriváty   analýza   MeSH
• mladiství MeSH
• prospektivní studie MeSH
• Check Tag
• dítě MeSH
• lidé MeSH
• mladiství MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• multicentrická studie MeSH
• pozorovací studie MeSH
• Názvy látek
• 6-methylthiopurine MeSH Prohlížeč
• azathioprin MeSH
• biologické markery MeSH
• imunologické faktory MeSH
• infliximab MeSH
• merkaptopurin MeSH

BACKGROUND: Approximately 10-28 % of patients experience adverse drug reactions related to treatment with thiopurines. The most serious reaction is myelosuppression, typically manifested as leucopenia, which occurs in approximately 2-5 % of patients. Other adverse drug reactions that often accompany thiopurine therapy are pancreatitis, hepatotoxicity, allergic reactions, digestive intolerance, arthralgia, febrile conditions, and rash. OBJECTIVE: The objective of this study was to assess the relationship between variant alleles of thiopurine S-methyltransferase (SNPs 238G > C, 460G > A and 719A > G), inosine triphosphate diphosphatase (SNPs 94C > A and IVS2 + 21A > C), and xanthine dehydrogenase (837C > T) and the occurrence of adverse drug reactions to azathioprine therapy. METHODS: Genotype was determined for 188 Caucasians diagnosed with inflammatory bowel disease treated with a standard dose of azathioprine (1.4-2.0 mg/kg/day). Allelic variants were determined by PCR-REA and real-time PCR methods. Results were statistically evaluated by use of Fisher's test and by odds ratio calculation. RESULTS: Variant genotype thiopurine S-methyltransferase predisposes to development of leucopenia (P = 0.003, OR = 5, CI 95 %, 1.8058-13.8444). Although not statistically significant, we observed a trend that suggested correlation between the occurrence of digestive intolerance and the variant genotype inosine triphosphate diphosphatase (P = 0.1102; OR 15.63, CI 95 %, 1.162-210.1094), and between the occurrence of pancreatitis and the variant allele xanthine dehydrogenase 837T (P = 0.1124; OR 12,1, CI 95 %, 1.15-126.37). CONCLUSION: The variant genotype thiopurine S-methyltransferase has been associated with the occurrence of leucopenia. The involvement of polymorphisms in inosine triphosphate diphosphatase and xanthine dehydrogenase genes in the development of digestive intolerance and pancreatitis will require further verification.

• MeSH
• azathioprin škodlivé účinky   terapeutické užití   MeSH
• gastrointestinální nemoci chemicky indukované   genetika   MeSH
• genetická predispozice k nemoci MeSH
• genotyp MeSH
• idiopatické střevní záněty farmakoterapie   MeSH
• imunosupresiva škodlivé účinky   terapeutické užití   MeSH
• leukopenie chemicky indukované   genetika   MeSH
• lidé MeSH
• methyltransferasy genetika   metabolismus   MeSH
• pankreatitida chemicky indukované   genetika   MeSH
• polymerázová řetězová reakce metody   MeSH
• polymorfismus genetický * MeSH
• prohibitiny MeSH
• regulace genové exprese MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• azathioprin MeSH
• imunosupresiva MeSH
• methyltransferasy MeSH
• PHB2 protein, human MeSH Prohlížeč
• prohibitiny MeSH
• thiopurine methyltransferase MeSH Prohlížeč