Articles: narcotic-antagonists.
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Comparative Study
Central poststroke pain and reduced opioid receptor binding within pain processing circuitries: a [11C]diprenorphine PET study.
Based on concepts that endogenous opioids participate in neural transmission of pain, the present study in central poststroke pain (CPSP) patients investigated changes in opioid receptor (OR) binding in neural structures centrally involved in the processing of pain. Five patients with central pain after lesions in the brain stem, thalamus or parietal cortex and twelve healthy volunteers underwent a [11C]diprenorphine positron emission tomography study. Binding potentials were calculated using a reference region model in all subjects. ⋯ Individual extracted binding values disclosed a reduced binding in these regions in all patients independent from the particular lesion site. The poststroke pain syndrome is associated with a characteristic pattern of reduced OR binding within the neural circuitry processing pain. It is suggested that an imbalance of excitatory-inhibitory mechanisms in certain brain structures, as evidenced in decreased [11C]diprenorphine binding, is one of the causes or the consequences of poststroke pain.
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Review
Clinical status of methylnaltrexone, a new agent to prevent and manage opioid-induced side effects.
Opioids are associated with a number of adverse effects, constipation being the most common long-term adverse effect in patients with advanced cancer. Significant progress has been made over the past several decades in understanding the mechanisms of action of opioid compounds; however, these advances have yielded few new treatments for the bowel dysfunction caused by opioids. Methylnaltrexone, the first peripheral opioid receptor antagonist and currently under clinical investigation, has the potential to prevent or treat opioid-induced peripherally mediated side effects, such as constipation, without interfering with analgesia. This article reviews existing clinical data on methylnaltrexone, focusing on the antagonism of opioid-induced adverse effects in the gut.
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Psychosomatic medicine · Mar 2004
Clinical Trial Controlled Clinical TrialSex differences in pain and hypothalamic-pituitary-adrenocortical responses to opioid blockade.
Sex differences in pain sensitivity and stress reactivity have been well documented. Little is known about the role of the endogenous opioid system in these differences. This study was conducted to compare adrenocortical, pain sensitivity, and blood pressure responses to opioid blockade using naltrexone in men and women. ⋯ Although men and women exhibited similar hormonal responses to opioid receptor blockade, women reported less pain and showed smaller blood pressure responses during CPT. Results suggest differential effects of the endogenous opioid system on pain perception and blood pressure in men and women.
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The relieving effects of electroacupuncture (EA) on mechanical allodynia and its mechanism related to the spinal opioid system were investigated in a rat model of neuropathic pain. To produce neuropathic pain in the tail, the right superior caudal trunk was resected between the S1 and S2 spinal nerves. Two weeks after the surgery, EA stimulation (2 or 100 Hz, 0.3 ms, 0.2-0.3 mA) was delivered to Zusanli (ST36) for 30 min. ⋯ All three opioid agonists also showed relieving effects on mechanical allodynia. However, nor-BNI could not block the EA effects on mechanical allodynia, whereas beta-FNA or naltrindole significantly blocked EA effects. These results suggest that the mu and delta, but not kappa, opioid receptors in the spinal cord of the rat, play important roles in mediating relieving effects on mechanical allodynia induced by 2 Hz EA.
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An increasing and serious heroin overdose problem in Oslo has mandated the increasing out-of-hospital use of naloxone administered by paramedics. The aim of this study was to determine the frequencies and characteristics of adverse events related to this out-of-hospital administration by paramedics. ⋯ Although adverse events were common among patients treated for opioid overdose in an out-of-hospital setting, serious complications were rare. Out-of-hospital naloxone treatment by paramedics seems to save several lives a year without a high risk of serious complications.