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Lin R, Lin W, Wang C, Dong J, Zheng W, Zeng D, Liu Y, Lin C, Jiao Z, Huang P. Population pharmacokinetics of azathioprine active metabolite in patients with inflammatory bowel disease and dosage regimens optimisation. Basic Clin Pharmacol Toxicol 2020; 128:482-492. [PMID: 33150655 DOI: 10.1111/bcpt.13530] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 10/12/2020] [Accepted: 11/02/2020] [Indexed: 12/25/2022]
Abstract
Azathioprine is a first-line drug used to maintain the remission of inflammatory bowel disease (IBD). As a prodrug, azathioprine is metabolised to produce active 6-thioguanine nucleotides (6-TGN). There are large individual variations in the pharmacokinetics/pharmacodynamics of 6-TGN in patients with IBD. Here, we aimed to develop a model to quantitatively investigate factors that affect 6-TGN pharmacokinetics to formulate a dosage guideline for azathioprine. Data were collected prospectively from 100 adult patients with IBD who were receiving azathioprine. Patients were genotyped for two single-nucleotide polymorphisms (TPMT*3C c.719A > G and NUDT15 c.415C > T). Using high-performance liquid chromatography, we measured 156 steady-state trough concentrations of 6-TGN within the range 0.09 to 1.16 mg/L (ie 133-1733 pmol per 8 × 108 RBC). The covariates analysed included sex, age, body-weight, laboratory tests and concomitant medications. A population pharmacokinetic model was established using "non-linear mixed-effects modelling" software and the "first-order conditional estimation method with interaction." Body-weight, TPMT*3C polymorphisms and co-therapy with mesalazine were found to be important factors influencing the clearance of 6-TGN. A dosage guideline for azathioprine was developed based on the PPK model that enables individualised azathioprine dosing in adult patients with different body-weights, TPMT*3C genotypes and co-administration with mesalazine.
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Affiliation(s)
- Rongfang Lin
- Department of Pharmacy, The First Affiliated Hospital, Fujian Medical University, Fuzhou, China
| | - Weiwei Lin
- Department of Pharmacy, The First Affiliated Hospital, Fujian Medical University, Fuzhou, China
| | - Changlian Wang
- Department of Pharmacy, The First Affiliated Hospital, Fujian Medical University, Fuzhou, China
| | - Jiashan Dong
- Department of Pharmacy, The First Affiliated Hospital, Fujian Medical University, Fuzhou, China
| | - Weiwei Zheng
- Department of Gastroenterology, The First Affiliated Hospital, Fujian Medical University, Fuzhou, China
| | - Dayong Zeng
- Department of Pharmacy, The First Affiliated Hospital, Fujian Medical University, Fuzhou, China
| | - Yiwei Liu
- Department of Pharmacy, The First Affiliated Hospital, Fujian Medical University, Fuzhou, China
| | - Cuihong Lin
- Department of Pharmacy, The First Affiliated Hospital, Fujian Medical University, Fuzhou, China
| | - Zheng Jiao
- Department of Pharmacy, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Pinfang Huang
- Department of Pharmacy, The First Affiliated Hospital, Fujian Medical University, Fuzhou, China
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Daniel LL, Dickson AL, Chung CP. Precision medicine for rheumatologists: lessons from the pharmacogenomics of azathioprine. Clin Rheumatol 2020; 40:65-73. [PMID: 32617765 DOI: 10.1007/s10067-020-05258-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 06/16/2020] [Accepted: 06/22/2020] [Indexed: 12/13/2022]
Abstract
Precision medicine aims to personalize treatment for both effectiveness and safety. As a critical component of this emerging initiative, pharmacogenomics seeks to guide drug treatment based on genetics. In this review article, we give an overview of pharmacogenomics in the setting of an immunosuppressant frequently prescribed by rheumatologists, azathioprine. Azathioprine has a narrow therapeutic index and a high risk of adverse events. By applying candidate gene analysis and unbiased approaches, researchers have identified multiple variants associated with an increased risk for adverse events associated with azathioprine, particularly bone marrow suppression. Variants in two genes, TPMT and NUDT15, are widely recognized, leading drug regulatory agencies and professional organizations to adopt recommendations for testing before initiation of azathioprine therapy. As more gene-drug interactions are discovered, our field will continue to face the challenge of balancing benefits and costs associated with genetic testing. However, novel approaches in genomics and the integration of clinical and genetic factors into risk scores offer unprecedented opportunities for the application of pharmacogenomics in routine practice. Key Points • Pharmacogenomics can help us understand how individuals' genetics may impact their response to medications. • Azathioprine is a success story for the clinical implementation of pharmacogenomics, particularly the effects of TPMT and NUDT15 variants on myelosuppression. • As our knowledge advances, testing and dosing recommendations will continue to evolve, with our field striving to balance costs and benefits to patients. • As we aim toward the goals of precision medicine, future research may integrate increasingly individualized traits-including clinical and genetic characteristics-to predict the safety and efficacy of particular medications for individual patients.
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Affiliation(s)
- Laura L Daniel
- Department of Medicine, Division of Rheumatology, Vanderbilt University Medical Center (LLD, ALD, CPC), Nashville, TN, 37232, USA
| | - Alyson L Dickson
- Department of Medicine, Division of Rheumatology, Vanderbilt University Medical Center (LLD, ALD, CPC), Nashville, TN, 37232, USA
| | - Cecilia P Chung
- Department of Medicine, Division of Rheumatology, Vanderbilt University Medical Center (LLD, ALD, CPC), Nashville, TN, 37232, USA. .,Tennessee Valley Healthcare System-Nashville Campus (CPC), Nashville, TN, USA. .,Vanderbilt Genetics Institute, Vanderbilt University School of Medicine (CPC), Nashville, TN, USA.
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Combining clinical and candidate gene data into a risk score for azathioprine-associated leukopenia in routine clinical practice. THE PHARMACOGENOMICS JOURNAL 2020; 20:736-745. [PMID: 32054992 PMCID: PMC7426242 DOI: 10.1038/s41397-020-0163-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 01/22/2020] [Accepted: 01/30/2020] [Indexed: 02/06/2023]
Abstract
Leukopenia is a serious, frequent side effect associated with azathioprine use. Currently, we use thiopurine methyltransferase (TPMT) testing to predict leukopenia in patients taking azathioprine. We hypothesized that a risk score incorporating additional clinical and genetic variables would improve the prediction of azathioprine-associated leukopenia. In the discovery phase, we developed four risk score models: (1) age, sex, and TPMT metabolizer status; (2) model 1 plus additional clinical variables; (3) sixty candidate single nucleotide polymorphisms; and (4) model 2 plus model 3. The area under the receiver-operating-characteristic curve (AUC) of the risk scores was 0.59 (95%CI: 0.54-0.64), 0.75 (0.71-0.80), 0.66 (0.61-0.71), and 0.78 (0.74-0.82) for models one, two, three and four, respectively. During the replication phase, models two and four (AUC=0.64, 95%CI: 0.59-0.70 and AUC=0.63, 95%CI: 0.58-0.69, respectively) were significant in an independent group. Compared to TPMT testing alone, additional genetic and clinical variables improve the prediction of azathioprine-associated leukopenia.
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Feng R, Guo J, Zhang SH, Qiu Y, Chen BL, He Y, Zeng ZR, Ben-Horin S, Chen MH, Mao R. Low 6-thioguanine nucleotide level: Effective in maintaining remission in Chinese patients with Crohn's disease. J Gastroenterol Hepatol 2019; 34:679-685. [PMID: 30175864 DOI: 10.1111/jgh.14465] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 08/17/2018] [Accepted: 08/27/2018] [Indexed: 12/13/2022]
Abstract
BACKGROUND AND AIM Measuring 6-thioguanine nucleotide (6-TGN) level is useful in optimizing dose of azathioprine (AZA) and monitoring for toxicity. Lower dose of AZA was suggested for maintenance of clinical remission in Asian patients than Caucasian patients with Crohn's disease (CD). However, the optimal 6-TGN threshold required in Asian patients is undetermined. Therefore, the aim of the current study is to explore the optimal 6-TGN threshold required in Asian patients with CD for maintenance of clinical remission. METHODS A retrospective cohort study in a tertiary referral center recruited 252 CD patients. The primary endpoint was disease relapse. The levels of 6-TGN and AZA dose were compared in remission group and relapse group. Remission rate was compared across the increased 6-TGN level and dose range. RESULTS Patients with 6-TGN range of 0-180.94 pmol/8 × 108 red blood cells (RBC) had lower remission rate compared with those with 180.94-255.50 pmol/8 × 108 RBC (P = 0.020). Quartile analysis showed that increasing 6-TGN level beyond 180 pmol/8 × 108 RBC produced negligible gain in rate of remission. Frequency of adverse events significantly increased in patients with 6-TGN level > 355 pmol/8 × 108 RBC (8.0% with 6-TGN > 355 pmol/8 × 108 RBC vs 2.7% with 6-TGN < 355 pmol/8 × 108 RBC, P = 0.035). CONCLUSION Our study suggested that optimal 6-TGN threshold required to maintain clinical remission in Chinese patients was 180-355 pmol/8 × 108 RBC.
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Affiliation(s)
- Rui Feng
- Department of Gastroenterology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Jing Guo
- Department of Gastroenterology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Sheng-Hong Zhang
- Department of Gastroenterology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Yun Qiu
- Department of Gastroenterology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Bai-Li Chen
- Department of Gastroenterology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Yao He
- Department of Gastroenterology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Zhi-Rong Zeng
- Department of Gastroenterology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Shomron Ben-Horin
- Department of Gastroenterology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China.,Department of Gastroenterology, Sheba Medical Center, Tel Hashomer, Israel
| | - Min-Hu Chen
- Department of Gastroenterology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Ren Mao
- Department of Gastroenterology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
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Ahmad H, Kumar VL. Pharmacotherapy of ulcerative colitis - current status and emerging trends. J Basic Clin Physiol Pharmacol 2019; 29:581-592. [PMID: 30089097 DOI: 10.1515/jbcpp-2016-0014] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Accepted: 05/04/2018] [Indexed: 12/23/2022]
Abstract
Ulcerative colitis (UC) is a chronic mucosal inflammation of the large intestine restricted to the rectum and colon. Its clinical course follows an intermittent pattern with episodes of relapse, followed by remission and eventually resulting in mucosal damage. Although there is no permanent cure for UC, the currently available pharmacotherapy aims to induce and maintain clinical remission, promote the healing of colonic mucosa and avert any surgical intervention. The conventional drug therapy comprising of 5-aminosalicylates, thiopurines and corticosteroids has advanced recently in terms of formulations and dosing schedule, resulting in improved efficacy, safety and compliance. Calcineurin inhibitors, such as cyclosporin and tacrolimus, have emerged as steroid sparing agents. The treatment paradigm of UC patients who are refractory to conventional drugs has changed in view of the availability of biologics. Currently, there are four biologics approved by the US FDA for the treatment of UC, namely, infliximab, adalimumab, golimumab and vedolizumab, and several others are undergoing clinical trial. In this comprehensive review, the advantages and limitations of the medical therapy of UC are elaborated with an emphasis on the pharmacokinetic and pharmacodynamic aspects of the drugs.
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Affiliation(s)
- Hilal Ahmad
- Department of Pharmacology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
| | - Vijay L Kumar
- Department of Pharmacology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
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Multicentric Case-Control Study on Azathioprine Dose and Pharmacokinetics in Early-onset Pediatric Inflammatory Bowel Disease. Inflamm Bowel Dis 2017; 23:628-634. [PMID: 28296824 DOI: 10.1097/mib.0000000000001051] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
BACKGROUND Early-onset inflammatory bowel disease (IBD) is generally aggressive, with a high probability of complications and need of surgery. Despite the introduction of highly effective biological drugs, treatment with azathioprine continues to be important even for early-onset IBD; however, in these patients azathioprine response seems to be reduced. This study evaluated azathioprine doses, metabolite concentrations, and their associations with patients' age in children with IBD treated at 6 tertiary pediatric referral centers. METHODS Azathioprine doses, metabolites, and clinical effects were assessed after at least 3 months of therapy in 17 early-onset (age < 6 yr, cases) and 51 nonearly-onset (aged > 12 and <18 yrs, controls) patients with IBD. Azathioprine dose was titrated on therapeutic efficacy (response and adverse effects). Azathioprine metabolites and thiopurine methyltransferase activity were determined by high-performance liquid chromatography with ultra violet-vis detection (HPLC-UV) methods. RESULTS Frequency of patients in remission was similar among early-onset and control groups, respectively (82% and 84%, P value = 0.72). Early-onset patients required higher doses of azathioprine (median 2.7 versus 2.0 mg·kg·d, P value = 1.1 × 10). Different doses resulted in comparable azathioprine active thioguanine nucleotide metabolite concentrations (median 263 versus 366 pmol/8 × 10 erythrocytes, P value = 0.41) and methylmercaptopurine nucleotide concentrations (median 1455 versus 1532 pmol/8 × 10 erythrocytes, P value = 0.60). Lower ratios between thioguanine nucleotide metabolites and azathioprine doses were found in early-onset patients (median 98 versus 184 pmol/8 × 10 erythrocytes·mg·kg·d, P value = 0.017). Interestingly, early-onset patients presented also higher thiopurine methyltransferase activity (median 476 versus 350 nmol methylmercaptopurine/mg hemoglobin/h, P-value = 0.046). CONCLUSIONS This study demonstrated that patients with early-onset IBD present increased inactivating azathioprine metabolism, likely because of elevated activity of the enzyme thiopurine methyltransferase.
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Liu H, Ding L, Zhang F, Zhang Y, Gao X, Hu P, Bi H, Huang M. The impact of glutathione S–transferase genotype and phenotype on the adverse drug reactions to azathioprine in patients with inflammatory bowel diseases. J Pharmacol Sci 2015; 129:95-100. [DOI: 10.1016/j.jphs.2015.02.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Revised: 02/02/2015] [Accepted: 02/24/2015] [Indexed: 01/26/2023] Open
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Roberts RL, Barclay ML. Update on thiopurine pharmacogenetics in inflammatory bowel disease. Pharmacogenomics 2015; 16:891-903. [PMID: 26067482 DOI: 10.2217/pgs.15.29] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Azathioprine and 6-mercaptopurine remain pivotal therapies for the maintenance of disease remission in patients with Crohn's disease and ulcerative colitis. While thiopurine S-methyltransferase deficiency was the first pharmacogenetic phenomenon to be recognized to influence thiopurine toxicity and reliably predict leukopenia, it does not predict other adverse effects, nor does it explain most cases of thiopurine resistance. In recent years, a number of other genetic polymorphisms have received increasing attention in the literature. In particular, SNPs in NUDT15 and in the class II HLA locus have been shown to predict thiopurine-related leukopenia and pancreatitis. The aim of this review is to provide a concise update of genetic variability which may influence patient response to azathioprine and 6-mercaptopurine.
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Affiliation(s)
- Rebecca L Roberts
- Department of Surgical Sciences, Dunedin School of Medicine, PO Box 56, Dunedin, New Zealand
| | - Murray L Barclay
- Department of Medicine, University of Otago Christchurch, PO Box 4345, Christchurch, New Zealand.,Department of Gastroenterology, Christchurch Hospital, Private Bag 4710, Christchurch, New Zealand
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