Pain
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Comparative Study Clinical Trial Controlled Clinical Trial
A modified cold stimulation technique for the evaluation of analgesic activity in human volunteers.
This report describes the effects of a modified cold pressure technique (MCP) on the dominant hand of 6 healthy right-handed volunteers, after single p.o. doses of codeine (60 mg), aspirin (1 g) and placebo in a cross-over, double-blind design. The method employed 9 serial tests on each study day, involving 5 consecutive 2 min periods of hand immersion in an equilibrating bath at constant temperature (37 degrees C), followed by a stimulating bath (0 degree C +/- 0.5) containing 15% ethylene glycol. ⋯ Codeine was statistically different from placebo (P less than 0.05). It is concluded that this modified technique offers a stable and sensitive method for the early assessment of analgesic activity.
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Comparative Study
Corticosteroids suppress ectopic neural discharge originating in experimental neuromas.
Some injured sensory fibers ending in an experimental neuroma in the rat sciatic nerve discharge spontaneously. Furthermore, many become sensitive to a range of physical and chemical stimuli. ⋯ These corticosteroids also produce a rapid and prolonged suppression of ongoing discharge in chronic neuromas that have already become active. The kinetics of corticosteroid suppression of neuroma discharge suggest a direct membrane action rather than an anti-inflammatory action.
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The objectives of this study were to investigate the duration of analgesia and the development of tolerance following continuous intrathecal administration of morphine and norepinephrine alone, and morphine followed by norepinephrine via mini-osmotic pumps in the rat. Analgesia was assessed by the tail-flick test. In single pump experiments morphine 1 microliter (10 micrograms)/h (7 days) and 0.5 microliter (10 micrograms)/h (14 days) produced analgesia with tolerance by days 5-7. ⋯ Following continuous intrathecal morphine 1 microliter (10 micrograms)/h for 5 days, norepinephrine 1 microliter (15 micrograms)/h for 7 days failed to produce a significant increase in analgesia. This was in contrast to the increase in analgesia seen when the norepinephrine infusion followed a saline infusion. Determination of the norepinephrine concentration in the solution from the osmotic pumps verified that the norepinephrine is stable for the treatment period.