Conversion to oral controlled-release oxycodone from intravenous opioid analgesic in the postoperative setting.

OBJECTIVE This study assessed conversion factors utilized by physicians to transfer postoperative patients from intravenous opioids to oral controlled-release (CR) oxycodone and the subsequent analgesic effectiveness. DESIGN This was a multicenter, open-label, usual-use study of 189 hospitalized postoperative patients receiving opioid (usually morphine) intravenous patient-controlled analgesia (IV PCA) for at least 12 to 24 hours post-procedure. Patients who were tolerant of oral medications and without signs of paralytic ileus were converted to oral CR oxycodone, given every 12 hours for up to 7 days. RESULTS The mean (+/-SE) conversion factor used to convert IV PCA morphine to CR oxycodone was 1.2 +/- 0.1 (N=159). The initial CR oxycodone doses, based on individual conversion factors from IV PCA morphine, produced significant reductions in pain intensity (scores <or=4) within 6 hours after the initial dose. The mean +/- SE initial dose of CR oxycodone, for patients converted from IV PCA morphine, was 27 +/- 1 mg; that for all patients was 29 +/- 2 mg. Pain at the end of the first 12 hours was controlled with these initial doses. The most common adverse events were constipation, nausea, and pruritus. CONCLUSIONS Administered at least 12 hours following abdominal, orthopedic, or gynecologic surgery, an initial oral CR oxycodone dose calculated by multiplying the amount of IV morphine used in the previous 24 hours (immediate postoperative period) by a conversion factor of 1.2, on average, provided adequate pain control during the subsequent 12-hour dosing interval and for a maximum of 7 days. Adverse events were consistent with opioid side effects.