CLINICAL ANALGESIC EQUIVALENCE FOR MORPHINE AND HYDROMORPHONE WITH PROLONGED PCA

A morphine to hydromorphone equivalence ratio of 7:1 has become the ac cepted standard, but evidence supporting it comes from single dose stu dies performed before the advent of patient controlled analgesia (PCA) , We compared morphine and hydromorphone use with PCA in bone marrow t ransplantation patients who required opioids for the control of severe oral mucositis over several days or weeks. An exploratory analysis of clinical records from 102 patients (981 patient days) who used PCA op ioids for varying periods of up to 50 days suggested a morphine to hyd romorphone use ratio of 3:1. To clarify :his observation, we studied a subset of patients under matched conditions. During a 7 day window in which mean oral mucositis severity did not vary across drug use group s and pain scores did not vary over time, patients in both groups gave equal pain relief satisfaction scores. Thirty-six patients who used m orphine and 21 who used hydromorphone contributed data on pain, satisf action with pain control, and drug consumption, We observed an average morphine/hydromorphine ratio of 3:1. This differs markedly from histo rical single dose studies used in published dose equivalency recommend ations implying that other equivalency ratios in clinical use may be i nappropriate.