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February 1, 2000
Clinical Uses of Alpha-2 Adrenergic Agonists
Kamibayashi T, Maze M.
Anesthesiology 2000;93:1345-1349
Commentary by Katherine
Grichnik, M.D.
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Literature Review Index Page
see abstract below
This is a very useful review article, which serves to remind us of the expanding
uses for alpha-2 adrenergic agents. These agents have long been used to treat
patients for a multitude of problems including hypertension and withdrawal
from alcohol or other substances. Additional known effects also include anxiolysis,
sedation, analgesia, and sympatholysis. New roles are now being found for the alpha-2 adrenergic agents which take
advantage of their beneficial effects. This includes the newer alpha-2
adrenergic agent, dexmedetomidine, which has now been approved for use as a
sedative-analgesic in the ICU setting.
The pharmacology of the alpha-2 adrenergic agents is well reviewed in this
article, including information on the three receptor subtypes and which effects
each subtype mediates. Unfortunately, there are no subtype selective agonists
yet; therefore a discrete agent that produces just one effect (e.g. analgesia)
without the side effect of sedation or hypotension is elusive.
The cardiovascular and central nervous system effects of these drugs are
also reviewed. Of interest, there is now evidence that spatial working memory
may be modulated via an alpha-2A adrenoreceptor subtype, raising the possibility
that these drugs may enhance rather than impede cognitive performance after
use. This, of course, is a tantalizing possibility for use of these drugs
in a setting in which sedation and then rapid return of cognitive function
is desired, such as outpatient surgery. However, to date, the alpha-2 adrenergic
agents are not approved for this use, although it is being studied.
The known clinical indications for the alpha-2 adrenergic agents are then
discussed with intraoperative and postoperative applications outlined. These
include uses for analgesia, sedation, shivering, and perioperative myocardial
ischemia. Briefly, dexmedetomidine and clonidine are also compared.
It seems that there will be an increasing use of alpha-2 adrenergic agents
in our practices as we gain familiarity with these agents. We are reminded
not to use these agents without a thorough review of their mechanisms of action,
their effects and known side effects. However, the benefits of these agents
now seem to outweigh the risks of these agents, which should be minimal when
used properly. I urge you to (re)investigate dexmedetomidine and clonidine
for use in your perioperative practices.
ABSTRACT
Clinical Uses of Alpha-2 Adrenergic Agonists
AUTHORS:
Kamibayashi T, Maze M.
SOURCE:
Anesthesiology 2000;93:1345-1349.
ABSTRACT:
No abstract available.
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