Evaluation of initial methadone dosing for prevention of iatrogenic opioid abstinence syndrome in children

Abstract

Methadone is commonly prescribed for prevention of iatrogenic opioid abstinence syndrome (IOAS) in critically ill children. However, there is a paucity of data on the recommended initial dosage requirements. Data was retrospectively collected from January--December 31, 2008 and included demographics, methadone regimen, and IOAS symptoms. The primary objective was to determine the initial methadone dosing utilized (i.e., mg/kg/day) and the impact that this had on the number of dosage changes required for prevention of IOAS in patients < 18 yr within 72 hr following discontinuation of opioid continuous infusion (CI). Secondary objectives included a comparison of methadone dose changes within 72 hr of intravenously opioid discontinuation and opioid CI requirements based on initial doses above and below the median level (i.e., mg/kg/day). Between-group analysis was performed using descriptive and inferential statistics. A step-wise regression was employed to assess relationships between the initial dose (mg/kg/day) and several independent variables. Fifty-five patients were included for analysis. The median initial dose was 0.84 mg/kg/day. The “low-dose” group included patients receiving < 0.84 mg/kg/day (n = 27); the “high-dose” group included patients receiving ≥; 0.84 mg/kg/day (n = 28). The majority of patients (81.8%) received doses every 6 hr. Twenty-three patients (41.8%) developed IOAS and required an increase in dose while six patients (10.9%) required a decrease. No significant differences were found between groups. The cumulative and peak fentanyl CI doses were the only significant predictors of total mg/kg/day dose of methadone (P < 0.01). The initial methadone dosage regimens varied greatly in our patients. Approximately half required a change in their methadone dose. Based on our findings and a review of the literature, there is not a one-size fits all approach for determination of the initial methadone dose. Adoption of a consistent monitoring tool should be utilized for all children across the continuum of care to prevent IOAS and the over-sedation noted with excessive methadone dosing.

Keywords

Children - methadone - opioid withdrawal