Page 59 - BSAVA Guide to Pain Management in Small Animal Practice

BSAVA Guide to Pain Management in Small Animal Practice

VetBooks.ir Butorphanol: Butorphanol is a KOP agonist and in ammatory and analgesic e ects are
a P antagonist. here is con icting evidence,
unrelated B rkman, 199 ; Cashman, 1996;
Vane and Botting, 1997; Burian and eisslinger,
but most anaesthetists agree that butorphanol
is a good sedative but a poor analgesic. Its . Prostaglandins act peripherally as
usefulness as an analgesic is also limited by its proin ammatory mediators, promoting oedema
short duration of action, which is about formation, sensitization of nociceptors and
minutes in dogs, and probably about 6 hyperalgesia. Proposed central mechanisms of
minutes in cats. Butorphanol is useful for action include interference with the descending
antagoni ing unwanted e ects of P nociceptive control system, either mediated by
analgesics (e.g. dysphoria), while maintaining a direct e ect on prostaglandin production, or
some analgesia, and can be titrated to e ect for by interference with endogenous opioid
this purpose. peptides, the serotoninergic mechanisms or
NMDA receptors and excitatory amino acids
Codeine: Codeine is a full MOP agonist and is (Vanegas et al., 1 . NSAI s also interfere with
licensed in dogs in the UK in combination with the mechanisms of cell adhesion, including
paracetamol (acetaminophen) for oral leukocytes, platelets and tumour cells. Speci c
administration. Codeine has very low oral mechanisms of interference with cell adhesion
bioavailability in dogs, but an active metabolite, and their clinical relevance depend on the class
codeine 6 glucuronide, is formed after oral of NSAIDs considered (Cronstein et al., 1994;
administration, which may provide analgesia. Ulrich et al., 6; Silver and Lillich, 16 .
There is very little research on codeine in cats hile older NSAI s were C 1 selective or
and it cannot be recommended in this species. poorly selective COX inhibitors, modern NSAIDs
have greater selectivity towards C , with
diarylimidazol derivatives (coxibs) currently
drugs having the greatest selectivity.
Non steroidal anti in ammatory drugs NSAI s C 1 and C are membrane
include many drugs used to provide analgesia, associated en ymes, with C 1 traditionally
decrease in ammation and control fever. considered the ‘housekeeping’ isoform
Licensed products for use in dogs and cats responsible for physiological production of P s,
include carprofen, cimicoxib, rocoxib, and C the inductive isoform whose activity
ketoprofen, mavacoxib, meloxicam, is increased in pathological conditions. More
robenacoxib, and tolfenamic acid. Considering recent evidence has demonstrated that this
that acute and chronic and persistent distinction is simplistic, and both C 1 and
nociceptive pain have an in ammatory C have physiological and pathological
component in the vast majority of cases, roles. The quantity and quality of prostanoid
NSAIDs play a vital role in providing produced by COXs depends on the tissue and
perioperative and long-term analgesia. They the triggering stimulus; thus the nature of the
are also e ective in treating certain types of cells present in the in ammatory site a ects the
cancer pain. pro le of P production ay ugford et al.,
; ilson and Chandrasekharan, 4;
Mechanism of action Sessions et al., .
NSAIDs are non-narcotic and their mechanism
of action consists mainly of peripheral inhibition Indications, contraindications and
of the activity of cyclo-oxygenase enzyme clinical use
C 1 and C , and thus of tissue NSAIDs are weakly acidic, highly protein-
prostaglandin P biosynthesis, but there is bound compounds, and generally have good
increasing evidence that NSAIDs may also have oral bioavailability. Timing of administration
a central mechanism of action, mostly with respect to anaesthesia, duration of
supported clinically by the fact that anti- treatment, and contraindications are speci c to

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