Opioid rotation to alfentanil: comparative evaluation of conversion ratios

The conversion ratio of subcutaneous diamorphine to alfentanil was recently compared in a study at two specialist palliative care (SPC) units. Alfentanil is widely used as an opioid analgesic for people with renal failure. The use of alfentanil in palliative care was first described in 1995.1 Four patients with opioid toxicity and renal impairment were converted from diamorphine to subcutaneous alfentanil, with resolution of agitation. A conversion ratio of 10:1 diamorphine to alfentanil was used based on discussions with anaesthetists.1 This ratio has been incorporated widely into prescribing guidance despite a limited evidence base.2 ,3 Clinical observation at one SPC unit showed that the dose of alfentanil was almost always increased from the initial dose and a 6:1 conversion ratio was subsequently adopted. The aim of the study was to compare the conversion ratio of subcutaneous diamorphine to alfentanil and subsequent dose titrations of alfentanil in two SPC units (A and B) that use different conversion ratios. SPC unit A uses 6:1, while unit B uses 10:1. A retrospective healthcare record review of consecutive inpatients who received alfentanil via continuous subcutaneous infusion was performed. The project was registered with the audit department for each unit. Following consultation with the local research department, it was established that ethical approval was not required. Patients were identified using controlled drug books. Data on demographics, diagnosis, indication for alfentanil, opioid use in …