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
