Pain
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It has recently been shown that O-demethylation of the opioid drug codeine to morphine depends on the sparteine/debrisoquine oxygenase (CYP2D6) which in man exhibits genetic polymorphism. Morphine may be an endogenously formed substance in mammalians. Therefore, it may be hypothesized that the final step in an endogenous synthesis of morphine from codeine also depends on CYP2D6. ⋯ However, for the cold pressor test, peak pain ratings and area under the pain rating-time curve during 2 min were significantly higher in poor than in extensive metabolisers (P = 0.0024 and 0.044). Furthermore, a substantially higher fraction of poor metabolisers prematurely withdrew their hand from the ice water during the cold pressor test due to intolerable pain (32 vs. 18%, P = 0.0545). We conclude that poor metabolisers of sparteine may be less tolerant to tonic pain than extensive metabolisers, and we hypothesize that this may be related to an inherited defect in endogenous synthesis of morphine via CYP2D6 in the brain.
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This study evaluated the antinociceptive effects of systemically administered selective opioid agonists of mu (DAMGO), delta (BUBU) and kappa (U 69593) receptors on the vocalization threshold to paw pressure in a rat model of peripheral unilateral mononeuropathy produced by loose ligatures around the common sciatic nerve. DAMGO (0.5-2 mg/kg), BUBU (1.5-6 mg/kg) and U 69593 (0.75-3 mg/kg) injected intravenously (i.v.) produced a potent long-lasting antinociceptive effect on both hind paws. ⋯ The present data clearly show that an acute i.v. injection of these selective opioid agonists induces potent antinociceptive effects in a rat model of peripheral neuropathy. These data are discussed with regard to the classical view that there is opioid resistance in neuropathic pain.
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Randomized Controlled Trial Clinical Trial
The relationship between children's coping styles and psychological interventions for cold pressor pain.
This study examined the hypothesis that matching pain management interventions to children's preferred coping methods would increase pain tolerance and decrease self-reported pain during the cold pressor pain paradigm. Children aged 8-10 years were classified as 'attenders' (focusing on the stimulus) or 'distractors' (focusing away from the stimulus) based upon their spontaneous coping responses during a baseline exposure to the cold pressor. Children were then randomly assigned to 1 of 3 intervention conditions (sensory focusing, imagery, or no intervention) and completed the cold pressor procedure again 2 weeks later. ⋯ Although pain ratings tended to be lower for distractors using imagery, the significant interaction resulted from an increase in ratings for the distractors using sensory focusing (i.e., a 'mismatched' intervention). Results suggest that, for distractors, interventions that are consistent with natural coping methods are most effective in enhancing abilities to cope with pain, while a mismatched intervention reduces coping abilities. The findings also suggest further study regarding how to provide effective pain intervention with attenders, since neither intervention enhanced coping in this group.
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Pain ratings and pain-related cerebral potentials in response to noxious stimuli were investigated under hypnotic hypo- or hyperalgesia. Out of a sample of 50 subjects the 10 most highly hypnotizable were selected using the Stanford Hypnotic Susceptibility Scale. Phasic pain was induced by brief electrical stimuli intracutaneously applied to the subject's left middle finger. ⋯ In contrast, the amplitudes of the late somatosensory potentials evoked by the pain-inducing stimuli were not modified in either of the suggestive states. Furthermore, no effects of hypnosis were found on AEPs and on the power spectra of the spontaneous EEG. The results are discussed on the basis of a dissociation of sensory and affective components of pain under hypnosis.
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Randomized Controlled Trial Comparative Study Clinical Trial
Comparison of hydromorphone continuous subcutaneous infusion and basal rate subcutaneous infusion plus PCA in cancer pain: a pilot study.
In this pilot randomized, double-blind, cross-over study, the effectiveness and safety of hydromorphone administration by continuous subcutaneous (s.c.) infusion (mode A) and by continuous basal rate s.c. infusion + PCA (mode B) were compared in 8 cancer patients. Patients experimented with each infusion mode during 48 h. Statistical analysis was performed on data collected in 7 patients during 36 h from 22:00 h on day 1 to 10:00 h on day 3 and from 22:00 h on day 3 to 10:00 h on day 5. ⋯ Only 2 patients chose mode B at the end of the study, but it was interesting to note that those 2 patients were the youngest of the group. This study demonstrated the effectiveness and safety of both modes of hydromorphone administration. The data suggest that it may be possible to identify particular cancer patients which can really benefit from an association of a basal rate infusion and PCA for opiate administration.