Practicability, safety, and efficacy of a "German model" for opioid conversion to oral levo-methadone

Abstract

Introduction: An algorithm to convert from any other opioid to oral levo-methadone was developed in Germany, the German model of levo-methadone conversion (GMLC). According to this GMLC, the pre-existing opioid is stopped, then titration of oral levo-methadone is initiated with a starting dose of 5 mg orally q 4 h (plus prn q 1 h). If necessary, levo-methadone dose is increased (pain) or decreased (side effects) by 30% q 4 h (plus prn q 1 h). After 72 h, the achieved single dose is maintained, but the dosing interval increases twofold to q 8 h (plus prn q 3 h). The aim of this study was to obtain information about the practicability, safety, and efficacy of the GMLC in clinical routine.

Methods: A retrospective, systematic chart review of levo-methadone conversions for the treatment of pain in inpatient palliative care was performed.

Results: Fifty-two patients were analyzed. The dosing interval was increased correctly after 72 h as demanded by the GMLC in 60% of patients. In 85% of the patients, opioid medication with levo-methadone could be maintained until the end of the inpatient stay. In three patients (6%), levo-methadone administration had to be stopped due to side effects. No serious adverse events could be detected during opioid rotation. Pain intensity was reduced significantly (p < 0.001) after conversion concerning mean (NRS 0.9; range 0-4) and maximum pain over the day (NRS 3.9; range 0-10).

Conclusion: The presented study indicates that the GMLC provides a practical and reasonably safe approach to perform opioid rotation to levo-methadone in a palliative care setting.