Comparing Two Naloxone Tapering Methods in Management of Methadone Intoxication; a Quasi-experimental Study

Even though naloxone is the main treatment for methadone poisoning treatment there are controversiesabout the proper method of its tapering. This study aimed to compare two methods in this regard.

Thisstudy was a prospective, single-blind pilot quasi-experimental study on non-addicted adult patients poisoned withmethadone. Patients were randomly divided into 2 groups. In one group, after stabilization of respiratory conditionsand consciousness, naloxone was tapered using the half-life of methadone and in the other group, naloxone was taperedusing the half-life of naloxone. Recurrence of symptoms and changes in venous blood gas parameters were comparedbetween groups as outcome.

52 patients were included (51.92% female). 31 cases entered Group A (taperingbased on methadone’s half-life) and 21 cases entered Group B (tapering based on naloxone’s half-life). The two groupswere similar regarding mean age (p = 0.575), gender distribution (p = 0.535), the cause of methadone use (p = 0.599),previous medical history (p = 0.529), previous methadone use (p = 0.654), drug use history (p = 0.444), and vital signson arrival to emergency department (p = 0.054). The cases of re-decreasing consciousness during tapering (52.38% vs.25.81%; p = 0.049) and after discontinuation of naloxone (72.73% vs. 37.50%; p = 0.050) were higher in the tapering basedon naloxone half-life group. The relative risk reduction (RRR) for naloxone half-life group was -1.03 and for methadonehalf-life group was 0.51. The absolute risk reduction (ARR) was 0.27 (95% confidence interval (CI) = 0.01-0.53) and thenumber needed to treat (NNT) was 3.7 (95% CI= 1.87- 150.53). There was not any statistically significant difference be-tween groups regarding pH, HCO3, and PCO2changes during tapering and after naloxone discontinuation (P > 0.05).However, repeated measures analysis of variance (ANOVA), showed that in the tapering based on methadone’s half-lifegroup, the number of changes and stability in the normal range were better (p < 0.001).

It seems that, bytapering naloxone based on methadone’s half-life, not only blood acid-base disorders are treated, but they also remainstable after discontinuation and the possibility of symptom recurrence is reduced.