Tramadol-induced hyperalgesia and its prevention by ketamine in rats. Issue 10 (October 2015)

• Record Type: Journal Article
• Authors: Abreu, Mariana; Aguado, Delia; Benito, Javier; García-Fernández, Javier; Gómez de Segura, Ignacio A.
• Is Part Of: European journal of anaesthesiology. Volume 32:Issue 10(2015:Oct.)
• Publication Date: 2015-10
• Subjects: Anesthesiology -- Periodicals; Anesthesiology -- Periodicals; Anesthésiologie -- Périodiques; Anesthesiology; Periodicals; Electronic journals; 617.96
• DOI: 10.1097/EJA.0000000000000296
• Languages: English
• ISSNs: 0265-0215

Abstract

<abstract> <title> <x xml:space="preserve">Abstract</x> </title> <sec> <title>BACKGROUND</title> <p>Opioid analgesia not only reduces inhalational anaesthetic requirements but may also induce delayed hyperalgesia, with potential effects on the minimum alveolar concentration (MAC) of inhalational anaesthetics.</p> </sec> <sec> <title>OBJECTIVES</title> <p>The objective of this study was to evaluate the development of tramadol-induced hyperalgesia and the associated changes in MAC, and whether ketamine prevents both processes.</p> </sec> <sec> <title>DESIGN</title> <p>A randomised, experimental study.</p> </sec> <sec> <title>SETTING</title> <p>Experimental Surgery Unit, La Paz University Hospital, Madrid, Spain.</p> </sec> <sec> <title>ANIMALS</title> <p>Thirty-nine adult male Wistar rats.</p> </sec> <sec> <title>INTERVENTIONS</title> <p>Mechanical nociceptive thresholds (MNT) were determined up to 21 days after the intraperitoneal administration of a single dose of tramadol (50 mg kg<sup>−1</sup>) with or without ketamine (10 mg kg<sup>−1</sup>), or 0.9% saline. The MNT and the MAC of sevoflurane were also assessed in a second experiment before, early (30 min) and 7 days after drug administration with the same treatments.</p> </sec> <sec> <title>MAIN OUTCOME MEASURES</title> <p>The MAC and MNT were evaluated. The analysis of variance (ANOVA) test was employed to determine differences between treatments and times on MAC and MNT.</p> </sec> <sec> <title>RESULTS</title> <p>Tramadol, alone or combined with ketamine, produced an early increase in MNT. However, tramadol given alone decreased MNT from day 1 up to 3 weeks, which was associated with an increase in the MAC of sevoflurane (<italic>P</italic> < 0.05; day 7). Ketamine administration prevented both the reduction in MNT and the increase in MAC (<italic>P</italic> > 0.05).</p> </sec> <sec> <title>CONCLUSION</title> <p>Tramadol-induced hyperalgesia in the rat lasted for several weeks and was associated with an increase in the MAC of sevoflurane. Prior administration of ketamine blocked both phenomena.</p> </sec> </abstract>