A new study has shown harmful prescription patterns of powerful painkillers among a substantial number of Ontario patients who received methadone therapy to treat their opioid addiction. Methadone, which is a type of long-acting opioid, has proven to be an effective therapy for opioid dependence. According to a new study by the Centre for Addiction and Mental Health (CAMH) and Institute for Clinical Evaluative Sciences (ICES), 18% of methadone maintenance therapy patients also received prescriptions for more than a week’s supply of other opioids.