Analgesic tolerance without demonstrable opioid-induced hyperalgesia: A double-blinded, randomized, placebo-controlled trial of sustained-release morphine for treatment of chronic nonradicular low-back pain

• Published in: Pain (Amsterdam) Vol. 153; no. 8; pp. 1583 - 1592
• Main Authors: Chu, Larry F., D’Arcy, Nicole, Brady, Caitlin, Zamora, Abigail Kathleen, Young, Chelsea Anne, Kim, Julie Eunwoo, Clemenson, Anna Marie, Angst, Martin S., Clark, J. David
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA Elsevier B.V 01.08.2012; Elsevier
• Subjects: Adolescent; Adult; Aged; Analgesic tolerance; Analgesics; Biological and medical sciences; Chronic opioid therapy; Delayed-Action Preparations - adverse effects; Delayed-Action Preparations - therapeutic use; Double-Blind Method; Drug Tolerance; Female; Humans; Hyperalgesia - chemically induced; Hyperalgesia - diagnosis; Low Back Pain - complications; Low Back Pain - diagnosis; Low Back Pain - drug therapy; Low-back pain; Male; Medical sciences; Middle Aged; Morphine - adverse effects; Morphine - therapeutic use; Nervous system (semeiology, syndromes); Nervous system as a whole; Neurology; Neuropharmacology; Nonradicular; Opioid-induced hyperalgesia; Opioid-Related Disorders - diagnosis; Opioid-Related Disorders - etiology; Pain Measurement - drug effects; Pharmacology. Drug treatments; Placebo Effect; Treatment Outcome; Young Adult; Analgesic tolerance; Opioid-induced hyperalgesia; Low-back pain; Nonradicular; Chronic opioid therapy; Human; Lumbar spine; Low back pain; Diseases of the osteoarticular system; Tolerance; Morphine; Spine disease; Long term; Hyperalgesia; Prospective; Analgesia; Analgesic; Pain; Treatment; Placebo; Rachialgia; Release
• ISSN: 0304-3959; 1872-6623
• DOI: 10.1016/j.pain.2012.02.028

After 1month of oral morphine therapy, chronic low-back pain patients developed tolerance but not opioid-induced hyperalgesia. Improvements in pain and functional ability were observed. Although often successful in acute settings, long-term use of opioid pain medications may be accompanied by waning levels of analgesic response not readily attributable to advancing underlying disease, necessitating dose escalation to attain pain relief. Analgesic tolerance, and more recently opioid-induced hyperalgesia, have been invoked to explain such declines in opioid effectiveness over time. Because both phenomena result in inadequate analgesia, they are difficult to distinguish in a clinical setting. Patients with otherwise uncomplicated low-back pain were titrated to comfort or dose-limiting side effects in a prospective, randomized, double-blind, placebo-controlled clinical trial using sustained-release morphine or weight-matched placebo capsules for 1month. A total of 103 patients completed the study, with an average end titration dose of 78mgmorphine/d. After 1month, the morphine-treated patients developed tolerance to the analgesic effects of remifentanil, but did not develop opioid-induced hyperalgesia. On average, these patients experienced a 42% reduction in analgesic potency. The morphine-treated patients experienced clinically relevant improvements in pain relief, as shown by a 44% reduction in average visual analogue scale pain levels and a 31% improvement in functional ability. The differences in visual analogue scale pain levels (P=.003) and self-reported disability (P=.03) between both treatment groups were statistically significant. After 1month of oral morphine therapy, patients with chronic low-back pain developed tolerance but not opioid-induced hyperalgesia. Improvements in pain and functional ability were observed.