The antinociceptive activity and respiratory effects of fentanyl in sheep |
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| Authors: | A E Waterman A Livingston A Amin |
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| Institution: | Department of Veterinary Surgery, University of Bristol, Langford House, Langford, Bristol, Avon. BS18 7DU.;*Department of Pharmacology, University of Bristol, Langford House, Langford, Bristol, Avon. BS18 7DU. |
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| Abstract: | The analgesic activity of fentanyl was measured in sheep using both thermal and mechanical test systems. Fentanyl at a dose rate of 5 μg/kg given intravenously (iv) produced significant analgesia to thermal pain for some 30 mins but no detectable mechanical antinociceptive activity. However, at a dose rate of 10 μg/kg the drug produced both thermal (for 60 mins) and mechanical (40 mins) antinociceptive effects. In one sheep a dose of 20 μg/kg produced thermal analgesia for 110 mins and mechanical antinociception for 60 mins. Following iv injection at 10 μg/kg in five of the sheep, there was a brief period of respiratory depression evidenced by a significant fall in PaCO2 of the order of 25 per cent and an increase in PCO2 levels, but these changes were short lived and levels were back to normal at 15 mins after injection. |
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