Background
Complex pain in pediatric patients often is a mix of nociceptive and neuropathic origin and is a challenge to treat effectively to an acceptable pain level. A multimodal approach is recommended. Even so the use of this approach does not alleviate pain in a small group of patients. Methadone is an opioid with “rich pharmacology” and some studies in adult oncology patients have shown a good analgesic effect when adding a low-dose methadone to the ongoing opioid therapy. 
Methods 
At Astrid Lindgren children’s hospital we have used the low-dose methadone strategy as an addition to ongoing opioid therapy (as part of a multimodal analgesic treatment) in complex pain in pediatric patients for the last 10 years. The dose of methadone used is most often 0.1 mg/kg x 2-3 times daily. In neonates and small infants, a reduced dose is used. Methadone is administered intravenously or orally.
Results
Since the start of using the low-dose methadone approach we have treated almost 200 pediatric patients with complex pain. Looking at retrospective data median age was 8.5 years with a range 1 month to 18 years. More than 50 % of patients had undergone major surgery, about 30 % of patients were oncology patients mostly with treatment related pain problems. A small number were palliative patients.
Conclusion
Adding low-dose methadone has had a major clinical effect on alleviating pain in complex pain in pediatric patients and is routinely used in our hospital.

PROMISING CLINICAL EFFECT OF ADDING LOW-DOSE METHADONE IN THE TREATMENT OF COMPLEX PAIN IN PEDIATRIC PATIENTS