Long- and Short-Acting Opioids Equally Good for Chronic Non-Malignant Pain
By Lorraine L. Janeczko
NEW YORK - Many guidelines recommend long-acting over short-acting opioids for chronic non-malignant pain, but new research suggests both are equally effective.
Long-acting dihydrocodeine was not better for any of the trial's outcomes, researchers wrote December 16 in Pain.
"There is no difference in stability of pain intensity, and in worst, least or mean pain intensity between short- and long-acting dihydrocodeine. There is also no difference in quality of life, depression and quality of sleep between the formulations," lead author Dr. Line Pedersen, from Norwegian University of Science and Technology in Trondheim, wrote in an email to Reuters Health.
Experts who commented on the study for Reuters Health pointed out some methodological weaknesses, however, and one warned that participants' conditions might not have warranted treatment with opioids in the first place.
Dr. Pedersen and colleagues conducted a randomized, double-blind, double-dummy eight-week comparison trial of the two formulations.
They included 60 patients ages 18 to 75 with chronic non-malignant pain who were referred to a multidisciplinary pain clinic in Norway. All participants had taken codeine-paracetamol (acetaminophen) tablets before the trial.
Because dihydrocodeine is not commercially available in Norway, the authors assumed that all patients would be naive to it, and no patients stated that they had taken dihydrocodeine.
One group received active long-acting dihydrocodeine every eight to 12 hours and a placebo four times daily, while the other received short-acting dihydrocodeine four to six times daily and a long-acting dihydrocodeine-placebo every 12 hours. Paracetamol was added at set times for both groups four to six times each day, and the paracetamol tablets were taken together with the short-acting dihydrocodeine or placebo.
Taking extra paracetamol, opioids, or non-steroidal anti-inflammatory drugs as needed was not permitted.
Of the 60 patients included in the study, 58 were randomized; 18 in the long-acting group and 21 in the short-acting group completed the trial. Patients who completed and those who dropped out were similar in age, pain scores, and depression scores. Between treatment arms, reasons for withdrawal were also similar: adverse events, lack of efficacy, or both.
After the trial, before the blinding was opened, all participants were asked about their medication preference. Of the 18 patients in the long-acting group, nine (50%) preferred the study drug over codeine, five (27.8%) preferred pre-trial codeine treatment, and four (22.2%) had no preference.
Of the 21 patients in the short-acting group, 13 (61.9%) preferred the study drug over codeine, three (14.3%) preferred codeine, and five (23.8%) had no preference.
Dr. Pedersen cautioned that "there is no high quality research assessing the different risks of addiction between long- and short-acting opioids, and both formulations should be used with equal caution in chronic non-malignant pain."
"Because there is scant long-term data about the long-term effects of opioids in chronic pain, clinicians should be equally cautious when prescribing these potent drugs. There is no evidence that long-acting opioids are safer or more efficacious than short-acting opioids," Dr. Pedersen added.
Dr. Gary M. Franklin, from the University of Washington in Seattle, also expressed caution. "The distribution of baseline factors across the two treatment groups showed substantial differences, indicating that the randomization process was likely flawed. Taken together, these methodological flaws would downgrade this randomized trial to a level III study, with a high risk of bias," he told Reuters Health in an email.
"Strikingly, and similar to other randomized trials of opioids for this condition, there was a very high drop-out rate (37%), mostly due to lack of efficacy or adverse events. Missing data either at baseline or at the eight-week follow up were seen in over 25% of patients," he said.
Dr. Franklin, who was not involved in the study, added, "Many of the conditions for which patients were receiving opioids chronically are likely not good candidates for treatment with opioids (fibromyalgia, low back pain), and such treatment could place these patients at high risk for adverse outcome, dependence, or addiction."
"This article assumes that opioids SHOULD be used in these patients; however, current data suggest that most of these patients should probably not be receiving opioids chronically unless using opioids brings about SUBSTANTIAL improvement IN PAIN AND FUNCTION," he said. "The new FDA labeling on long acting-sustained release opioids recommends against their use in all but the most severe pain."
SOURCE: https://bit.ly/19QWS1s
Pain 2013.
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