Toxicity and/or insufficient analgesia by opioid therapy: risk factors andthe impact of changing the opioid. A retrospective analysis of 273 patients observed at a single center

The charts of 273 cancer patients were retrospectively analyzed in order (1 ) to evaluate the frequency of opioid change (OCH) when adjuvants (antiemet ics/laxatives) were administered on a regular basis and co-analgesic medica tion as indicated by the specific type of pain, (2) to define risk factors for the request of OCH, and (3) to reveal settings in which OCH may not be recommended as a first-line therapeutic intervention. Opioids used included morphine, fentanyl, 1-methadone, and buprenorphine. Out of 273 patients, 1 03 changed opioids at least once, with a success rate of 65%. The indicatio ns for the OCH were insufficient analgesia in 43%, intolerable side effects in 20%, both in 15%, and other reasons in 22% of patients. The frequency o f OCH was not influenced by the routine use of adjuvants or co-analgesics e xcept corticosteroids, which raises queries about the concept of an opioid- sparing effect of co-analgesics. The occurrence of intolerable side effects is thought not to be dose dependent so much as to reflect differences in t he individual tolerability of a distinct opioid for whatever reason (geneti cally fixed or individually acquired pharmacodynamic or kinetic properties) . Moreover, there was strong evidence for the existence of an unpredictable and incomplete cross-tolerance between opioids, which meant careful titrat ion of the new opioid was required after OCH. The overall frequency of OCH was similar to that observed in previous studies in spite of the documented addition of adjuvants and co-analgesics. This retrospective study supports the notion that opioid rotation must be retained as an essential therapeut ic option even with optimized adjuvant and co-analgesic regimens.