Challenging equipotency calculation for hydromorphone after long-term intravenous application

In advanced stages, most cancer patients suffer from pain which can usually be well controlled following the World Health Organization (WHO) level scheme. While the majority of patients report adequate pain relief by strong opioids (WHO III), some require an opioid rotation. Despite the existence of conversion tables, these rotations mea lead to inadequate pain control or life threatening events. Here, we report about a patient with urothelial cell carcinoma presenting in our Department of Pain Medicine with massive pain aggravation up to NRS values of 10/10 despite administration of the highest dose of intravenously applied hydromorphone. After a small single dose of the far less potent opioid piritramide with exceptionally good response, we conducted a stepwise opioid rotation from hydromorphone to piritramide within one week without any signs of abstinence or withdrawal. After the opioid rotation, we discharged the patient nearly free of pain with piritramide doses far less than equianalgesic dose tables would have recommended. Our report impressively points out that even after long-term intravenous application of highly potent opioids, new titrations are necessary for rotation to avoid overdosage and discusses several mechanisms underlying individual response to different opioids.