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Differential effects of dipyrone, ibuprofen and paracetamol on experimentally-induced pain in man

Institute of Physiology and Biokybernetics, University of Erlangen, Germany.
Agents and Actions 02/1992; 35(1-2):112-21. DOI: 10.1007/BF01990960
Source: PubMed

ABSTRACT In a double-blind cross-over study on 22 healthy subjects the analgesic efficacies of the antipyretic analgesic drugs ibuprofen, dipyrone and paracetamol were tested against placebo using a model of experimentally induced pain. To this purpose interdigital webs were pinched repeatedly for 2 min periods. The painfulness of these stimuli was assessed by the subjects on an electronically controlled visual analogue scale at 10 sec intervals. In addition to the subjective pain ratings the stimulus induced reflex diminution of the blood flow in the stimulated hand was measured with photoplethysmography and laser Doppler flow analysis. The flare response around the stimulated area was assessed with infrared thermography. In this assay system ibuprofen and dipyrone, but not paracetamol, showed statistically significant analgesic effects by preventing hyperalgesia which is normally induced by the repeated stimulation of a skin site. This hypoalgesic effect was not related to the subjective impression of the subjects of the analgesic potency of the respective drug. Sympathetic reflex vasoconstriction was not quantitatively related to the drug induced hypoalgesia. Ibuprofen and, to a minor extent, the other antipyretic analgesic drugs also diminished the stimulus induced flare reaction around the stimulated skin sites.

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    • "Mean of scores between 30 and 140 min 1.6% Forster et al. 1992 Ibuprofen 800 mg Mean of scores between 30 and 140 min 3.9% Forster et al. 1992 600 mg Mean of scores between 90 and 240 min 12% Petersen et al. 1997 600 mg 100 min (experiment on UVB-irradiated skin). 12% Bickel et al. 1998 Dipyrone 1000 mg Mean of scores between 30 and 140 min 6.7% Forster et al. 1992 Experimental pain was induced by pinching the interdigital webs. Scores approximated from histograms and curves (). Figure 1. "
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    ABSTRACT: The aim of this study was to compare the effects of total sleep deprivation (TSD), rapid eye movement (REM) sleep and slow wave sleep (SWS) interruption and sleep recovery on mechanical and thermal pain sensitivity in healthy adults. Nine healthy male volunteers (age 26–43 years) were randomly assigned in this double blind and crossover study to undergo either REM sleep or SWS interruption. Periods of 6 consecutive laboratory nights separated by at least 2 weeks were designed as follows: N1 Adaptation night; N2 Baseline night; N3 Total sleep deprivation (40 h); N4 and N5 SWS or REM sleep interruption; N6 Recovery. Sleep was recorded and scored using standard methods. Tolerance thresholds to mechanical and thermal pain were assessed using an electronic pressure dolorimeter and a thermode operating on a Peltier principle. Relative to baseline levels, TSD decreased significantly mechanical pain thresholds (−8%). Both REM sleep and SWS interruption tended to decrease mechanical pain thresholds. Recovery sleep, after SWS interruption produced a significant increase in mechanical pain thresholds (+ 15%). Recovery sleep after REM sleep interruption did not significantly increase mechanical pain thresholds. No significant differences in thermal pain thresholds were detected between and within periods. In conclusion this experimental study in healthy adult volunteers has demonstrated an hyperalgesic effect related to 40 h TSD and an analgesic effect related to SWS recovery. The analgesic effect of SWS recovery is apparently greater than the analgesia induced by level I (World Health Organization) analgesic compounds in mechanical pain experiments in healthy volunteers.
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Clemens Forster