UWMadison School of Veterinary Medicine © Copyright 2009
by
UW-Madison School of Veterinary Medicine
Research beagles helped test initial
dosages of the new
liposome-encapsulated
opioids, or extended release
pain medication, developed
by Dr. Lesley Smith,
anesthesiologist at the
UW-Madison School of
Veterinary Medicine. The
goal is to prevent pain
without over-sedating the
patient.
November 2008
A new, injectable pain-relieving drug formulation for animals might eliminate
more than pain.
If clinical
trials go as well as initial
studies have indicated, it’s
possible that animals recovering
from major surgery could avoid a
lengthy hospital stay. Instead,
after their veterinarian gives
them a shot, they could head
home free of pain for either
five days (if their pain is
acute) or 21 days (if they have
chronic pain), depending on
which formulation of this
medication is given.
“We’re hoping
our new pain relief injections
will perform as well as or
better than the current standard
of care, which is usually a
continuous drip of fentanyl
analgesic via an intravenous
catheter,” says Dr. Lesley
Smith, a veterinary
anesthesiologist at the
UW-Madison School of Veterinary
Medicine.
So far, the
liposome-encapsulated opioids,
developed by Timothy D. Heath at
the UW School of Pharmacy and
Lisa Krugner-Higby of the
Research Animal Resources
Center, have provided steady,
long-acting pain relief, coupled
with ease of use.
This is the
first extended-release product
that delivers opioids
continuously and effectively to
the patient. Opioids are one of
the best pain relief options
available, but because they are
a controlled substance, they
must be administered in a
hospital setting. In dogs and
other veterinary species, oral
extended-release opioids do not
work because they are
metabolized quickly in the liver
after ingestion and never reach
effective blood levels.
New
pain medication developed by
Dr. Lesley Smith at the
University of Wisconsin
School of Veterinary
Medicine consists of a
long-lasting injectable
(5-day and 21-day pain
relief), eliminating the
need for intravenous
catheters and constant
monitoring. After helping
Dr. Smith determine the
correct dosages of the drug,
beagles in the study were
adopted into private homes.
Dr. Smith
carried out the initial studies
to determine the appropriate
dosages in beagles, with
excellent results. The dogs
were rated for level of
sedation, ranging from
completely asleep, to awake but
groggy (lifts head when petted),
to awake and normal.
“We don’t
want to over sedate the
patients,” Dr. Smith notes.
“Owners would not perceive that
as a good quality of life for
their pet.”
She is now
eager to begin clinical trials
(that is, in actual client
animals) of the new pain relief
medication. In fact, the
long-term hope is that this
formulation might have human
applications as well.
The
shorter-acting version of the
injectable drug is best for
acute post-operative pain, such
as occurs after limb amputation
due to cancer. The
longer-acting version is best
for chronic pain.
“Because this
is injectable, and intravenous
catheters and constant
observation are not necessary,
the patient will not have to
stay in a critical care unit,”
says Dr. Smith. “Another
advantage is that the pain
relief is more steady, without
the bolus effect of the catheter
method.”
Initial
funding for the study was
provided by the school’s
Companion Animal Fund. Based on
early results, the Morris Animal
Foundation and National
Institutes of Health became
interested and provided
additional funding. All of the
beagles involved in the initial
trials have been adopted into
loving homes.
Editor’s
note: Clinical trials are never
done without the client’s
approval. In some cases,
partial costs may be covered by
a study to entice animal owners
to participate.
see original article here
