N-acetyltransferase 2 Genotype Research Articles

Pharmacogenetic variability of tuberculosis biomarkers in native and mestizo Peruvian populations.

In Peru, 29 292 people were diagnosed with tuberculosis in 2022. Although tuberculosis treatments are effective, 3.4%-13% are associated with significant adverse drug reactions, with drug-induced liver injury (DILI) considered the most predominant. Among the first-line antituberculosis drugs, isoniazid is the main drug responsible for the appearance of DILI. In liver, isoniazid (INH) is metabolized by N-acetyltransferase-2 (NAT2) and cytochrome P450 2E1 (CYP2E1). Limited information exists on genetic risk factors associated with the presence of DILI to antituberculosis drugs in Latin America, and even less is known about these factors in the native and mestizo Peruvian population. The aim of this study was to determine the prevalence of NAT2 and CYP2E1 genotypes in native and mestizo population. An analytical cross-sectional analysis was performed using genetic data from mestizo population in Lima and native participants from south of Peru. NAT2 metabolizer was determined as fast, intermediate and slow, and CYP2E1 genotypes were classified as c1/c1, c1/c2 and c2/c2, from molecular tests and bioinformatic analyses. Of the 472 participants, 36 and 6 NAT2 haplotypes were identified in the mestizo and native population, respectively. In mestizo population, the most frequent NAT2*5B and NAT2*7B haplotypes were associated with DILI risk; while in natives, NAT2*5G and NAT2*13A haplotypes were associated with decreased risk of DILI. For CYP2E1, c1/c1 and c1/c2 genotypes are the most frequent in natives and mestizos, respectively. The linkage disequilibrium of NAT2 single nucleotide polymorphisms (SNPs) was estimated, detecting a block between all SNPs natives. In addition, a block between rs1801280 and rs1799929 for NAT2 was detected in mestizos. Despite the limitations of a secondary study, it was possible to report associations between NAT2 and CYP2E alleles with Peruvian native and mestizo by prevalence ratios. The results of this study will help the development of new therapeutic strategies for a Tuberculosis efficient control between populations.

Influence of N-acetyltransferase 2 polymorphisms and clinical variables on liver function profile of tuberculosis patients

ABSTRACT Background Single nucleotide polymorphisms (SNPs) in the N-acetyltransferase 2 (NAT2) gene as well as several other clinical factors can contribute to the elevation of liver function test values in tuberculosis (TB) patients receiving antitubercular therapy (ATT). Research design and methods A prospective study involving dynamic monitoring of the liver function tests among 130 TB patients from baseline to 98 days post ATT initiation was undertaken to assess the influence of pharmacogenomic and clinical variables on the elevation of liver function test values. Genomic DNA was extracted from serum samples for the assessment of NAT2 SNPs. Further, within this study population, we conducted a case control study to identify the odds of developing ATT-induced drug-induced liver injury (DILI) based on NAT2 SNPs, genotype and phenotype, and clinical variables. Results NAT2 slow acetylators had higher mean [90%CI] liver function test values for 8–28 days post ATT and higher odds of developing DILI (OR: 2.73, 90%CI: 1.05–7.09) than intermediate acetylators/rapid acetylators. Conclusion The current study findings provide evidence for closer monitoring among TB patients with specific NAT2 SNPs, genotype and phenotype, and clinical variables, particularly between the period of more than a week to one-month post ATT initiation for better treatment outcomes.

Isoniazid-induced liver injury risk level in different variants of N-acetyltransferase 2 (NAT2) polymorphisms: A literature review

Individual NAT2 genotype identity data should be enriched to prevent Isoniazid-induced liver injury (IDILI) and optimize the dose of Isoniazid (INH). Therefore, this study aims to present the level of IDILI risk for specific genotype alleles. The data collection involves literature indexed by Google Scholar, Scopus, and Pubmed databases. The search uses a combination of the following keyword variants “INH” OR “INH”, “liver injury” OR “hepatotoxicity”, “polymorphism” OR “pharmacogenomic”, and “N-acetyltransferase 2” OR “NAT2”. Furthermore, the screening results of library sources were narrowed to 11 original articles that met the inclusion criteria. The IDILI risk assessment analysis due to NAT2 enzyme polymorphism following the odds ratio has a 95% confidence interval. The results showed that the IDILI risk level of the slow acetylator group was 3.11 times higher than other populations. Meanwhile, the rapid and intermediate acetylator groups were not at risk. Three variants related to *6 allele were classified as high risk; *6A/*6A risk 5.76 times, *6A/*7B (5.54 times), and *6/*7 (4 times). The three allele configurations of the *5 and *7 were also classified as a risk; *5B/*7B (5 times), *7B/*7B (3.23 times), and *5/*7 (2,74 times).

Association of Cytochrome P450 2E1 and N-Acetyltransferase 2 Genotypes with Serum Isoniazid Level and Anti-Tuberculosis Drug-Induced Hepatotoxicity: A Cross-Sectional Study.

Anti-tuberculosis drug-induced hepatotoxicity can result from genetic polymorphism of the isoniazid (INH) metabolizing enzyme. This study aimed to determine the effect of genetic polymorphism of N-acetyltransferase 2 (NAT2) and cytochrome P450 2E1 (CYP2E1) genes on serum isoniazid level and drug-induced hepatotoxicity. A cross-sectional study was conducted on 120 patients (with and without hepatotoxicity) with pulmonary tuberculosis from June 2019 to April 2022 in Tehran (Iran). High-performance liquid chromatography was used to measure the serum concentration of INH and acetylisoniazid (AcINH). NAT2 and CYP2E1 genotypes were determined using polymerase chain reaction and restriction fragment length polymorphism methods. Data were analyzed using SPSS software (version 22.0) with independent two-sample t test, Chi square test, or Fisher's exact test. P<0.05 was considered statistically significant. A total of 40 patients showed hepatotoxicity. The risk of anti-tuberculosis drug-induced hepatotoxicity was significantly higher in patients who are slow acetylator (SA) phenotype than in rapid or intermediate acetylator (P<0.001). NAT2*4/*4 genotypes were not found in patients with hepatotoxicity. The frequency of NAT2*5 and NAT2*6 haplotypes and serum INH concentration was significantly higher in patients with hepatotoxicity than in those without (P=0.003, P<0.001, and P<0.001, respectively). NAT2*4 haplotype was correlated with protection against hepatotoxicity. A combination of SA and CYP2E1 C1/C1 genotype was significantly associated with hepatotoxicity (P<0.001). Hepatotoxicity in Iranian patients with tuberculosis was confirmed due to the presence of NAT2 SA polymorphism. Determining NAT2 and CYP2E1 genotypes and/or INH concentration can be a valuable tool to identify patients susceptible to hepatotoxicity.

Correlation of N-acetyltransferase 2 genotype and acetylation status with plasma isoniazid concentration and its metabolic ratio in ethiopian tuberculosis patients

Unfavorable treatment outcomes for tuberculosis (TB) treatment might result from altered plasma exposure to antitubercular drugs in TB patients. The present study investigated the distribution of the N-Acetyltransferase 2 (NAT2) genotype, isoniazid acetylation status, genotype–phenotype concordance of NAT2, and isoniazid plasma exposure among Ethiopian tuberculosis patients. Blood samples were collected from newly diagnosed TB patients receiving a fixed dose combination of first-line antitubercular drugs daily. Genotyping of NAT2 was done using TaqMan drug metabolism assay. Isoniazid and its metabolite concentration were determined using validated liquid chromatography-tandem mass spectrometry (LC–MS/MS). A total of 120 patients (63 male and 57 female) were enrolled in this study. The mean daily dose of isoniazid was 4.71 mg/kg. The frequency of slow, intermediate, and fast NAT2 acetylators genotypes were 74.2%, 22.4%, and 3.3% respectively. The overall median isoniazid maximum plasma concentration (Cmax) was 4.77 µg/mL and the AUC0–7 h was 11.21 µg.h/mL. The median Cmax in slow, intermediate, and fast acetylators were 5.65, 3.44, and 2.47 μg/mL, respectively. The median AUC0–7 h hour in slow, intermediate, and fast acetylators were 13.1, 6.086, and 3.73 mg•h/L, respectively. The majority (87.5%) of the study participants achieved isoniazid Cmax of above 3 µg/mL, which is considered a lower limit for a favorable treatment outcome. There is 85% concordance between the NAT2 genotype and acetylation phenotypes. NAT2 genotype, female sex, and dose were independent predictors of Cmax and AUC0–7 h (p < 0.001). Our finding revealed that there is a high frequency of slow NAT2 genotypes. The plasma Cmax of isoniazid was higher in the female and slow acetylators genotype group. The overall target plasma isoniazid concentrations in Ethiopian tuberculosis patients were achieved in the majority of the patients. Therefore, it is important to monitor adverse drug reactions and the use of a higher dose of isoniazid should be closely monitored.

Effect of N-acetyltransferase 2 genetic polymorphism on 4,4'-methylenebis(2-chloroaniline)-induced genotoxicity and oxidative stress.

4,4'-Methylenebis(2-chloroaniline) or MOCA is an aromatic amine used primarily in polyurethane and rubber industry. MOCA has been linked to hepatomas in animal studies while limited epidemiologic studies reported the association of exposure to MOCA and urinary bladder and breast cancer. We investigated MOCA-induced genotoxicity and oxidative stress in DNA repair-deficient Chinese hamster ovary (CHO) cells stably transfected with human metabolizing enzymes CYP1A2 and N-acetyltransferase 2 (NAT2) variants as well as in rapid, intermediate, and slow NAT2 acetylator cryopreserved human hepatocytes. N-acetylation of MOCA was highest in UV5/1A2/NAT2*4 followed by UV5/1A2/NAT2*7B and UV5/1A2/NAT2*5B CHO cells. Human hepatocytes showed a NAT2 genotype-dependent response with highest N-acetylation in rapid acetylators followed by intermediate and slow acetylators. MOCA induced higher levels of mutagenesis and DNA damage in UV5/1A2/NAT2*7B compared to UV5/1A2/NAT2*4 and UV5/1A2/NAT2*5B cells (p < 0.0001). MOCA also induced higher levels of oxidative stress in UV5/1A2/NAT2*7B cells. MOCA caused concentration-dependent increase in DNA damage in cryopreserved human hepatocytes (linear trend p < 0.001) which was NAT2 genotype dependent i.e., highest in rapid acetylators, lower in intermediate acetylators, and lowest in slow acetylators (p < 0.0001). Our findings show that N-acetylation and genotoxicity of MOCA is NAT2 genotype dependent and suggest that individuals possessing NAT2*7B are at higher risk to MOCA-induced mutagenicity. DNA damage, and oxidative stress. They confirm significant differences in genotoxicity between the NAT2*5B and NAT2*7B alleles, both of which are associated with slow acetylator phenotype.

Systematic-review-of-population-pharmacokinetic-models-of-isoniazid-in-children-and-adults-with-tuberculosis

Introduction: Isoniazid (INH) is one of the first-line anti-tuberculosis (anti-TB) drugs that have both bactericidal and bacteriostatic properties depending on the rate of mycobacterial growth. Several population pharmacokinetic (PPK) models of INH were established. This systemic review aims to summarise published PPK parameters of INH in the models and to identify covariates influencing the INH pharmacokinetic parameters of models. Method: A search of publications for PPK analyses of INH in volunteers or TB patients from 2011 to 2021 was conducted in PubMed and Scopus databases. Reviews, methodology articles, non-compartmental analysis, in vitro, and animal studies were excluded. Result: Twelve studies were included in this review. Most of the included studies described the pharmacokinetics of INH as two-compartmental with first-order absorption and elimination in most of the included studies. Eleven studies reported N-acetyltransferase 2 (NAT2) genotype polymorphism as the most common significant covariate affecting the pharmacokinetic parameters of INH. Other common significant covariates reported include body weight (n = 2) and body mass index (BMI) (n = 1). Conclusion: The variability of population clearance parameters of INH was explained mainly by the NAT2 genotype polymorphism. This indicates that to optimise and rationalise the dosing regimen of INH, a patient’s NAT2 genotype should be considered. At the same time, body weight and BMI values should be considered when making dosing adjustments for INH to achieve the therapeutic range.

N-acetyltransferase 2 acetylator genotype-dependent N-acetylation and toxicity of the arylamine carcinogen β-naphthylamine in cryopreserved human hepatocytes.

We used cryopreserved human hepatocytes that express rapid, intermediate, and slow acetylator N-acetyltransferase 2 (NAT2) genotypes to measure the N-acetylation of β-naphthylamine (BNA) which is one of the aromatic amines found in cigarette smoke including E-cigarettes. We investigated the role of NAT2 genetic polymorphism in genotoxicity and oxidative stress induced by BNA. In vitro BNA NAT2 activities in rapid acetylators was 1.6 and 3.5-fold higher than intermediate (p &lt; 0.01) and slow acetylators (p &lt; 0.0001). BNA N-acetylation in situ was 3 to 4- fold higher in rapid acetylators than slow acetylators, following incubation with 10 and 100µM BNA (p &lt; 0.01). DNA damage was two to threefold higher in the rapid versus slow acetylators (p &lt; 0.0001) and 2.5-fold higher in intermediate versus slow acetylators following BNA treatment at 100 and 1000μM, ROS/RNS level was the highest in rapid acetylators followed by intermediate and then slow acetylators (p &lt; 0.0001). Our findings show that theN-acetylation of BNA is NAT2 genotype dependent in cryopreserved human hepatocytes and our data further document an important role for NAT2 genetic polymorphism in modifying BNA-induced genotoxicity and oxidative damage.

The interaction between smoking and bladder cancer genetic variants on urothelial cancer risk by disease aggressiveness.

BackgroundSmoking has shown interactions with bladder cancer (BC) genetic variants, especially N‐acetyltransferase‐2 (NAT2), a tobacco smoke metabolism gene, on BC risk. The interactions by disease aggressiveness are unknown.MethodsWe investigated the interaction between smoking and 18 single nucleotide polymorphisms (SNPs) for BC, individually and in a genetic risk score (GRS), on urothelial cancer (UC) risk including BC. We analysed data from 25,453 individuals with 520 incident UCs during follow‐up, 339 non‐aggressive (non‐fatal, non‐muscle invasive) and 163 aggressive (all other) UCs. Hazard ratios (HRs), absolute risks and additive and multiplicative interactions for two‐by‐two combinations of never/ever smoking with low/high genetic risk were calculated.ResultsSmoking and NAT2 rs1495741 interacted strongly, positively on aggressive UC on both the multiplicative (p = 0.004) and additive (p = 0.0002) scale, which was not observed for non‐aggressive UC (p interactions ≥ 0.6). This manifested in a higher HR of aggressive UC by ever smoking for the slow acetylation NAT2 genotype (HR, 5.00 [95% confidence interval, 2.67–9.38]) than for intermediate/fast acetylation NAT2 (HR, 1.50 [0.83–2.71]), and in differences in absolute risks by smoking and NAT2 genotype. Smoking also interacted additively and positively with the GRS on any UC (p = 0.01) and non‐aggressive UC (p = 0.02), but not on aggressive UC (p = 0.1). Gene‐smoking interactions of lesser magnitude than for NAT2 were found for SNPs in APOBEC3A, SLC14A1 and MYNN.ConclusionsThis study suggests that smoking increases UC risk more than expected when combined with certain genetic risks. Individuals with the slow acetylation NAT2 variant might particularly benefit from smoking intervention to prevent lethal UC; however, replication in larger studies is needed.

[Association between isoniazid induced hepatotoxicity and host N-acetyltransferase 2 polymorphisms].

Isoniazid(INH, H) has been a key drug for treating drug-susceptible tuberculosis (TB) for nearly seventy years. The differences in the pharmacokinetic(PK) might affect INH absorption. Low plasma concentration is related to less treatment outcomes and vice versa, but higher plasma concentrations can induce hepatotoxicity or death. Factors that can cause fluctuations in blood concentration include INH absorption (i.e. drug-drug or drug-food interactions and other diseases such as gastrointestinal problems, diabetes or TB) and abnormal metabolization by the liver. N-acetyltransferase 2 (NAT2) genetic polymorphism significantly affects the plasma concentrations of INH. However, there is a lack of guidelines for the management of adverse drug reactions caused by isoniazid therapy, and the only measures taken to address adverse reactions to isoniazid are abrupt discontinuation of the drug or reduction in the dose of isoniazid based on clinical experience, but such measures could lead to the development of drug resistance in Mycobacterium tuberculosis. Therefore, further clarification of the correlation between the host NAT2 genotype and its phenotypic polymorphisms, plasma isoniazid concentration and adverse effects can help to improve the efficacy and minimize the adverse effects.

Influence of NAT2 Genotype and Maturation on Isoniazid Exposure in Low-Birth-Weight and Preterm Infants With or Without Human Immunodeficiency Virus (HIV) Exposure.

Isoniazid (INH) metabolism depends on the N-acetyl transferase 2 (NAT2) enzyme, whose maturation process remains unknown in low birth weight (LBW) and preterm infants. We aimed to assess INH exposure and safety in infants receiving oral tuberculosis prevention. This population pharmacokinetics (PK) analysis used INH and N-acetyl-isoniazid (ACL) concentrations in infants (BW ≤ 4kg), including preterm, with follow-up for 6 months. PK parameters were described using nonlinear mixed effects modeling. Simulations were performed to assess INH exposure and optimal dosing regimens, using 2 targets: Cmax at 3-6mg/L and area under the curve (AUC) ≥ 10.52mg h/L. We included 57 infants (79% preterm, 84% LBW) in the PK analysis, with a median (range) gestational age of 34 (28.7-39.4) weeks. At the time of sampling, postnatal age was 2.3 (0.2-7.3) months and weight (WT) was 3.7 (0.9-9.3) kg. NAT2 genotype was available in 43 (75.4%) patients (10 slow, 26 intermediate, and 7 fast metabolizers). Ninety percent of NAT2 maturation was attained by 4.4 post-natal months. WT, postmenstrual age, and NAT2 genotype significantly influenced INH exposure, with a 5-fold difference in AUC between slow and fast metabolizers for the same dose. INH appeared safe across the broad range of exposure for 61 infants included in the safety analysis. In LBW/preterm infants, INH dosing needs frequent adjustment to account for growth and maturation. Pharmacogenetics-based dosing regimens is the most powerful approach to deliver safe and equalized exposures for all infants, because NAT2 genotype highly impacts INH pharmacokinetic variability.

Correlation between N-Acetyltransferase 2 (NAT2) Polymorphism Genotype with Plasma Isoniazid (INH) Concentration in MDR TB Patients Receiving Short Regimen in West Sumatera

Background: Isoniazid (INH) is one of the most potent TB drug. High dose INH is used in short regimen MDR TB drugs. The genetic polymorphism of NAT2 affects the acetylation status. Awareness of the patients’ acetylator status is important to determine the risk of toxicity, treatment failure and drug resistance. The aim of this study was to demonstrate NAT2 genotype association with INH plasma concentration after 2 hours of oral INH therapy. Methods: This was a cross sectional study of MDR TB patients who received short term combination therapy at RSUP Dr. M.Djamil Padang, Achmad Muchtar Hospital Bukittinggiand West Sumatra Pulmonary Hospital from September 2019 to February 2020. Patients were examined for NAT2 genotype and plasma INH concentration. The results of the plasma INH concentrations obtained were evaluated based on the NAT2 acetylator phenotype group.Results: The majority of the subjects weremen (62.5%), aged 40-64 years (50%), had the most common comorbid of diabetes mellitus (31.25%), were normoweight (75%) and had negative HIV status (93.8%). A total of 7 alleles consisting of 7 SNPs and 7 variations of the NAT2 genotype were found in MDR TB patients who received short-term therapy. The NAT2*12A alleles (56.25%) was the most common allele and was a fast acetylator. Based on the bimodal distribution, the median concentration of INH in the fast and slow acetylator were 1.25 µg/ml and 5.24 µg/ml, respectively. The median values of INH concentration based on the trimodal distribution for fast, intermediate, and slow acetylators were 1.25 µg/ml, 2.17 µg/ml and 5.24 µg/ml. Conclusion: There were no correlations between the type of NAT2 acetylator phenotype and plasma INH concentrations.

Homozygotes NAT2*5B slow acetylators are highly associated with hepatotoxicity induced by anti-tuberculosis drugs.

BACKGROUND Distinct N-acetyltransferase 2 (NAT2) slow acetylators genotypes have been associated with a higher risk to develop anti-tuberculosis drug-induced hepatotoxicity (DIH). However, studies have not pointed the relevance of different acetylation phenotypes presented by homozygotes and compound heterozygotes slow acetylators on a clinical basis.OBJECTIVES This study aimed to investigate the association between NAT2 genotypes and the risk of developing DIH in Brazilian patients undergoing tuberculosis treatment, focusing on the discrimination of homozygotes and compound heterozygotes slow acetylators.METHODS/FINDINGS The frequency of NAT2 genotypes was analysed by DNA sequencing in 162 patients undergoing tuberculosis therapy. The mutation analyses revealed 15 variants, plus two new NAT2 mutations, that computational simulations predicted to cause structural perturbations in the protein. The multivariate statistical analysis revealed that carriers of NAT2*5/*5 slow acetylator genotype presented a higher risk of developing anti-tuberculosis DIH, on a clinical basis, when compared to the compound heterozygotes presenting NAT2*5 and any other slow acetylator haplotype [aOR 4.97, 95% confidence interval (CI) 1.47-16.82, p = 0.01].CONCLUSION These findings suggest that patients with TB diagnosis who present the NAT2*5B/*5B genotype should be properly identified and more carefully monitored until treatment outcome in order to prevent the occurrence of anti-tuberculosis DIH.

Isoniazid Population Pharmacokinetics and Dose Recommendation for Korean Patients With Tuberculosis Based on Target Attainment Analysis.

The wide variability of isoniazid (INH) pharmacokinetics is mainly attributed to the trimodal N-acetyltransferase 2 (NAT2) acetylator phenotype, that is, rapid, intermediate, and slow. Consequently, a uniform INH dose in current clinical practice may lead to treatment failure and emergence of drug resistance. There is a lack of studies on specific doses of INH for different NAT2 acetylator phenotypes among tuberculosis (TB) patients. Therefore, we aimed to provide insight into the optimal dosing of INH for each NAT2 acetylator phenotype with respect to the probability of achieving a pharmacokinetic (PK)/pharmacodynamic target. PK, the NAT2 genotype, and clinical data were collected in a multicenter prospective cohort study conducted at 13 clinical centers in Korea. Population PK modeling and simulation were carried out. Data from 454 TB patients were divided into a training data set and a test data set at a ratio of 4 to 1. The PK of the training data were best described by a 2-compartment model with allometric scaling for body size effect. Importantly, NAT2 acetylator phenotypes significantly affected the apparent clearance. Our model, which provided better predictive performance compared with previously published models, was evaluated by external validation using the test set. The simulation for assessing target efficacy and toxicity indicated that the best INH dosing regimens for Korean tuberculosis patients were once-daily doses of 400, 300, and 200 mg for rapid, intermediate, and slow acetylators, respectively. In conclusion, our study provides a step forward in precision dosing for antituberculosis management.

Influence of N-acetyltransferase 2 gene polymorphisms on the in vitro metabolism of the epidermal growth factor receptor inhibitor rociletinib.

Rociletinib showed activity in T790M-positive non-small cell lung cancer patients. It undergoes amide hydrolysis to form M502, followed by N-acetylation to M544 or amide hydrolysis to M460. We identified the enzymes responsible for rociletinib metabolism, and investigated the relationship between M544 formation and N-acetyltransferase 2 (NAT2) polymorphisms. Rociletinib and metabolites were incubated with carboxylesterase (CES)1b, CES1c, CES2, NAT1, NAT2, arylacetamide deacetylase, inhibitors, pooled human liver microsomes (HLM) and cytosols (HLC). Cytosols (n =107) were genotyped for NAT2 polymorphisms (rs1041983 and rs1801280) and incubated with M502. Human hepatocytes from intermediate (NAT2*6/*12A) and slow (NAT2*5B/*5B) acetylators were incubated with 10μM rociletinib and metabolites for 24 hours. Metabolites were measured by high-performance liquid chromatography. M502 was formed from rociletinib and M544 by CES2 and HLM; M544 and N-acetyl-M460 were formed by NAT2 and HLC; M460 was not formed by CES or arylacetamide deacetylase. M502 formation by HLM was inhibited by bis-(4-nitrophenyl)phosphate and eserine (10μM). M544 formation in HLC was inhibited by 100 μM quercetin and was associated with NAT2 genotype (P <.0001). M460 formation in HLM was inhibited by eserine, and M460 was N-acetylated in HLC. Hepatocytes formed M502, M544 and M460. The intermediate acetylator showed higher production (range: 3.4-5.1-fold) of N-acetylated metabolites than the slow acetylator. Results indicate that NAT2 and CES2 are involved in rociletinib metabolism, and polymorphic NAT2 could alter drug exposure in patients. Slow NAT2 acetylators would have higher exposure to M502 and M460 and consequently, be at increased risk of experiencing hyperglycaemia and QTc prolongation.

Functional Characterization of the Effects of N-acetyltransferase 2 Alleles on N-acetylation of Eight Drugs and Worldwide Distribution of Substrate-Specific Diversity.

Variability in the enzymatic activity of N-acetyltransferase 2 (NAT2) is an important contributor to interindividual differences in drug responses. However, there is little information on functional differences in N-acetylation activities according to NAT2 phenotypes, i.e., rapid, intermediate, slow, and ultra-slow acetylators, between different substrate drugs. Here, we estimated NAT2 genotypes in 990 Japanese individuals and compared the frequencies of different genotypes with those of different populations. We then calculated in vitro kinetic parameters of four NAT2 alleles (NAT2∗4, ∗5, ∗6, and ∗7) for N-acetylation of aminoglutethimide, diaminodiphenyl sulfone, hydralazine, isoniazid, phenelzine, procaineamide, sulfamethazine (SMZ), and sulfapyrizine. NAT2∗5, ∗6, and ∗7 exhibited significantly reduced N-acetylation activities with lower Vmax and CLint values of all drugs when compared with NAT2∗4. Hierarchical clustering analysis revealed that 10 NAT2 genotypes were categorized into three or four clusters. According to the results of in vitro metabolic experiments using SMZ as a substrate, the frequencies of ultra-slow acetylators were calculated to be 29.05–54.27% in Europeans, Africans, and South East Asians, whereas Japanese and East Asian populations showed lower frequencies (4.75 and 11.11%, respectively). Our findings will be helpful for prediction of responses to drugs primarily metabolized by NAT2.

Association of NAT2 genetic polymorphism with the efficacy of Neurotropin\xae for the enhancement of aggrecan gene expression in nucleus pulposus cells: a pilot study

BackgroundIntervertebral disc degeneration, one of the major causes of low-back pain, results from altered biosynthesis/turnover of extracellular matrix in the disc. Previously, we reported that the analgesic drug Neurotropin® (NTP) had an anabolic effect on glycosaminoglycan synthesis in cultured nucleus pulposus (NP) cells via the stimulation of chondroitin sulfate N-acetylgalactosaminyltransferase 1. However, its effect on the aggrecan core protein was not significantly detected, because of the data variance. A microarray analysis suggested that the effect of NTP on aggrecan was correlated with N-acetyltransferase 2 (NAT2), a drug-metabolizing enzyme. Specific NAT2 alleles are known to correlate with rapid, intermediate, and slow acetylation activities and side effects of various drugs. We investigated the association between the efficacy of NTP on aggrecan expression and the NAT2 genotype in cell donors.MethodsNP cells were isolated from intervertebral disc tissues donated by 31 Japanese patients (28–68 years) who underwent discectomy. NTP was added to the primary cell cultures and its effect on the aggrecan mRNA was analyzed using real-time quantitative PCR. To assess acetylator status, genotyping was performed based on the inferred NAT2 haplotypes of five common single-nucleotide polymorphisms using allele-specific PCR.ResultsThe phenotype frequencies of NAT2 in the patients were 0%, 42.0%, and 58.0% for slow, intermediate, and rapid acetylators, respectively. The proportions of responders to NTP treatment (aggrecan upregulation, ≥ 1.1-fold) in the intermediate and rapid acetylators were 76.9% and 38.9%, respectively. The odds ratio of the comparison of the intermediate acetylator status between responders and nonresponders was 5.2 (95% CI 1.06–26.0, P = 0.036), and regarding the 19 male patients, this was 14.0 (95% CI 1.54–127.2, P = 0.012). In the 12 females, the effect was not correlated with NAT2 phenotype but seemed to become weaker along with aging.ConclusionsAn intermediate acetylator status significantly favored the efficacy of NTP treatment to enhance aggrecan production in NP cells. In males, this tendency was detected with higher significance. This study provides suggestive data of the association between NAT2 variants and the efficacy of NTP treatment. Given the small sample size, results should be further confirmed.

Population Pharmacokinetic Analyses of Isoniazid in Tuberculosis Treatment: a Systematic Review

The aims of this systematic review are to provide knowledge concerning population pharmacokinetics of isoniazid (INH) and to identify factors influencing INH pharmacokinetic variability. Pubmed and Embase databases were systematically searched from inception to July, 2017. Relevant articles from reference lists were also included. All population pharmacokinetic studies of INH written in English, conducted in human (either healthy subjects or pulmonary tuberculosis patients) were included in this review. Ten studies were included in this review. Most studies characterized a two-compartment model with first-order kinetics for INH with a transit-compartment model for absorption suggested. Frequently reported significant predictors for INH clearance is NAT2 acetylator types (slow/intermediate/fast), while weight is a significant covariate for INH volume of distribution (both central and peripheral). In children, enzyme maturation had a profound affect on INH clearance.&#x0D; Keywords:&#x0D; Population pharmacokinetics, Isoniazid.&#x0D; References&#x0D; [1] World Health Organization, Global Tuberculosis Report 2019. https://apps.who.int/iris/bitstream/handle/10665/329368/9789241565714-eng.pdf (accessed 18 December 2019).[2] United Nations, Transforming our world: The 2030 agenda for sustainable development, New York, USA, 2015.[3] K. Takayama, L. Wang, H.L. David, Effect of isoniazid on the in vivo mycolic acid synthesis, cell growth, and viability of Mycobacterium tuberculosis, Antimicrob Agents Chemother 2.1 (1972) 29-35. https://doi.org/10.1128/aac.2.1.29 [4] A. Jindani, V.R. Aber, E. A. Edwards, D. A. Mitchison, The early bactericidal activity of drugs in patients with pulmonary tuberculosis. Am Rev Respir Dis 121(6) (1980) 939-49. https://doi.org/10.1164/arrd.1980.121.6.939 [5] P.R. Donald, The influence of human N-acetyltransferase genotype on the early bactericidal activity of isoniazid. Clin Infect Dis 39(10) (2004) 1425-30. https://doi.org/10.1086/424999 [6] D.A. Mitchison, Basic mechanisms of chemotherapy, Chest 76(6 Suppl) (1979) 771-81. https://doi.org/10.1378/chest.76.6_supplement.771 [7] H. McIlleron et al., Determinants of rifampin, isoniazid, pyrazinamide, and ethambutol pharmacokinetics in a cohort of tuberculosis patients, Antimicrob Agents Chemother 50(4) (2006) 1170-7. https://doi.org/10.1128/aac.50.4.1170-1177.2006 [8] S. Chideya et al., Isoniazid, rifampin, ethambutol, and pyrazinamide pharmacokinetics and treatment outcomes among a predominantly HIV-infected cohort of adults with tuberculosis from Botswana, Clin Infect Dis 48(12) (2009) 1685-94. https://doi.org/10.1086/599040 [9] N. Singh et al., Study of NAT2 gene polymorphisms in an Indian population: association with plasma isoniazid concentration in a cohort of tuberculosis patients. Mol Diagn Ther 13(1) (2009) 49-58. https://doi.org/10.1007/bf03256314 [10] N. Buchanan, C. Eyberg, M.D. Davis, Isoniazid pharmacokinetics in kwashiorkor. S Afr Med J 56(8) (1979) 299-300.[11] U.S. Food and Drug Administration (1999), "Guidance for Industry. Populationpharmacokinetics",Retrieved from http://www.fda.gov/downloads/Drugs/.../Guidances/UCM072137.pdf[12] D. R Mould, R. N. Upton, Basic concepts in population modeling, simulation, and model‐based drug development, CPT: pharmacometrics &amp; systems pharmacology 1(9) (2012) 1-14. https://doi.org/10.1038/psp.2012.4 [13] P. Denti et al., Pharmacokinetics of isoniazid, pyrazinamide, and ethambutol in newly diagnosed pulmonary TB patients in Tanzania, PLoS ONE 10(10) (2015), e0141002. https://doi.org/10.1371/journal.pone.0141002 [14] B. Guiastrennec et al., Suboptimal Antituberculosis Drug Concentrations and Outcomes in Small and HIV-Coinfected Children in India: Recommendations for Dose Modifications, Clin Pharmacol Ther 104(4) (2017), 733-741. https://doi.org/10.1002/cpt.987 [15] M. Kinzig-Schippers et al., Should we use N-acetyltransferase type 2 genotyping to personalize isoniazid doses?, Antimicrobial Agents and Chemotherapy 49(5) (2005), 1733-1738. https://doi.org/10.1128/aac.49.5.1733-1738.2005 [16] J.J. Kiser et al., Isoniazid pharmacokinetics, pharmacodynamics, and dosing in South African infants, Therapeutic Drug Monitoring 34(4) (2012) 446-451. https://doi.org/10.1097/ftd.0b013e31825c4bc3 [17] L. Lalande, Population modeling and simulation study of the pharmacokinetics and antituberculosis pharmacodynamics of isoniazid in lungs, Antimicrobial Agents and Chemotherapy 59(9) (2015) 5181-5189. https://doi.org/10.1128/aac.00462-15 [18] C. Magis-Escurra et al., Population pharmacokinetics and limited sampling strategy for first-line tuberculosis drugs and moxifloxacin, International Journal of Antimicrobial Agents 44(3) (2014) 229-234. https://doi.org/10.1016/j.ijantimicag.2014.04.019 [19] C.A. Peloquin et al., Population pharmacokinetic modeling of isoniazid, rifampin, and pyrazinamide, Antimicrobial Agents and Chemotherapy 41(12) (1997) 2670-2679. https://doi.org/10.1128/aac.41.12.2670 [20] K.Y. Seng et al., Population pharmacokinetic analysis of isoniazid, acetylisoniazid, and isonicotinic acid in healthy volunteers, Antimicrobial Agents and Chemotherapy 59(11) (2015) 6791-6799. https://doi.org/10.1128/aac.01244-15 [21] J.J. Wilkins et al., Variability in the population pharmacokinetics of isoniazid in South African tuberculosis patients, British Journal of Clinical Pharmacology 72(1) (2011) 51-62. https://doi.org/10.1111/j.1365-2125.2011.03940.x [22] S.P. Zvada et al., Population pharmacokinetics of rifampicin, pyrazinamide and isoniazid in children with tuberculosis: In silico evaluation of currently recommended doses, Journal of Antimicrobial Chemotherapy 69(5) (2014) 1339-1349. https://doi.org/10.1093/jac/dkt524 [23] World Health Organization, Guidance for national tuberculosis programmes on the management of tuberculosis in children (No. WHO/HTM/TB/2014.03). World Health Organization, 2014.[24] World Health Organization, &amp; Stop TB Initiative (World Health Organization), Treatment of tuberculosis: guidelines. World Health Organization, 2010.[25] J.S. Starke, S.M, Tuberculosis in: James D. Cherry, Ralph D. Feigin (Eds.), Textbook of Pediatric Infectious Diseases., Saunders: Philadelphia, 1998 pp. 1196-1238. [26] J.G. Pasipanodya, S. Srivastava, T. Gumbo, Meta-analysis of clinical studies supports the pharmacokinetic variability hypothesis for acquired drug resistance and failure of antituberculosis therapy, Clinical Infectious Diseases 55(2) (2012) 169-177. https://doi.org/10.1093/cid/cis353&#x0D;  

Development of a limited sampling strategy for the estimation of isoniazid exposure considering N-acetyltransferase 2 genotypes in Korean patients with tuberculosis

A limited sampling strategy (LSS) to estimate the exposure to isoniazid was developed considering N-acetyltransferase 2 (NAT2) genotypes in Korean patients with tuberculosis. The influence of the genotypes on the pharmacokinetics of isoniazid was also evaluated. A total of 33 participants participated in the study and received isoniazid 300 mg once daily. Evaluable participants consist of ten slow (SA), fourteen intermediate (IA) and six rapid acetylators (RA). As expected, isoniazid exposure was higher (mean AUC, 28.4 versus 7.6 mg*h/L) and systemic clearance lower (mean apparent clearance, 14.8 versus 50.6 L/h) in SAs than RAs. The formulas to estimate isoniazid exposure were constructed using one or more concentration-time points that correlate with the area under the concentration-time curve (AUC). The LSS using a formula of single concentration-time point at 4 h post dose (C4) is applicable for all acetylators to the therapeutic drug monitoring (TDM) of isoniazid in patients with tuberculosis when evaluated using the Deming regression and Bland-Altman plot (AUC = 1.53 + 10.03*C4, adjusted r2 = 0.95, p < 0.001). Considering that SAs are more prone to adverse effects, pre-dose NAT2 genotyping would be valuable for optimal isoniazid dosing in conjunction with TDM.

Genetic characterization of N-acetyltransferase 2 variants in acquired multidrug-resistant tuberculosis in Indonesia.

Background: Owing to the high resistance rate of tuberculosis (TB) to isoniazid, which is metabolized by N-acetyltransferase 2 (NAT2), we investigated the associations between NAT2 variants and multidrug-resistant (MDR)-TB. Materials & methods: The acetylator status based on NAT2 haplotypes of 128 patients with MDR-TB in Indonesia were compared with our published data from patients with anti-TB drug-induced liver injury (AT-DILI), TBand the general population. Results:NAT2*4 was more frequent in the MDR-TB group than in the AT-DILI group, TB controlsand general controls. NAT2*4/*4 was significantly more frequent in patients with MDR-TB than in those with AT-DILI. NAT2*5B/7B, *6A/6Aand *7B/*7B were detected at lower frequencies in patients with AT-DILI. Rapid acetylators were significantly more frequent in patients with MDR-TB than in those with AT-DILI. Conclusion: These results provide an initial data for optimizing TB treatment in the Indonesian population, and suggest that NAT2 genotyping may help to select appropriate treatment by predicting TB-treatment effect.