Naltrexone in Unintentional Methadone Poisoning

Methadone toxicity is rising not only in those who are under maintenance methadone therapy (MMT) treatment but also in those who face accidentally to drugs, which result in increased morbidity and mortality. Naloxone is used for the treatment of methadone poisoning. The aim of this study was to evaluate the effect of oral naltrexone on treatment of unintentional methadone poisoning.
The study was a prospective clinical trial, included 64 patients with clinical signs of methadone intoxication who were referred to Noor and Ali-Asghar Hospital Poison Center between October 2013 and October 2014 in Isfahan, Iran. Patients were randomly divided into two groups: intervention and control. Both groups received naloxone 0.4 mg IV due to loss of consciousness with or without respiratory depression however the intervention group also received naltrexone 25 mg capsule after awaking. The vital signs in both groups were studied during hospitalization. The variables were compared using t test, ANOVA, chi-square and Mann-Whitney tests.
Findings: The mean ± SD age of patients in the group receiving naltrexone was 29.58 ± 9.21 years and in control group was 30.33 ± 9.25 years. Heart rate four hours after taking naloxone in the group receiving naltrexone and control group was 81.37 ± 5.93 and 86.71 ± 4.92, respectively (P = 0.032). By eliminating time as confounding factor, respiratory rate was significantly different between the two groups, that in the control group was lower than intervention (P = 0.005). All patients survived without complications.
This study showed that patients receiving naltrexone due to methadone poisoning had less respiratory depression and tachycardia.