European journal of pain : EJP
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The present study has assessed the relationship between formalin-induced nociception and formalin-induced inflammation by comparing the dose-related effects of anti-inflammatory treatments on both nociceptive scores and plasma extravasation in the rat hind paw in response to high and low concentrations of formalin. The degree of plasma extravasation produced by 1% formalin did not differ significantly from that produced by the same volume of saline, and was not significantly affected by either of the anti-inflammatory agents. The 5% formalin injection produced significant plasma extravasation that was dose-dependently reduced by both dexamethasone and ibuprofen. ⋯ The present study suggests that there is a positive correlation between the nociceptive and inflammatory effects of formalin in the rat hind paw. However, only a high concentration of formalin, which produces significant plasma extravasation, is capable of demonstrating the antinociceptive effects of anti-inflammatory agents, and the effects are restricted to the late phase of the formalin test. Copyright 1998 European Federation of Chapters of the International Association for the Study of Pain.
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A double-blind, randomized, placebo-controlled trial was conducted to study the analgesic efficacy of the NMDA (N-methyl-D-aspartate) receptor antagonist memantine (1-amino-3,5-dimethyladamantane hydrochloride) in relieving postherpetic neuralgia (PHN). Memantine (or an identical-looking placebon=12/group) was administered at a dose of 10 mg/day for one week, and 20 mg/day for an additional 4 weeks. All patients were required to record their pain level twice daily during the entire study period, with the use of a 0-10 numerical pain scale (NPS). ⋯ Although three patients were withdrawn from the memantine group and only one from the control group, no differences in incidence of adverse effects between the two groups were found. Study results show that memantine is ineffective in reducing spontaneous and evoked pain in patients with PHN. Copyright 1998 European Federation of Chapters of the International Association for the Study of Pain.
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The extent of surgical trauma was related to postoperative pain intensity in a previous study. However, more extensive surgical procedures with higher baseline pain intensity did not appear to influence the ability to document the additive analgesic effect of codeine when given with paracetamol, partly due to large interindividual variation in baseline pain intensity. The aim of the present study was to attempt to improve upside assay sensitivity in this dental pain model by: (1) selecting patients with high baseline pain intensity; and (2) closer supervision of outpatients>> drug intake and compliance with protocol. ⋯ More pain relief was revealed when codeine 60 mg was added to paracetamol 1000 mg on the following measures of effect: change of pain intensity with time (p<0.05, Mann-Whitney), sum of pain intensities (p=0.019), pain intensity difference (p=0.05), sum of pain intensity differences (p<0.05), pain reduction index (p<0.05) and global-evaluation score (p=0.006). The study confirms that this dental pain model, when controlled for sufficient and homogeneous baseline pain and patient compliance, does have sufficient upside assay sensitivity to discriminate between paracetamol with and without codeine. Copyright 1998 European Federation of Chapters of the International Association for the Study of Pain.
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We have previously reported that intrathecal (i.t.) implantation of bovine chromaffin cells has an anti-allodynic effect in a rat model of mechanical and cold allodynia-like neuropathic pain after spinal cord injury. The technique of encapsulation of the cells by a semipermeable membrane has been developed recently. The present study was undertaken to investigate the effects of encapsulated bovine chromaffin cells on the allodynia-like pain in the same model. ⋯ The results indicate that spinal implantation of encapsulated xenogeneic chromaffin cells may be useful in treating some refractory painful states associated with spinal cord injury. Immunoisolation of chromaffin cells by a semipermeable membrane may inhibit immunorejection, prolong the survival of the cells and enhance their anti-allodynic effect. Copyright 1998 European Federation of Chapters of the International Association for the Study of Pain.