Pain
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Randomized Controlled Trial Clinical Trial
Characterisation of capsaicin-induced mechanical hyperalgesia as a marker for altered nociceptive processing in patients with rheumatoid arthritis.
Rheumatoid arthritis (RA) is characterised by pain and tenderness not only over inflamed or damaged joints, but also over apparently normal tissues. Experimental models suggest that these features results from changes of sensitivity within both peripheral and central neurones, but direct evidence from human disease is lacking. At present, most clinical studies have evaluated overall pain experience rather than activity within components of the nociceptive pathway. ⋯ Peripheral sensory activity over the forearms of rheumatoid patients has previously been shown to be normal and the results suggest the presence of enhanced central mechanisms in this disorder. The correlation between capsaicin-induced hyperalgesia and joint tenderness in the RA patients implies that joint symptoms arise partially as a result of central, and not exclusively peripheral, factors. The study supports the use of capsaicin-based techniques to explore nociceptive mechanisms in clinical disorders characterised by chronic pain.
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Review
Pain relief from intra-articular morphine after knee surgery: a qualitative systematic review.
Reduction of postoperative pain by injecting opioid into the knee joint is believed to support the hypothesis of peripheral opioid receptor activation in inflammation. The study design consisted of a systematic review of randomised controlled trials (RCTs). Main outcomes were pain intensity and the use of supplementary analgesics. ⋯ We conclude that intra-articular morphine may have some effect in reducing postoperative pain intensity and consumption of analgesics. These studies had significant problems in design, data collection, statistical analysis and reporting. Trials of better methodological quality are needed for a conclusive answer that intra-articular morphine is analgesic, and that any analgesia produced is clinically useful.
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Randomized Controlled Trial Clinical Trial
Benzodiazepine mediated antagonism of opioid analgesia.
Activation of supraspinal gamma-aminobutyric acid-A (GABAA) receptors is known to result in antagonism of opioid analgesia. Since benzodiazepines enhance the action of GABA at GABAA receptors, we hypothesized that administration of these agents for preoperative sedation might antagonize the analgesic effects of opioids administered postoperatively. If so, then administration of the benzodiazepine antagonist flumazenil should enhance postoperative morphine analgesia. ⋯ Participants receiving flumazenil reported significantly less post-discharge nausea and used significantly less ibuprofen. Since post-discharge pain levels were not significantly different, these results suggest that the patients receiving flumazenil required less analgesic medication to achieve a comparable level of pain control. In summary, our results indicate that the benzodiazepine antagonist flumazenil enhances morphine analgesia and decreases post-discharge side-effects as well as post-discharge need for analgesic medication.
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Clinical Trial Controlled Clinical Trial
Hydromorphone analgesia after intravenous bolus administration.
This study investigated the analgesic effects of three intravenous bolus doses of hydromorphone (10, 20, 40 micrograms/kg) on experimental pain measures in normal humans. Ten healthy male volunteers participated in four study sessions, one for each of the hydromorphone doses as well as a placebo (saline). They received the four treatments in counterbalanced order under double-blind conditions and with study days at least 1 week apart. ⋯ Although the peak effect was poorly defined, the onset of analgesia was rapid, within 5 min, and maximum analgesic effect was seen between 10 and 20 min after maximum plasma hydromorphone concentration. However, within sessions we found a poor correspondence between hydromorphone plasma concentration and effect. Compared to pain report data from other human studies done in our laboratory, hydromorphone has a shorter time to peak effect compared to morphine, and overall, hydromorphone hydrochloride is approximately five times as potent as morphine sulfate on a milligram basis.