Small Animal Clinical Pharmacology - CYF MEDICAL DISTRIBUTION

CHAPTER 13 NONSTEROIDAL ANTI-INFLAMMATORY DRUGS AND CHONDROPROTECTIVE AGENTS
Relevant pharmacokinetic data
Firocoxib has a half-life in dogs of approximately 7.8 h.
In horses, it averages 30–40 h. Steady-state concentrations
are achieved in horses beyond 6–8 daily oral doses.
In cats, the half-life is reported to range from approximately
9 to 12 h.
Adverse effects
Adverse events reported are those typical for the NSAID
class.
Flunixin meglumine
(Banamine ® and generic)
Clinical applications
Flunixin is one of the most potent inhibitors of COX.
It is registered for use in dogs in some countries but not
in the United States, where it is only approved for use
in horses and cattle. It has been shown to provide good
analgesia for acute and surgical pain (better, for example,
than butorphanol) but the potential for side effects is of
major concern. It has been used as a postoperative analgesic
(single dose only) in cats, although it is not
approved for use in this species.
Flunixin has been shown to have similar efficacy to
phenylbutazone in the management of acute flare-ups
of musculoskeletal disorders in dogs. This is in contrast
to horses, where flunixin is a better anti-inflammatory
and analgesic than phenylbutazone. The development
of equally or more efficacious and safer NSAIDs that
can be given by parenteral as well as oral routes means
that there are now few indications for the use of flunixin
in the safe management of acute or chronic pain in dogs
or cats.
Flunixin is effective in the management of a variety
of inflammatory ocular conditions, particularly if given
prophylactically. It is also used as an adjunct in the
treatment of endotoxic shock and has been demonstrated
to increase survival in dogs with experimental
septic peritonitis and after injection with Escherichia
coli endotoxin. In dogs with experimental gastric dilation
and torsion, flunixin did not alter cardiac indices
or blood flows significantly but did reduce prostacyclin
levels, suggesting that it may attenuate or inhibit the
continued effects of endotoxic damage. Other NSAIDs
may have similar beneficial effects in endotoxemia.
Formulations and dose rates
Flunixin is available in oral and injectable formulations.
DOGS
Surgical pain
• 1.1 mg/kg IV, SC or IM q.24 h, maximum of 3 doses (1 dose
preferred)
Pyrexia
• 0.25 mg/kg IV, SC or IM q.24 h or q.12 h PRN for 1–2
treatments
Ophthalmological procedures
• 0.25–1.0 mg/kg q.24 h or q.12 h PRN for 1–2 treatments
CATS
Surgical pain
• 0.25–1.0 mg/kg IV, SC or IM q.24 h, maximum of 3 doses
(1 dose preferred)
Pyrexia
• 0.25 mg/kg IV, SC or IM q.24 h or q.12 h PRN for 1–2
treatments
Mechanism of action – additional information
Flunixin is an aminonicotinic acid NSAID.
Relevant pharmacokinetic data
Flunixin has a short half-life in dogs of 2.4–3.7 h but
sequesters in inflamed tissues, resulting in a duration of
action of approximately 24 h. Mean elimination halflife
in cats has been reported to be 0.7–1.5 h.
Adverse effects
Significant gastrointestinal toxicity occurs in dogs with
chronic use; therefore, acute and preferably single dose
use only is advisable.
Additional known or suspected drug interactions
Significant renal dysfunction has been documented in
dogs anesthetized with methoxyflurane and given a
single dose of flunixin (1.0 mg/kg).
Indometacin and copper indometacin
(Cu-Algesic ® )
Indometacin is commonly used in humans. It is an
acetic acid derivative and a member of the indoline
class. Despite its short half-life in dogs (0.3 h), indometacin
is highly ulcerogenic at doses of 1 mg/kg, 5%
of the toxic dose in humans.
Indometacin is marketed in Australia in combination
with copper for use in dogs and horses. Copper is
reported to have anti-inflammatory and antioxidant
effects. Copper-complexed NSAIDs are reported to be
more potent anti-inflammatory agents than NSAIDs
alone in laboratory animals. The copper–NSAID formulation
is said to alter the pharmacokinetics of the compound
sufficiently (reduced enterohepatic recycling) to
result in reduced potential for gastrointestinal toxicity.
To date, controlled clinical trials have not been conducted
to prove or disprove the compound’s efficacy in
the management of inflammatory disorders in dogs and
horses. However, uncontrolled clinical trials support the
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