Pain
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The characteristics and impact of pain were evaluated in a prospective cross-sectional survey of 438 ambulatory AIDS patients recruited from health care facilities in New York City. More than 60% of the patients reported 'frequent or persistent pain' during the 2 wks preceding the study. Patients with pain reported an average of 2.5 different pains. ⋯ Presence of pain and increasing pain intensity were significantly associated with greater impairment in functional ability (Karnofsky Performance Status, BPI functional interference index) and physical symptom distress (Memorial Symptom Assessment Scale). Results demonstrate high levels of pain and pain-related functional impairment among patients with AIDS. The presence and intensity of pain are associated with more advanced HIV disease and pain intensity is also associated with demographic factors (gender, race).
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Compounds related to capsaicin and its ultrapotent analog, resiniferatoxin (RTX), collectively referred to as vanilloids, interact at a specific membrane recognition site (vanilloid receptor), expressed almost exclusively by primary sensory neurons involved in nociception and neurogenic inflammation. Desensitization to vanilloids is a promising therapeutic approach to mitigate neuropathic pain and pathological conditions (e.g. vasomotor rhinitis) in which neuropeptides released from primary sensory neurons play a major role. Capsaicin-containing preparations are already commercially available for these purposes. ⋯ We further focus on ligand-induced messenger plasticity, a recently discovered mechanism underlying the analgesic actions of vanilloids. Lastly, we give a brief overview of the current clinical uses of vanilloids and their future therapeutic potential. The possibility is raised that vanilloid receptor subtype-specific drugs may be synthesized, devoid of the undesirable side-effects of capsaicin.
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N-Methyl-D-aspartate (NMDA) receptor antagonists have been shown to block the development of antinociceptive tolerance to morphine. Assessment of the effects of NMDA antagonists on development of antinociceptive tolerance to selective opioid mu (mu) and delta (delta) agonists, however, has not been reported. In these experiments, selective mu and delta receptor agonists, and morphine, were repeatedly administered to mice either supraspinally (i.c.v.) or systemically (s.c.), alone or after pretreatment with systemic NMDA antagonists. ⋯ Further, MK801 pretreatment also did not affect the development of tolerance to the antinociception resulting from a cold-water swim-stress episode, previously shown to be a delta-opioid mediated effect. These data lead to the suggestion that the mechanisms of tolerance to receptor selective mu and delta opioids may be regulated differently from those associated with morphine. Additionally, these findings emphasize that conclusions reached with studies employing morphine cannot always be extended to 'opiates' in general.
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The objective of this study was to review the effectiveness and safety of antidepressants in neuropathic pain. In a systematic review of randomised controlled trials, the main outcomes were global judgements, pain relief or fall in pain intensity which approximated to more than 50% pain relief, and information about minor and major adverse effects. Dichotomous data for effectiveness and adverse effects were analysed using odds ratio and number needed-to-treat (NNT) methods. ⋯ Compared with placebo, of 100 patients with neuropathic pain who are given antidepressants, 30 will obtain more than 50% pain relief, 30 will have minor adverse reactions and four will have to stop treatment because of major adverse effects. With very similar results for anticonvulsants it is still unclear which drug class should be first choice. Treatment would be improved if we could harness the dramatic improvement seen on placebo in some of the trials.
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Clinical Trial
Sequential daily relations of sleep, pain intensity, and attention to pain among women with fibromyalgia.
Fifty women with fibromyalgia syndrome (FS) recorded their sleep quality, pain intensity, and attention to pain for 30 days, using palm-top computers programmed as electronic interviewers. They described their previous night's sleep quality within one-half hour of awakening each day, and at randomly selected times in the morning, afternoon, and evening rated their present pain in 14 regions and attention to pain during the last 30 min. We analyzed the 30-day aggregates cross-sectionally at the across-persons level and the pooled data set of 1500 person-days at the within-persons level after adjusting for between-persons variation and autocorrelation. ⋯ A night of poorer sleep was followed by a significantly more painful day, and a more painful day was followed by a night of poorer sleep. Pain attention and sleep were unrelated at the across-persons level of analysis. But there was a significant bi-directional within-person association between pain attention and sleep quality that was not explained by changes in pain intensity.