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Transdermal fentanyl compared
with parenteral buprenorphine in post-surgical
pain in swine: a case study
C. J. Harvey-Clark1,
K. Gilespie2
& K. W. Riggs3
1University Director
of Animal Care, Honorary Adjunct Professor, Department
of Psychology, Dalhousie University, Halifax,
Nova Scotia, Canada, 2Chief
Technician, Animal Research Laboratories, Jack
Bell Research Center, Vancouver General Hospital,
Vancouver, British Columbia, Canada and 3Associate
Professor, Department of Pharmacology, University
of British Columbia, Vancouver, British Columbia,
Canada
Summary
The use of pigs as research animals in survival
surgery has increased greatly in the last 15 years.
Personnel conducting pig research have been hampered
by a lack of proven long-acting analgesics for
treatment of surgical pain of longer duration,
and by a lack of reliable non-subjective parameters
for the assessment of pain relief. The efficacy
of the mixed opioid agonist-antagonist buprenorphine
hydrochloride 0.10 mg/kg prn (n = 2) in the treatment
of post-thoracotomy pain was compared with that
of a transdermal therapeutic system (TTS) delivering
25 ug/h (n = 3) or 50 ug/h (n = 2) of the mu opioid
agonist fentanyl hydrochloride. Food consumption,
pain score, activity level and rate of movement
were assessed under four conditions: normal pre-operative
control (24 h), pre-operative with analgesic alone
(24 h) and post-operative days 1, 2, 3 (72 h).
Serum concentration-time curves for fentanyl in
clinical cases revealed that female Yorkshire
cross pigs weighing 26.2 ± 2.1 kg achieved
serum values in the recognized human therapeutic
range when treated with TTS fentanyl at 50 ug/h
and experienced adequate pain control. Pigs treated
with 25 ug/h TTS fentanyl had serum levels below
the human analgesic range, experienced less adequate
analgesia, and required supplemental analgesia
in some cases. Based on existing pharmaco kinetic
data for fentanyl in pigs, the rate of uptake
of TTS fentanyl when attached on inter-scapular
skin was lower than predicted. Clinical pain scores
and time intervals between each major postural
change were not affected by analgesics in the
absence of pain, but increased in all groups after
surgery regardless of treatment. Food consumption
was unaffected by analgesic treatment alone but
decreased in all groups after surgery regardless
of treatment. Analgesic effects on post- operative
activity level were variable. TTS fentanyl at
appropriate doses is a cost effective means of
delivering basal analgesia following major surgery
in pigs.
Keywords Pain; surgery; thoracotomy;
analgesia; pig; swine; laboratory animal; fentanyl;
buprenorphine; transdermal; pharmacokinetics;
analgesiometry; welfare; fentanyl patch
© 2000, Laboratory Animals Ltd.
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