Transdermal fentanyl compared with parenteral buprenorphine in post-surgical pain in swine: a case study

Abstract

SummaryThe 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 longacting analgesics for treatment of surgical pain of longer duration, and bya 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 pm (n = 2) in the treatment of post-thoracotomy pain was compared with that of a trans dermal therapeutic system (TTSI delivering 25 {tg/h (n = 3) or SOflg/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 124 hI and post-operative days I, 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 SOflg/h and experienced adequate pain control. Pigs treated with 25 flg/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 pharmacokinetic data for fentanyl in pigs, the rate of uptake of TIS 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 postoperative activity level were variable. TTS fentanyl at appropriate doses is a cost effective means of delivering basal analgesia following major surgery in pigs.

Effects of epidural morphine and transdermal fentanyl analgesia on physiology and behaviour after abdominal surgery in pigs

“…Harvey-Clark et al (2000) reported that the pain control produced by transdermal fentanyl patches, with a serum concentration range of 0.3-0.6 ng/mL, is comparable to the analgesia produced by buprenorphine in pigs. During this 48 h period, a lower incidence of active behaviours was noted in Group M and in Group P. This inactivity would be caused by a combination of a postoperative passive state and a depressant effect of opioids, as suggested by Harvey-Clark et al (2000). Fentanyl, a synthetic opioid acting on mu receptors, is responsible for some side effects such as inactivity (Rang et al 1996).…”

“…The main purpose of the present study was to determine whether epidural morphine and fentanyl patch would provide analgesia after abdominal surgery. The means of administration were chosen to avoid Laboratory Animals (2006) 40 frequent animal handling, since repeated administration of drugs is also stressful to pigs (Harvey-Clark et al 2000). Further, non-steroidal anti-inflammatory drugs (NSAIDs) which are frequently used for postoperative analgesia (Nolan 2001) were not used, since these pigs were going to be included in experimental infection studies.…”

A Review of Pain Assessment in Pigs

“…Feed intake was used to assess the benefit of ketoprofen compared with flunixin or untreated grower pigs experimentally infected with Actinobacillus pleuropneumoniae (108), and altered feed intake (using a 4-point scale in which 1 indicated no change and 4 inappetance) was used as part of a clinical index score to assess the efficacy of meloxicam in the treatment of sows with mastitis–metritis–agalactia (MMA) (109). Food consumption decreased after thoracotomy surgery in pigs (110), and time spent feeding has been used to assess the efficacy of pain mitigation strategies in pigs undergoing abdominal surgery (111) and a femoral fracture model (112). In a study using a feed reward collection test to assess sows’ motivation to obtain feed rewards with different levels of lameness, moderately and severely lame sows obtained fewer rewards than mildly and non-lame sows (113).…”

Decubital shoulder ulcers in sows: a review of classification, pain and welfare consequences

“…The existing knowledge is based primarily on studies of post-surgical pain, describing how pigs respond differently to acute and prolonged pain, in which the former typically triggers vocalization and escape responses. In contrast, signs of prolonged pain are described as more discrete, for example, inactivity, abnormal behaviour, postural changes or reluctance to change posture (Harvey-Clark et al, 2000). The Danish Veterinary and Food Administration (Anonymous, 2007) has stated, however without any data, that sows with shoulder ulcers may show difficulties in getting up and that they express pain when touched.…”