The journal of pain : official journal of the American Pain Society
-
Randomized Controlled Trial
Efficacy and safety of OPANA ER (oxymorphone extended release) for relief of moderate to severe chronic low back pain in opioid-experienced patients: a 12-week, randomized, double-blind, placebo-controlled study.
Opioid-experienced (N = 250) patients with chronic, moderate to severe low back pain (LBP) were converted from their prestudy opioid(s) to an approximately equianalgesic dose of OPANA ER (oxymorphone extended release). Patients continued slow titration, with 56% stabilized within 1 month to a dose of OPANA ER that reduced average pain to <40 mm on a visual analog scale with good tolerability. Stabilized patients (n = 143) were randomized to placebo or their stabilized dose of OPANA ER every 12 hours for a 12-week double-blind period. Pain intensity increased significantly more for patients randomized to placebo than for patients who continued their stabilized dose of OPANA ER; the increase from baseline (at randomization) to final visit was 31.6 mm for placebo versus 8.7 mm with OPANA ER (P < .0001). During double-blind treatment, placebo patients were approximately 8-fold more likely than OPANA ER patients to discontinue because of lack of efficacy (P < .001). Discontinuations as a result of adverse events were similar between groups, 10% with placebo and 11% with OPANA ER. Opioid-related adverse events included constipation (6%), somnolence (3%), and nausea (3%). Fifty-seven percent of opioid-experienced patients with chronic, moderate to severe LBP achieved a stable dose of OPANA ER that was efficacious and generally well-tolerated for up to 12 weeks. ⋯ In a 12-week, double-blind, randomized, placebo-controlled trial in opioid-experienced patients with chronic, moderate to severe LBP, OPANA ER provided efficacious, long-term analgesia and was generally well-tolerated. OPANA ER may provide clinicians with a new treatment option for patients experiencing suboptimal analgesic responses or poor tolerability with other opioids.
-
Comparative Study Clinical Trial
Symptom profiles differ in patients with neuropathic versus non-neuropathic pain.
The distinction between neuropathic and non-neuropathic pain reflects partially distinct mechanisms and patterns of treatment response. It was therefore hypothesized that patients with neuropathic and non-neuropathic pain have different profiles of symptoms and signs. To test this hypothesis, pain intensity, unpleasantness, quality, and spatial characteristics were examined in 618 patients with 1 of 3 peripheral neuropathic pain conditions (painful diabetic peripheral neuropathy, painful idiopathic sensory polyneuropathy, or postherpetic neuralgia), osteoarthritis pain, or low back pain. These assessments were conducted before treatment had begun in clinical trials of lidocaine patch 5% administered alone or with stable dosages of other analgesics. Patients with osteoarthritis pain and low back pain did not differ in their profile of pain quality and spatial characteristics and were combined to form a group of patients with non-neuropathic pain. In univariate analyses, patients with peripheral neuropathic pain reported significantly more intense hot, cold, sensitive, itchy, and surface pain and significantly less intense dull and deep pain than patients with non-neuropathic pain. In a multivariate analysis, the overall pattern of pain quality and spatial characteristics differed significantly between patients with neuropathic and non-neuropathic pain. In addition, specific pain quality and spatial characteristics improved the discrimination of patients with neuropathic and non-neuropathic pain in a logistic regression model that adjusted for demographic covariates and overall pain intensity and unpleasantness. ⋯ The results indicate that the distinction between neuropathic and non-neuropathic pain is reflected in different profiles of pain quality and spatial characteristics and suggest that the assessment of patterns of pain symptoms might contribute to the identification of distinct pathophysiologic mechanisms and the development of mechanism-based treatment approaches.
-
Although previous research suggests that preamputation pain is a risk factor for pain after amputation, little is known about the association between acute postsurgical pain and chronic amputation-related pain. The current prospective study examined the associations of preamputation pain and acute postamputation pain with chronic amputation-related pain. The sample consisted of patients with lower limb amputation (N = 57) who provided both preamputation and postamputation data during a 2-year study period. Preamputation pain intensity and duration were assessed before amputation; acute phantom limb pain (PLP) and residual limb pain (RLP) intensity were assessed on postsurgical days 4 and 5. Acute PLP intensity was the only significant independent predictor of chronic PLP intensity at 6 and 12 months after amputation, whereas preamputation pain intensity was the only significant predictor of chronic PLP intensity at 24 months. Similarly, acute RLP was found to be the best overall predictor of chronic RLP. Other variables (age, gender, level and etiology of amputation, amount of postsurgical pain medication, and duration of preamputation pain) were not associated with chronic pain. These results suggest that higher levels of pain either before or soon after amputation might help to identify individuals at greatest risk for chronic pain problems and most in need of early, intensive pain interventions. ⋯ This study suggests that both preamputation pain and acute pain soon after amputation might be associated with bothersome chronic pain. The results support further research on acute pain mechanisms and the effectiveness of early interventions aimed at preventing or managing amputation-related pain.
-
Activated glia are a source of substances known to enhance pain, including centrally synthesized prostaglandins. We have previously shown that microglia are activated in the spinal cord following peripheral formalin injection. In the present study, we investigated cyclooxygenase (COX-1 and COX-2) expression in the spinal cord using immunohistochemistry and Western blots in the formalin pain model, to further understand how spinal glia modulate pain processing. We show that both COX-1 and COX-2 are constitutively expressed in the spinal cord. Hind paw formalin injection increased COX-1 expression, beginning at 1 day after injection and lasting at least 2 weeks, the duration of experiments. The COX-2 expression changed considerably less, with a significant increase of COX-2 protein level only observed at 2 h after injection. Double labeling studies showed that COX-1 was expressed in microglia and COX-2 was expressed in neurons. These data indicate that both COX-1 and COX-2 are increased in the spinal cord following formalin injection, but the time course and cellular sources are different, suggesting that both COX-1 (longer time points) and COX-2 (very short time points) may be involved in spinal modulation in the formalin pain model. Our study also suggests that spinal microglial activation may play a role in long-term hyperalgesia through the increased expression of COX-1. ⋯ This article reports that COX-1 expression by microglia is increased in the spinal cord after peripheral formalin injection into the rat hind paw. This result could potentially help clinicians understand how COX-1 may be involved in pain processing and the role microglial activation plays in pain mechanisms.
-
Certain parental behaviors are associated with child coping and others with child distress when children undergo painful medical procedures. The finding that parental reassurance is linked with increases in child distress is perplexing and counterintuitive. The objective of the present study was to provide a detailed linguistic description of the speech functions and tones parents use when reassuring during painful medical procedures. Videotapes of 28 5-year-old children (12 boys, 16 girls) receiving immunizations who were accompanied by their parents were examined. The majority of reassuring verbalizations were statements; minor clauses (eg, "okay") were the next most frequent type of utterance. Half of the reassuring verbalizations were spoken with a falling tone, which is indicative of speaker certainty and protectiveness. This detailed linguistic approach offers new insights into the qualities of parental reassurance during painful medical procedures. Further research is needed to elucidate the complex interactions of tone, speech function, and reassurance and their effects on child distress. ⋯ This article presents a detailed description of parental reassurance during pediatric immunizations. The description of the linguistic qualities of reassurance can help inform future research examining which characteristics of reassurance are associated with child distress and can help guide parental behavior during immunizations.