Genomewide Association Study Confirming the Association of NAT2 with Susceptibility to Antituberculosis Drug-Induced Liver Injury in Thai Patients.

Antituberculosis drug-induced liver injury (ATDILI) is a common side effect leading to tuberculosis (TB) treatment disruption. The mechanism of the disease remains poorly understood. We conducted a genomewide association study (GWAS) to investigate all possible genetic factors of ATDILI in Thai patients. This study was carried out in Thai TB patients, including 79 ATDILI cases and 239 tolerant controls from our network hospitals in Thailand. Nearly 1 million single-nucleotide polymorphisms (SNPs) were genotyped across the whole genome using an Illumina OmniExpress Exome BeadChip array. In the discovery stage, we identified strong association signals on chromosome 8 originating from the N-acetyltransferase (NAT2) region. The A allele of rs1495741, the top SNP in the intergenic region of NAT2 and PSD3 (14 kb from NAT2), was significantly associated with ATDILI (recessive model, odds ratio of 6.01 [95% confidence interval, 3.42 to 10.57]; P = 6.86E-11). This particular SNP was reported as a tag SNP for NAT2 inferred phenotypes. The AA, AG, and GG genotypes represented NAT2 slow acetylators, intermediate acetylators, and fast acetylators, respectively. The tag SNP genotypes demonstrated a concordance rate of 94.98% with NAT2 acetylator phenotypes. This GWAS shows that NAT2 is the most important risk factor for ATDILI in the Thai population.

Pharmacovigilance activities in ASEAN countries.

PURPOSE: This study aimed to explore the current landscape and identify challenges of pharmacovigilance (PV) among Association of Southeast Asian Nations (ASEAN) countries. METHODS: This cross-sectional survey collected data from May 2014 to December 2015. Questionnaires seeking to collect information on resources, processes, roles and responsibility, and functions of PV systems were sent to relevant persons in the ASEAN countries. Functions of PV centers were measured using the minimum World Health Organization requirements for a functional national PV system. Performances of PV centers were measured by the following: (1) the indicators related to the average number of individual case safety reports (ICSR); (2) presence of signal detection activities and subsequent action; and (3) contribution to the global vigilance database. RESULTS: Cambodia, Indonesia, Laos, Malaysia, the Philippines, Singapore, Thailand, and Vietnam completed the survey. PV systems in four surveyed countries (Indonesia, Malaysia, Singapore, and Thailand) achieved all aspects of the World Health Organization minimum requirement for a functional national PV system; the remaining countries were deemed to have unclear communication strategies and/or no official advisory committee. Average numbers of recent ICSR national returns ranged from 7 to 3817 reports/year/million population; three countries (Malaysia, Singapore, and Thailand) demonstrated good performance in reporting system and reported signal detection activities and subsequent actions. All participating countries had submitted ICSRs to the Uppsala Monitoring Center during the survey period (2013-2015). CONCLUSIONS: Four participating countries had functional PV systems. PV capacity, functionality, and legislative framework varied depending on local healthcare ecosystem networks. Implementing effective communication strategies and/or technical assistance from the advisory committee are needed to strengthen PV in ASEAN. Copyright © 2016 John Wiley & Sons, Ltd.

Candidate HLA genes for prediction of co-trimoxazole-induced severe cutaneous reactions.

BACKGROUND: Co-trimoxazole is a sulfonamide-containing antibiotic that is effective in the treatment of several infections and for prophylaxis of Pneumocystis jiroveci pneumonia. This drug has been reported as a common culprit drug for the Stevens-Johnson syndrome (SJS) and for toxic epidermal necrolysis (TEN). Human leukocyte antigens (HLAs) play a key role in the immunopathogenesis of severe cutaneous reactions induced by several drugs. This study investigated the association between the HLA class I and HLA-DRB1 polymorphisms and co-trimoxazole-induced SJS/TEN in a Thai population. METHODS: Forty-three patients with co-trimoxazole-induced SJS/TEN and 91 co-trimoxazole-tolerant patients were enrolled in the study. HLA class I and HLA-DRB1 were genotyped using the reverse sequence-specific oligonucleotide probe method. RESULTS: The frequencies of three alleles of HLA, namely HLA-B*15:02, HLA-C*06:02, and HLA-C*08:01, were significantly higher in the co-trimoxazole-induced SJS/TEN group compared with controls. The risks for co-trimoxazole-induced SJS/TEN in patients with the HLA-B*15:02, HLA-C*06:02, or HLA-C*08:01 allele were about 3-11-fold higher when compared with those who did not carry one of these alleles. Individuals who carried the HLA-B*15:02-C*08:01 haplotype had a 14-fold higher risk for co-trimoxazole-induced SJS/TEN. CONCLUSION: Evidence of associations between co-trimoxazole-induced SJS/TEN and HLA alleles including HLA-B*15:02, HLA-C*06:02, and HLA-C*08:01 were found in the study population. These findings may suggest that apart from the HLA molecules, other molecules involved in the molecular pathogenesis of these severe cutaneous adverse drug reactions may play an important role in the susceptibility of individuals to SJS/TEN caused by co-trimoxazole.

Renin angiotensin system blockers-associated angioedema in the Thai population: analysis from Thai National Pharmacovigilance Database.

BACKGROUND: Renin-angiotensin-aldosterone system (RAS) blockers are commonly used for cardiovascular diseases. Currently, little information exists for the Asian population on angioedema, a rare yet serious adverse event. OBJECTIVE: This study aimed to describe characteristics of RAS blockers-associated angioedema (RASBA) in Thai patients. METHODS: A retrospective study using the national pharmacovigilance database of Thailand was undertaken. Cases indicating the presence of angioedema with RAS blockers uses from 1984-2011 were identified. Patient demographics, co-morbidities, concomitant drugs, information for the RAS blockers and angioedema were obtained as well as causality assessment and quality of reports. RESULTS: A total of 895 cases were identified. Mean age was 59.9+12.8 years and 66.5% being female. Most angioedema events (48.6%) occurred during the first week of treatment. Angiotensin converting enzyme inhibitors (87.7%) were the most commonly implicated agents followed by angiotensin receptor blockers (10.5%), aldosterone antagonist (2.1%) and direct renin inhibitor (0.2%). Out of the 895 cases incorporated in this study, 165 (18.4%) were classified as serious events and resulted in hospitalization. The overall case fatality rate was 0.4%. Respiratory disturbance occurred in 46 cases (5.1%). Patients with respiratory complications tended to be younger (53.4+13.9 vs 60.3+12.7 years old; p=0.002) and with higher frequency of allergy history (26.1% vs 14.7%; p=0.032) compared to those without respiratory complications. Based on multivariate logistic regression, the adjusted OR for history of allergy was 2.23 (95%CI: 1.04 - 4.78, p = 0.041). CONCLUSIONS: RASBA in Thai population occurred mostly in elderly female patients and often led to hospitalization. Since large number of patients is regularly exposed to RAS-blockers, a nationwide attempt to raise awareness of clinicians when prescribing RAS-blockers is prudent.

Signal detection for Thai traditional medicine: examination of national pharmacovigilance data using reporting odds ratio and reported population attributable risk.

Herbal containing medicine consumption has increased while the awareness of adverse drug reaction (ADR) was less than conventional medicine. Early detection of unexpected numbers of ADRs from herbal medicines' reports which are abnormal from the whole database needs quantification. Disproportionality analysis has been performed for signal detection by using reporting odds ratio (ROR) as measurement. The impact of having medicine as exposures in each ADR should be measured by using reported population attributable risks (RPAR). This study aimed to quantify the contribution of Thai traditional medicine (TTM) to ADR reports and to assess the association between TTMs and serious adverse drug reactions. Data were retrieved from the adverse drug reaction surveillance database, Thai-Food and Drug Administration from 2002 to 2013. Crude and adjusted RORs for each drug-ADR pair and RPARs were computed. TTM contributed only 0.001% of all serious ADRs reported. Out of 4208 TTM-ADR pairs were examined, three had the statistically significant RORs, namely Andrographis paniculata and anaphylactic shock (ROR 2.32, 95% CI 1.03, 5.21); green traditional medicine and Stevens-Johnson syndrome (ROR 13.04, 95% CI 5.4-31.51) and Derris scandens Benth and angioedema (ROR 2.71, 95% CI 1.05-6.95). Their RPARs ranged from 0.05% to 0.16%. We conclude that TTMs need more intensive surveillance.

Characterization of hypersensitivity reactions reported among Andrographis paniculata users in Thailand using Health Product Vigilance Center (HPVC) database.

BACKGROUND: Andrographis paniculata (andrographis) is one of the herbal products that are widely used for various indications. Hypersensitivity reactions have been reported among subjects receiving Andrographis paniculata in Thailand. Understanding of characteristics of patients, adverse events, and clinical outcomes is essential for ensuring population safety.This study aimed to describe the characteristics of hypersensitivity reactions reported in patients receiving andrographis containing products in Thailand using national pharmacovigilance database. METHODS: Thai Vigibase data from February 2001 to December 2012 involving andrographis products were used. This database includes the reports submitted through the spontaneous reporting system and intensive monitoring programmes. The database contained patient characteristic, adverse events associated with andrographis products, and details on seriousness, causality, and clinical outcomes. Case reports were included for final analysis if they met the inclusion criteria; 1) reports with andrographis being the only suspected cause, 2) reports with terms consistent with the constellation of hypersensitivity reactions, and 3) reports with terms considered critical terms according to WHO criteria. Descriptive statistics were used. RESULTS: A total of 248 case reports of andrographis-associated adverse events were identified. Only 106 case reports specified andrographis herbal product as the only suspected drug and reported at least one term consistent with constellation of hypersensitivity reactions. Most case reports (89%) came from spontaneous reporting system with no previously documented history of drug allergy (88%). Of these, 18 case reports were classified as serious with 16 cases requiring hospitalization. For final assessment, the case reports with terms consistent with constellation of hypersensitivity reactions and critical terms were included. Thirteen case reports met such criteria including anaphylactic shock (n = 5), anaphylactic reaction (n = 4) and angioedema (n = 4). Time to development of symptoms ranged from 5 minutes to 1 day. The doses of andrographis used varied from 352 mg to 1,750 mg. Causality assessment of 13 case reports were certain (n = 3), probable (n = 8) and possible (n = 2). CONCLUSIONS: Our findings suggested that hypersensitivity reactions have been reported among patients receiving Andrographis paniculata. Healthcare professionals should be aware of this potential risk. Further investigation of the causal relationship is needed; meanwhile including hypersensitivity reactions for andrographis product labeling should be considered.

Thai stakeholders' awareness and perceptions of the patient adverse event reporting system for herbal medicines: a qualitative study.

BACKGROUND: In Thailand, the consumption of herbal medicines has been increasing. Adverse events (AEs) of herbal medicines have been identified through the spontaneous reporting system. However, the number of patients reporting AEs of herbal medicines remains limited. AIM: To explore the awareness and perceptions about the patient reporting system and to explore attitudes towards safety of herbal medicines, experiences, and intention to report AEs of herbal medicines. METHOD: Semi-structured in-depth interviews were conducted with stakeholders (patients, community pharmacists, village health volunteers, and consumers who had experienced submitting a complaint about health products to the Consumers Foundation). Additionally, a focus group discussion was held with stakeholders (academics, herbal medicine manufacturers, healthcare professionals, policy maker who was responsible for promoting the use of herbal medicines, pharmacovigilance staff, patient, and representative from patient organisations). The data were audio recorded, transcribed verbatim and analysed using thematic analysis. RESULTS: Fifty participants were interviewed and the focus group discussion included 12 participants. Patients had positive attitudes towards the safety of herbal medicines. Lack of awareness of the patient reporting system was identified. Nevertheless, all stakeholders acknowledged the importance of the safety monitoring of herbal medicines and indicated a willingness to report AEs via the patient reporting system in the future. A simple reporting system, a variety of reporting channels, the provision of feedback, and providing rewards would motivate patients to report AEs. CONCLUSION: Although there is a lack of awareness, this provides a great opportunity to improve patient AE reporting system for herbal medicines in Thailand.

Comparison of Patient Adverse Drug Reaction Reporting Systems in Nine Selected Countries.

Patients are recognized as important players in the pharmacovigilance system. This study aims to describe and compare the characteristics of patient reporting systems, reporting forms, awareness raising-activities, and the statistics related to patient reporting in the selected countries. Fifteen countries (eight Western countries and seven Asian countries) were purposively selected. A questionnaire survey was distributed to national pharmacovigilance authorities in those countries. Nine countries (five Western countries and four Asian countries) returned the questionnaire. A review of the websites of national pharmacovigilance centres was conducted. The proportion of patient reports in the selected Western countries ranged from 57.83% to 14.37%, while it was accounted for less than 1% in the selected Asian countries. Currently, patients in all nine countries can report adverse drug reactions online via a website. The number of clicks from the national pharmacovigilance website to reach the online reporting form range from one to five clicks. Countries with higher patient reporting rates seemed to share the following characteristics; provision of feedback, engagement with patient organizations, and implementation of several activities to raise the awareness of the general public on the importance of pharmacovigilance. To increase the number of patient reports, the strengths of each country's system should be adopted.

Research Directions in Genetic Predispositions to Stevens-Johnson Syndrome / Toxic Epidermal Necrolysis.

Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) is one of the most devastating of adverse drug reactions (ADRs) and was, until recently, essentially unpredictable. With the discovery of several risk alleles for drug-induced SJS/TEN and the demonstration of effectiveness of screening in reducing incidence, the stage is set for implementation of preventive strategies in populations at risk. Yet much remains to be learned about this potentially fatal complication of commonly used drugs.

Clinical application of pharmacogenomics: the example of HLA-based drug-induced toxicity.

Pharmacogenomics is gradually becoming more and more indispensable in modern medicine. In several cases, a pharmacogenomics test may alleviate serious drug-induced adverse reactions, if it precedes drug prescription. In this article, we provide an overview of the well-established HLA-based carbamazepine- and allopurinol-induced adverse reactions, as one of the most characteristic examples of the clinical application of pharmacogenomics, highlighting its regional impact in Southeast Asian populations in preventing adverse reactions of certain drug/allele pairs. This example provides useful insights towards evidence generation for policy implementation, including economic evaluation analysis, the implementation of pharmacogenomics testing procedures and monitoring of policy effectiveness, hence serving, per se or in the context of international collaborative efforts, as a model for similar cases in several national healthcare systems worldwide.

Characterization of Statin-Associated Myopathy Case Reports in Thailand Using the Health Product Vigilance Center Database.

BACKGROUND: HMG-CoA reductase inhibitors [statins], a widely prescribed cholesterol-lowering therapy, are associated with muscle-related adverse events. While characteristics of such events are well documented in Western countries, little data exists for the Thai population. OBJECTIVE: The aim of this study was to determine the characteristics of patients, type and dosing of statin, and to identify patterns of drug use that may be associated with such adverse events using the national pharmacovigilance database known as Thai Vigibase. METHOD: Muscle-related adverse events involving statins in the Thai Vigibase from 1996 to December 2009 were identified. For each report, the following information was extracted: patient demographics, co-morbidities, detailed information of adverse event, detailed information of suspected drug, treatment and outcome, as well as causality assessment and quality of reports. Descriptive statistics were performed for all study variables. RESULTS: A total of 198 cases of statin-associated muscle-related adverse events were identified. Mean age was 61.4 ± 12.4 years of age and 59.6% were female. Simvastatin, atorvastatin, rosuvastatin and cerivastatin were implicated as the suspected drug in 163 (82.3%), 24 (12.1%), 10 (5.1%) and 1 (0.5%) cases, respectively. Rhabdomyolysis accounted for 55.6% of all muscle-related adverse events. Drug interactions known to enhance such toxicity of statins were identified in 40.9% of the total set of reports. Similar to studies from Western countries, fibrates, HIV protease inhibitors, non-dihydropyridine calcium channel blockers, azole antifungals and macrolides were commonly found in such cases. Interestingly, colchicine has been identified as the second most common drug interaction in our database. Case fatality rates were 0.9, 1.6 and 16.7%, when there were 0, 1 and ≥2 interacting drugs, respectively. CONCLUSIONS: Characteristics of muscle-related adverse events with statins in the Thai population showed some similarities and differences compared with Western countries. Such similarities included advanced age, female sex, certain co-morbidities and drug interactions. While the majority of interacting drugs are well known, a big proportion of cases of statin-colchicine interaction attributed to long-term use of colchicine in Thailand was noted and should be further investigated. Based on these results, an attempt to avoid dangerous and well-known drug interactions among statin users should be implemented nationwide.

Safety of herbal products in Thailand: an analysis of reports in the thai health product vigilance center database from 2000 to 2008.

BACKGROUND: The use of herbal products continues to expand rapidly across the world and concerns regarding the safety of these products have been raised. In Thailand, Thai Vigibase, developed by the Health Product Vigilance Center (HPVC) under the Thai Food and Drug Administration, is the national database that collates reports from health product surveillance systems and programmes. Thai Vigibase can be used to identify signals of adverse events in patients receiving herbal products. OBJECTIVES: The purpose of the study was to describe the characteristics of reported adverse events in patients receiving herbal products in Thailand. METHODS: Thai Vigibase data from February 2000 to December 2008 involving adverse events reported in association with herbal products were used. This database includes case reports submitted through the spontaneous reporting system and intensive monitoring programmes. Under the spontaneous reporting system, adverse event reports are collected nationwide via a national network of 22 regional centres covering more than 800 public and private hospitals, and health service centres. An intensive monitoring programme was also conducted to monitor the five single herbal products listed in the Thai National List of Essential Medicines (NLEM), while another intensive monitoring programme was developed to monitor the four single herbal products that were under consideration for inclusion in the NLEM. The database contained patient demographics, adverse events associated with herbal products, and details on seriousness, causality and quality of reports. Descriptive statistics were used for data analyses. RESULTS: A total of 593 reports with 1868 adverse events involving 24 different products were made during the study period. The age range of individuals was 1-86 years (mean 47 years). Most case reports were obtained from the intensive monitoring programme. Of the reports, 72% involved females. The herbal products for which adverse events were frequently reported were products containing turmeric (44%), followed by andrographis (10%), veld grape (10%), pennywort (7%), plai (6%), jewel vine (6%), bitter melon (5%) and snake plant (5%). Gastrointestinal problems were the most common adverse effect reported. Serious adverse events included Stevens-Johnson syndrome, anaphylactic shock and exfoliative dermatitis. CONCLUSIONS: Adverse event reports on herbals products were diverse, with most of them being reported through intensive monitoring programmes. Thai Vigibase is a potentially effective data source for signal detection of adverse events associated with herbal products.