Pain
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Cyclooxygenase-2 (COX-2) activity in the spinal cord plays a key role in sensitization to sensory stimuli during acute inflammation. In contrast, intrathecal administration of COX-2 specific inhibitors has minimal analgesic effects in an incisional model of postoperative pain. We investigated the role of COX isoforms in this model by examining the expression of COX-1 and the effect of intrathecal COX inhibitors. ⋯ Ketorolac and SC-560 dose-dependently increased withdrawal threshold in this model, but NS-398 had no effect. These results suggest that COX-1 plays an important role in spinal cord pain processing and sensitization after surgery. Increased COX-1 activity could precede the up-regulation of COX-1 protein, and spinally administered specific COX-1 inhibitors may be useful to treat postoperative pain.
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Randomized Controlled Trial Multicenter Study Comparative Study Clinical Trial
Tramadol in post-herpetic neuralgia: a randomized, double-blind, placebo-controlled trial.
The efficacy and safety of sustained-release tramadol compared to placebo in the treatment of post-herpetic neuralgia were evaluated in a multicenter, randomized, double-blind, parallel-group study in 127 outpatients. Treatment was administrated for 6 weeks. The dose of tramadol could be increased from 100 mg/day to 400 mg/day (300 mg/day in patients more than 75 years old). ⋯ Tramadol was administered at an average dosage of 275.5 (89.7) mg/day after a 1-week dose-adaptation period. Tramadol was well tolerated. No notable difference appeared between groups either in the percentage of patients with treatment-associated adverse events (TAAE) (29.7% in the tramadol group and 31.8% in the placebo group) or in the total number of TAAE (31 in the tramadol group and 28 in the placebo group).
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Randomized Controlled Trial Clinical Trial
Injection of nerve growth factor into human masseter muscle evokes long-lasting mechanical allodynia and hyperalgesia.
Nerve growth factor (NGF) is a neurotrophic protein with a pivotal role in development and maintenance of the nervous system on one side and inflammatory and neuropathic pain states on the other. NGF causes clear signs of behavioral hyperalgesia in animal models and following intradermal and systemic administration in humans. The present double-blinded, placebo-controlled study was designed to test quantitatively the effect and duration (1h, 1, 7, 14, 21 and 28 days) of NGF (5 microg in 0.2 ml) injected into the masseter muscle. ⋯ Systemic adverse effects were noted in one subject who reported fever and slight discomfort about 8h after the NGF injection. In conclusion, this is the first study to show that injection of NGF into the human masseter muscle causes local signs of mechanical allodynia and hyperalgesia that persist for at least 7 days as well as pain during strenuous jaw movement. The present pain model is safe and may be used to gain further insight into the neurobiological mechanisms of muscle pain and sensitization.
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Randomized Controlled Trial Comparative Study Clinical Trial
Intra-articular (IA) catheter administration of postoperative analgesics. A new trial design allows evaluation of baseline pain, demonstrates large variation in need of analgesics, and finds no analgesic effect of IA ketamine compared with IA saline.
All previous studies of intra-articular (IA) analgesic drugs for postarthroscopy pain have administered test-drugs at the end of the arthroscopic procedure, before any baseline pain could be assessed. Assay sensitivity has often not been documented or has been assumed to be present if a placebo control group had significant pain during the observation period. We present an improved study design employing an IA catheter for test-drug administration only in patients with moderate-to-severe baseline pain within 2h postoperatively. ⋯ The new method for IA analgesic trials solves the problem with undesirable inclusion of patients with no or mild pain. We observed rapid onset and significant pain relief after IA injection of 10 ml saline with or without ketamine 10mg, but no difference between these two test medications. Intra-muscular ketamine 10mg showed significantly better early pain relief, global evaluation, and longer time to rescue analgesic, compared with IA ketamine 10mg.
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Comparative Study
Long term effects of oral sustained release morphine on neuropsychological performance in patients with chronic non-cancer pain.
Morphine is increasingly used in patients with chronic non-cancer pain, but a major concern associated with chronic use relates to possible cognitive side-effects. The aim of this long-term prospective study was to evaluate the cognitive impact of oral sustained release morphine in patients with non-cancer pain. A battery of neuropsychological tests to explore attention, psychomotor speed and memory was administered. ⋯ Morphine induced persisting effects on pain, and to a lesser extent on quality of life and mood. The visual analog scale score for side-effects increased at 12 months and essentially consisted of gastrointestinal disorders. This study demonstrates that 12 months treatment with oral morphine does not disrupt cognitive functioning in patients with chronic non-cancer pain and instead results in moderate improvement of some aspects of cognitive functioning, as a consequence of the pain relief and concomitant improvement of well-being and mood.