The Conversion Ratio From Intravenous Hydromorphone to Oral Opioids in Cancer Patients

Area of Science:

• Oncology
• Palliative Care
• Pharmacology

Background:

• Accurate conversion ratios (CR) for intravenous (IV) hydromorphone to oral hydromorphone and opioid rotation ratios (ORR) to oral morphine equivalent daily dose (MEDD) are vital for effective cancer pain management.
• Knowledge gaps in these ratios can lead to inadequate pain control or overdosing in cancer inpatients.

Purpose of the Study:

• To determine the conversion ratio (CR) from IV hydromorphone to oral hydromorphone.
• To determine the opioid rotation ratio (ORR) from IV hydromorphone to MEDD, including oral morphine and oxycodone.

Main Methods:

• Retrospective review of 4745 inpatient palliative care consults (2010-2014).
• Analysis of patients converted from IV hydromorphone to oral hydromorphone, morphine, or oxycodone, focusing on those discharged on oral opioids without readmission within one week.
• Linear regression used to estimate CR and ORR based on 24-hour IV hydromorphone dose and oral opioid dose at discharge.

Main Results:

• The median CR from IV to oral hydromorphone was 2.5 (95% CI 2.14-2.75), with a correlation of 0.95.
• The median ORR from IV hydromorphone to MEDD was 11.46 (95% CI 9.84-13.00), with a correlation of 0.93.
• Patients receiving ≥30 mg/day of IV hydromorphone had a lower median ORR (9.86) compared to those receiving <30 mg/day (11.54).

Conclusions:

• 1 mg of IV hydromorphone is equivalent to 2.5 mg of oral hydromorphone and 11.46 mg of MEDD.
• Higher doses of IV hydromorphone (≥30 mg/day) may necessitate a lower opioid rotation ratio when switching to other oral opioids.