Antinociceptive effects of combining low doses of neuroleptic drugs and fentanyl in sheep

Andrew Edward Kyles From the Departments of Veterinary Surgery (Kyles, Waterman) and Pharmacology (Livingston), University of Bristol, Bristol, BS18 7DU, England

Search for other papers by Andrew Edward Kyles in
Current site
Google Scholar
PubMed
Close
 BVMS, PhD
,
Avril Eira Waterman From the Departments of Veterinary Surgery (Kyles, Waterman) and Pharmacology (Livingston), University of Bristol, Bristol, BS18 7DU, England

Search for other papers by Avril Eira Waterman in
Current site
Google Scholar
PubMed
Close
 BVSc, PhD
, and
Alex Livingston From the Departments of Veterinary Surgery (Kyles, Waterman) and Pharmacology (Livingston), University of Bristol, Bristol, BS18 7DU, England

Search for other papers by Alex Livingston in
Current site
Google Scholar
PubMed
Close
 B Vetmed, PhD

Click on author name to view affiliation information

Summary

Effects of low doses of the neuroleptic drugs droperidol and zuclopenthixol, combined with a sub-analgesic dose of the opioid µ-agonist, fentanyl, on mechanical nociceptive thresholds were evaluated in sheep. Intravenously administered droperidol (5 µg/kg of body weight) did not induce any change in the nociceptive thresholds when administered alone, but caused marked increase in threshold responses when combined with a subanalgesic dose of fentanyl (5 µg/kg). Similarly, a combination of IV administered zuclopenthixol (100 µg/kg) and fentanyl induced significant (P< 0.05) antinociceptive effects, whereas zuclopenthixol administered IV alone had no effect on the threshold responses. Intrathecal administration of a low dose of droperidol (5-µg total dose) combined with IV administered fentanyl also increased mechanical thresholds significantly (P< 0.05). These results indicate that interactions exist between dopaminergic and opioid systems in the processing of nociceptive information and that these effects may, at least partially, be mediated spinally.

Summary

Effects of low doses of the neuroleptic drugs droperidol and zuclopenthixol, combined with a sub-analgesic dose of the opioid µ-agonist, fentanyl, on mechanical nociceptive thresholds were evaluated in sheep. Intravenously administered droperidol (5 µg/kg of body weight) did not induce any change in the nociceptive thresholds when administered alone, but caused marked increase in threshold responses when combined with a subanalgesic dose of fentanyl (5 µg/kg). Similarly, a combination of IV administered zuclopenthixol (100 µg/kg) and fentanyl induced significant (P< 0.05) antinociceptive effects, whereas zuclopenthixol administered IV alone had no effect on the threshold responses. Intrathecal administration of a low dose of droperidol (5-µg total dose) combined with IV administered fentanyl also increased mechanical thresholds significantly (P< 0.05). These results indicate that interactions exist between dopaminergic and opioid systems in the processing of nociceptive information and that these effects may, at least partially, be mediated spinally.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 95 95 20
PDF Downloads 24 25 3
Advertisement