Rapidly escalating doses of subcutaneous alfentanil (versus subcutaneous morphine) in palliative care inpatients: a case note review study

The aim of this study was to investigate acute opioid dose changes among patients started on a continuous subcutaneous infusion (CSCI) containing alfentanil or morphine within a specialist palliative care inpatient unit.

This was a retrospective case note review of all inpatients admitted to a specialist palliative care unit during a 12-month period. The data collected included previous opioid analgesic, previous opioid regular dosage, opioid in CSCI, opioid in CSCI dosage (day 0 to day 7), duration of CSCI and reason for ending CSCI (if applicable).

After 7 days, 64% of patients receiving morphine were on a higher dose, 29% remained on the same dose, and 7% were on a lower dose. Likewise, after 7 days, 73.5% of patients receiving alfentanil were on a higher dose, 20.5% remained on the same dose, and 6% were on a lower dose. A statistically significant difference between the percentage change in opioid dose at 7 days between the two groups was found, that is, alfentanil greater than morphine (p=0.04724).

This study review found that many patients commenced on an opioid CSCI required dose escalation over the first 7 days, although dose escalation was more common and was of a greater amount in patients receiving alfentanil as compared with those receiving morphine. Given the results, it is difficult to exclude the possibility of the development of pharmacological tolerance (ie, pharmacodynamic tolerance and/or pharmacokinetic tolerance) in some patients receiving alfentanil.