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Alfentanil conversion ratios and successful analgesia
  1. Amy Taylor and
  2. Carol Stone
  1. Palliative Medicine, Marie Curie Hospice Belfast, Belfast, UK
  1. Correspondence to Dr Amy Taylor, Marie Curie Hospice Belfast, Belfast BT5 6NF, UK; amygstaylor{at}

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Opioid switch is often used to improve analgesic response or reduce adverse effects. Evidence for opioid rotation and equianalgesia is lacking, with many conversion ratios derived from pharmaceutical industry data without clinical confirmation.1 Alfentanil is widely used in renal failure. Despite limited evidence, a conversion ratio of 10:1 diamorphine to alfentanil was historically suggested,2 which has since been widely incorporated into prescribing guidance. This specialist palliative care (SPC) unit routinely uses this conversion ratio and wanted to review local practice and evaluate the need for change. A retrospective healthcare record review of hospice inpatients who received alfentanil via continuous subcutaneous infusion in 2017 assessed conversion ratios of twenty-five patients on day 1, reduced to eight patients by day 5. It concluded that a conversion ratio of 6:1 diamorphine to alfentanil was clinically appropriate.3 The study did not analyse impact on opioid toxicity or breakthrough use.


The aims of this study were:

  • To assess the conversion ratios used in opioid switch to alfentanil initially and when steady dose reached.

  • To identify the effect of switch to alfentanil on breakthrough opioid use, opioid toxicity and pain control.

  • To identify the clinical characteristics of patients who undergo opioid switch to alfentanil in an SPC unit.


This was a retrospective analysis of case notes relating to patients who were prescribed alfentanil from 2018 to 2020 …

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  • Contributors AT is responsible for the literature review, planning, data collection, analysis and interpretation, and drafted the manuscript. CS conceived the study, contributed to planning and data interpretation, and edited the manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; internally peer reviewed.