IRCT2012062910133N1 IRCT 2013-03-22 Loghman-Hakim Toxicological Reserch Center dependent to Shahid-Beheshti University The role of naltrexone in opioid toxicity The efficacy of oral naltrexone to maintain normal ventilation after acute methadone Poisoning in Opioid non-dependent Patients 2012-11-20 anticipated 60 Complete https://irct.ir/trial/10598 interventional Randomization: Randomized, Blinding: Double blinded, Placebo: Used, Assignment: Parallel, Purpose: Treatment. N/A Acute Opioids Toxicity. Intervention 1: Intervention group; After emergency management (if needed) the patients in intervention group will take a single dose of 50mg naltrexone orally . During the hospital stay, the prevalence of respiratory depression or respiratory arrest, and loss of consciousness will be assess in these patients hourly by physical examination and monitoring of oxygenation and CO2 pressure of the blood (based on arterial blood gases analysis), and the O2 saturation by pulse oxymetery. Intervention 2: Control group; The patients in control group after emergency management (if needed) will take a placebo drug. These patient during hospital admission will monitor regarding to respiratory depression or arrest and loss of consciousness by hourly physical examination, arterial Pco2 and oxygenation by arterial blood gas and pulseoxymetery respectively.