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Pharmacogenomics study in a Taiwan methadone maintenance cohort.

ABSTRACT: Pharmacogenomics is research to study the drug treatment responses in subgroups of patients according to their genetic variants or genetic expression information. Methadone maintenance treatment, which is usually prescribed for patients with heroin dependence, was launched in Taiwan by the government in 2006. In this study, 366 patients who had taken methadone continually in the previous 7 days were examined. Data from administration of the Treatment Outcomes Profile (TOP), Severity of Dependence Scale (SDS), Clinical Opioid Withdrawal Scale (COWS), and Treatment Emergent Symptoms Scale (TESS) were obtained from patients' report records. Genes encoding the liver cytochrome P-450 (CYP) enzymes that are involved with the metabolism of methadone (CYP2B6, 3A4 and 2C19) were selected and genotyped in this cohort. We found that the SNPs on CYP2B6 were associated with plasma S-methadone concentration; SNPs on CYP3A4 were associated with withdrawal symptoms and side effects; and SNPs on CYP2C19 were associated with methadone dose. SNPs in the genes encoding the morphine phase II metabolic enzyme, UGT2B7, were associated with withdrawal symptom scores. In pharmacodynamic genes, the SNPs on OPRM1 were associated with insomnia and change in libido side effects. We conclude that SNP markers may be useful for future methadone dosage adjustment and to reduce adverse reactions.

SUBMITTER: Wang SC

PROVIDER: S-EPMC4179242 | biostudies-literature | 2013 Dec

REPOSITORIES: biostudies-literature

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Pharmacogenomics study in a Taiwan methadone maintenance cohort.

Wang Sheng-Chang SC Tsou Hsiao-Hui HH Ho Ing-Kang IK Lin Keh-Ming KM Liu Yu-Li YL

Journal of food and drug analysis 20131201 4

Pharmacogenomics is research to study the drug treatment responses in subgroups of patients according to their genetic variants or genetic expression information. Methadone maintenance treatment, which is usually prescribed for patients with heroin dependence, was launched in Taiwan by the government in 2006. In this study, 366 patients who had taken methadone continually in the previous 7 days were examined. Data from administration of the Treatment Outcomes Profile (TOP), Severity of Dependenc ...[more]

PMID: 25278738

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Project description:BackgroundIndividuals with criminal histories have high rates of opioid dependence and mortality. Excess mortality is largely attributable to overdose deaths. Methadone maintenance treatment (MMT) is one of the best evidence-based opioid substitution treatments (OSTs), but there is uncertainty about whether methadone treatment reduces the risk of mortality among convicted offenders over extended follow-up periods. The objective of this study was to investigate the association between adherence to MMT and overdose fatality as well as other causes of mortality.Methods and findingsWe conducted a retrospective cohort study involving linked population-level administrative data among individuals in British Columbia (BC), Canada with a history of conviction and who filled a methadone prescription between January 1, 1998 and March 31, 2015. Participants were followed from the date of first-dispensed methadone prescription until censoring (date of death or March 31, 2015). Methadone was divided into medicated (methadone was dispensed) and nonmedicated (methadone was not dispensed) periods and analysed as a time-varying exposure. Hazard ratios (HRs) with 95% CIs were estimated using multivariable Cox regression to examine mortality during the study period. All-cause and cause-specific mortality rates were compared during medicated and nonmedicated methadone periods. Participants (n = 14,530) had a mean age of 34.5 years, were 71.4% male, and had a median follow-up of 6.9 years. A total of 1,275 participants died during the observation period. The overall all-cause mortality rate was 11.2 per 1,000 person-years (PYs). Participants were significantly less likely to die from both nonexternal (adjusted HR [AHR] 0.27 [95% CI 0.23-0.33]) and external (AHR 0.41 [95% CI 0.33-0.51]) causes during medicated periods, independent of sociodemographic, criminological, and health-related factors. Death due to infectious diseases was 5 times lower (AHR 0.20 [95% CI 0.13-0.30]), and accidental poisoning (overdose) deaths were nearly 3 times lower (AHR 0.39 [95% CI 0.30-0.50]) during medicated periods. A competing risk regression demonstrated a similar pattern of results. The use of a Canadian offender population may limit generalizability of results. Furthermore, our observation period represents community-based methadone prescribing and may omit prescriptions administered during hospital separations. Therefore, the magnitude of the protective effects of methadone from nonexternal causes of death should be interpreted with caution.ConclusionsAdherence to methadone was associated with significantly lower rates of death in a population-level cohort of Canadian convicted offenders. Achieving higher rates of adherence may reduce overdose deaths and other causes of mortality among offenders and similarly marginalized populations. Our findings warrant examination in other study centres in response to the crisis of opiate-involved deaths.

Project description:BackgroundApproximately 1800 opioid treatment programs (OTPs) in the US dispense methadone to upwards of 400,000 patients with opioid use disorder (OUD) annually, operating under longstanding highly restrictive guidelines. OTPs were granted novel flexibilities beginning March 15, 2020, allowing for reduced visit frequency and extended take-home doses to minimize COVID exposure with great variation across states and sites. We sought to use electronic health records to compare retention in treatment, opioid use, and adverse events among patients newly entering methadone maintenance in the post-reform period in comparison with year-ago, unexposed, controls.MethodsRetrospective observational cohort study across 9 OTPs, geographically dispersed, in the National Institute of Drug Abuse (NIDA) Clinical Trials Network. Newly enrolled patients between April 15 and October 14, 2020 (post-COVID, reform period) v. March 15-September 14, 2019 (pre-COVID, control period) were assessed. The primary outcome was 6-month retention. Secondary outcomes were opioid use and adverse events including emergency department visits, hospitalizations, and overdose.Findings821 individuals were newly admitted in the post-COVID and year-ago control periods, average age of 38.3 (SD 11.1), 58.9% male. The only difference across pre- and post-reform groups was the prevalence of psychostimulant use disorder (25.7% vs 32.9%, p = 0.02). Retention was non-inferior (60.0% vs 60.1%) as were hazards of adverse events in the aggregate (X2 (1) = 0.55, p = 0.46) in the post-COVID period. However, rates of month-level opioid use were higher among post-COVID intakes compared to pre-COVID controls (64.8% vs 51.1%, p < 0.001). Moderator analyses accounting for stimulant use and site-level variation in take-home schedules did not change findings.InterpretationPolicies allowing for extended take-home schedules were not associated with worse retention or adverse events despite slightly elevated rates of measured opioid use while in care. Relaxed guidelines were not associated with measurable increased harms and findings could inform future studies with prospective trials.FundingUSDHHSNIDACTNUG1DA013035-15.

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Pharmacogenomics study in a Taiwan methadone maintenance cohort.

Publications

Pharmacogenomics study in a Taiwan methadone maintenance cohort.

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