Pain
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Case Reports Randomized Controlled Trial Clinical Trial
Ketamine as an adjunct to morphine in the treatment of pain.
A double-blind multidose trial of the addition of ketamine (0-40 mg, i.m., 8 times per day) to intramuscular morphine therapy was undertaken in a 61-year-old man with chronic back pain related to osteoporosis who had received inadequate pain relief from anterior interbody fusion, dorsal column stimulation and morphine alone. The patient reported only mild side effects. ⋯ In addition, the amount of morphine used by the patient was significantly reduced as the ketamine dose increased. This patient experienced substantial benefit from the addition of ketamine to intramuscular morphine therapy.
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Research has indicated that the way individuals cope with pain may influence pain, and physical and psychological adjustment. The present study assessed the relationship between coping strategy use and adjustment in amputees with phantom limb pain (PLP). Coping strategies were measured using the Coping Strategies Questionnaire (CSQ) and their relationship with adjustment was examined using both composite scores and individual strategy scores. ⋯ Catastrophizing also explained a large proportion of the variance in physical and psychosocial dysfunction (11% and 22%), while hoping or praying strategies accounted for only a small proportion of the variance in physical dysfunction (3%), and re-interpreting pain sensations accounted for a small proportion of the variance in psychosocial dysfunction (3%). The findings in this study have important clinical implications in that coping strategy use was associated with increased, rather than decreased, levels of pain and disability. However, since the reported use of coping strategies in the present study was low, further research, perhaps utilizing other measures of coping, is required to clarify these findings.
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Antinociceptive tolerance to morphine (MOR) was induced in groups of Sprague-Dawley rats receiving continuous intravenous infusions of morphine sulphate administered by 3 different MOR dosing regimes. At appropriate intervals throughout each infusion period, antinociceptive testing was performed using the tail-flick latency test and blood samples were collected. Groups of saline (SAL)-infused control rats also underwent antinociceptive testing and blood sample collection. ⋯ In addition, a poor relationship was observed between %MPE and the mean plasma MOR concentration, possibly due to the confounding presence of M3G in all samples. Thus, we may conclude from this study in Sprague-Dawley rats that irrespective of the rate of antinociceptive tolerance development, the level of antinociception achievable appears to be highly inversely correlated with the mean [M3G]/[MOR] plasma molar concentration ratio and poorly correlated with the plasma MOR concentration, consistent with the notion that it is perhaps the balance between the excitatory effects of M3G and the inhibitory effects of MOR at the functional level which is the important determinant. Further research is required in carefully conducted studies in cancer patients to evaluate the possible contribution of the MOR metabolites, M3G and morphine-6-glucuronide (MbG), to increasing dosing requirements of MOR.(ABSTRACT TRUNCATED AT 400 WORDS)
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Recent evidence suggests that hyperalgesia and morphine tolerance, two seemingly unrelated phenomena, have in common certain neural substrates such as activation of the N-methyl-D-aspartate (NMDA) receptor and the subsequent intracellular activation of protein kinase C and nitric oxide. Should common cellular elements be involved in hyperalgesia and morphine tolerance, these cellular and intracellular commonalities might be expected to result in interactions between these two phenomena. Indeed, our previous studies have shown that thermal hyperalgesia develops when animals are made tolerant to the antinociceptive effects of morphine. ⋯ In addition, once daily treatment with 10 nmol MK-801 from D2 to D7 after nerve ligation prevented both the development of thermal hyperalgesia and the rightward shift of the morphine antinociceptive dose-response curve on D8. The results indicate that the antinociceptive effects of morphine are reduced in nerve-injured rats in the absence of daily exposure to morphine and that the NMDA receptor activation may have a critical role in mechanisms of this phenomenon. These data provide further evidence indicating that interactions do occur between neural mechanisms underlying thermal hyperalgesia and morphine tolerance.
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In a rat model of artificial ureteral calculosis, the aim of the study was to characterize the behavioural manifestations of direct visceral pain and to evaluate the relationship between number, duration and complexity of the visceral episodes and the extent of referred lumbar muscular hyperalgesia. As evidenced by non-stop video-tape recordings over 4-14 days, almost 98% of stone-implanted rats showed episodes similar to the writhing behaviour characteristic of noxious visceral stimulation in animals. From one rat to another, these episodes varied from very few (1-3) to a very high number (+/- 60), lasted a few minutes to over 45 min and were of variable complexity, as evaluated via an arbitrary scale on the basis of the combination of movements. ⋯ Stone-implanted rats displaying visceral episodes also showed hyperalgesia of the ipsilateral oblique musculature, as evidenced by a decrease in the vocalization threshold to electrical muscle stimulation, which was maximum on the first 3-4 days after implantation but lasted up to 10 days. The visceral episodes and the muscle hyperalgesia showed a strict relationship of interdependence: a significant, direct linear correlation was found between number and duration of episodes and tendency to also develop a contralateral muscle hyperalgesia. By applying the results of the study to the interpretation of human pathology, referred lumbar muscle hyperalgesia from ureteral calculosis would appear to be a strict function of the colic pain experienced.