Journal Article10.1124/PR.111.005447
Human Experimental Pain Models for Assessing the Therapeutic Efficacy of Analgesic Drugs
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TL;DR: In general, the sensitivity to analgesics is better in patients than in healthy volunteers, but the lower number of studies may bias the results, so knowledge obtained can help design experimental pain studies for new compounds entering phase I and II clinical trials.
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Abstract: Pain models in animals have shown low predictivity for analgesic efficacy in humans, and clinical studies are often very confounded, blurring the evaluation. Human experimental pain models may therefore help to evaluate mechanisms and effect of analgesics and bridge findings from basic studies to the clinic. The present review outlines the concept and limitations of human experimental pain models and addresses analgesic efficacy in healthy volunteers and patients. Experimental models to evoke pain and hyperalgesia are available for most tissues. In healthy volunteers, the effect of acetaminophen is difficult to detect unless neurophysiological methods are used, whereas the effect of nonsteroidal anti-inflammatory drugs could be detected in most models. Anticonvulsants and antidepressants are sensitive in several models, particularly in models inducing hyperalgesia. For opioids, tonic pain with high intensity is attenuated more than short-lasting pain and nonpainful sensations. Fewer studies were performed in patients. In general, the sensitivity to analgesics is better in patients than in healthy volunteers, but the lower number of studies may bias the results. Experimental models have variable reliability, and validity shall be interpreted with caution. Models including deep, tonic pain and hyperalgesia are better to predict the effects of analgesics. Assessment with neurophysiologic methods and imaging is valuable as a supplement to psychophysical methods and can increase sensitivity. The models need to be designed with careful consideration of pharmacological mechanisms and pharmacokinetics of analgesics. Knowledge obtained from this review can help design experimental pain studies for new compounds entering phase I and II clinical trials.
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Citations
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Cannabinoids and Pain: New Insights From Old Molecules
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Tine van de Donk,Marieke Niesters,Mikael A. Kowal,Erik Olofsen,Albert Dahan,Monique van Velzen +5 more
TL;DR: This experimental trial shows the complex behavior of inhaled cannabinoids in chronic pain patients with just small analgesic responses after a single inhalation, indicative of synergistic pharmacokinetic but antagonistic pharmacodynamic interactions of THC and CBD.
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Automatic Recognition Methods Supporting Pain Assessment: A Survey
Philipp Werner,Daniel Lopez-Martinez,Steffen Walter,Ayoub Al-Hamadi,Sascha Gruss,Rosalind W. Picard +5 more
TL;DR: The state of the art of pain recognition technology is assessed and guidance is provided for researchers to help make such advances to identify underexplored areas such as chronic pain and connections to treatments, and promising opportunities for continued advances.
199
Age-related changes in pain sensitivity in healthy humans: A systematic review with meta-analysis.
H. El Tumi,H. El Tumi,Mark I. Johnson,P.B.F. Dantas,P.B.F. Dantas,Maria J Maynard,Osama A. Tashani,Osama A. Tashani +7 more
TL;DR: There is tentative evidence that pressure pain threshold was lower in old adults compared with younger adults, with no differences in heat pain thresholds, and younger children were more sensitive to noxious stimuli than older children.
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