Oxycodone First-Line, but Costlier, Alternative to Morphine for Adult Cancer Pain
NEW YORK (Reuters Health) - For adults with cancer-related pain, oxycodone can be used as an alternative to morphine, a new systematic review suggests.
"We found low-quality evidence that oxycodone offers similar levels of cancer pain relief and adverse events to other strong opioids including morphine, which is commonly considered the gold standard strong opioid," lead author Dr. Mia Schmidt-Hansen of the Royal College of Obstetricians and Gynaecologists in London, UK, and her coauthors write in BMJ Supportive & Palliative Care, online January 13.
"Our conclusions are consistent with other reviews and suggest that oxycodone can be used first line as an alternative to morphine. However, because it is cheaper, morphine generally remains the first-line opioid of choice," they write.
Dr. Schmidt-Hansen and colleagues searched the cancer-pain literature through November 2016 and ultimately analyzed data from 23 randomized controlled trials involving 2,144 patients with oxycodone efficacy data and 2,363 with safety data.
Meta-analyses revealed no significant differences in pain intensity or adverse events between controlled-release (CR) and immediate-release (IR) oxycodone but showed significantly better pain relief after treatment with CR morphine than with CR oxycodone. Because this effect did not persist in sensitivity analyses, the authors do not consider it to be important.
With respect to adverse events, hallucinations were significantly less common with CR oxycodone (4%) than CR morphine (7.8%), but given the low quality of evidence, the authors advise caution in interpreting this difference.
More patients on CR oxycodone than CR morphine experienced myoclonus, but the two drugs did not differ in causing drowsiness or confusion.
Studies that compared various formulations of oxycodone or that compared it to alternative opioids found no clear superiority or inferiority of the drug for pain relief or adverse events, but the authors note that this evidence was limited by the risk of bias and low event rates.
The authors also acknowledge the substantial overall dropout rate (19%) among the studies they analyzed.
Dr. David J. Tauben, chief of the Division of Pain Medicine at the University of Washington in Seattle, told Reuters Health by email, "It is noteworthy that immediate release relieved pain as well as controlled-release opioids for cancer-related pain. This is newsworthy and does add to the many important reconsiderations about how best to improve effective and safe use of opioids in the treatment of pain."
"Cancer-related pain (including active tumor-related tissue damage; and consequences of cancer-related surgery, chemotherapy, and radiation treatments) is a different condition than non-cancer chronic pain, and the use of opioids for cancer-related pain treatment has a more clearly established clinical basis for the use of CR opioids, even at higher doses than now considered effective or safe for non-cancer pain," said Dr. Tauben, who was not involved in the study.
"The conclusions inferentially support our own clinical observations at the University of Washington that IR opioids appear as effective and may be safer than CR opioids for most patients when prescribed for chronic, non-cancer pain conditions," he noted. "This is primarily due to the fact that IR opioids are most often prescribed at a lower total daily dose overall, since CR opioid formulations contain 2 to 8 times the opioid dosage of most used IR formulations."
"We recommend IR over CR whenever possible for non-cancer pain treatment, and now we do have evidence to support this approach when prescribing opioids for cancer pain. IR opioids hypothetically offer other potential 'chemical' (pharmacological) and clinical (patient-related) advantages compared to CR opioids," Dr. Tauben explained. "Pharmacologically, IRs may produce less tolerance due to reduced circulating drug levels at end of dose intervals, compared to CR opioids that are designed to deliver a constant circulating drug level around the clock."
Dr. Tauben added that on-demand IR opioid dosing allows some patients to skip doses whenever their pain diminishes, thereby reducing their total daily dosage.
"A similar analysis that compares IR and CR opioid treatment outcomes in chronic non-cancer pain would be an important contribution to the science and art of pain medicine," he recommended.
Dr. Schmidt-Hansen did not respond to requests for comment.
BMJ Support Palliat Care 2018.