The [alpha]-2 adrenergic agonists
are the most commonly used in the equine practice, having important dose-dependent effect when higher doses or longer therapeutic times are applied, generating an important hypotensor effect (Muir WW et al., 2009), which is compensated with peripheral vaso-constriction, that, in the case of being prolonged, can affect retinal vessels, causing a pressure increasing and a tissue oxygen input reduction leading to a corioretinopathy and/or optic neuritis.
"Given the risk of long-term neurophysiologic and behavioural impairment, the use of beta 2 adrenergic agonists
should be limited to proven indications when alternate drugs are ineffective or unavailable and the risks of the untreated disease to the mother and fetus are greater than the risk of the beta 2 adrenergic agonist
," said Dr Frank R.
The mechanism of action for salmeterol is a (LABA) long-acting beta 2 adrenergic agonist
. Studies (2007) have shown, "salmeterol is at least 50 times more selective for beta 2 adrenoceptors than albuterol" (p.
A prototypical, short-acting bronchodilator is albuterol (also called salbutamol), a selective beta-2 adrenergic agonist
which relaxes bronchiole smooth muscle.
The nearly immediate analgesic effect observed after intrathecal injection of 300 and 450 micrograms clonidine strongly argues for a spinal rather than a systemic site of action of this alpha-2 adrenergic agonist
, which renders the support to our result in the effect of clonidine on spinal action even in higher doses without significant effect on systemic action.
Originally marketed as an antihypertensive in the early 1970s, the central alpha-2 adrenergic agonist
is now used for a variety of conditions, including menopause symptoms, attention-deficit/hyperactivity disorder, Tourette syndrome, smoking cessation, neuropathic pain, and LSD flashbacks, Dr.
The anaesthetic and analgesic requirement get reduced to much extent by the use of alpha-2 adrenergic agonist
dexmedetomidine as an adjuvant, because of its analgesic properties and augmentation of local anaesthetic effects as they cause hyperpolarisation of nerve tissues by alteration of transmembrane potential and ion conductance at locus coeruleus in the brain stem.
Lofexidine is an investigational non-opioid [[alpha].sub.2] adrenergic agonist
that's been used for more than a decade in the United Kingdom.
Most of the clinical studies about the intrathecal [[alpha].sub.2] adrenergic agonist
are related to clonidine, acts as an analgesic, a sedative and as a sympatholytic with potent antinociceptive properties.
Dexmedetomidine is a highly selective [alpha]-2 adrenergic agonist
with an affinity of eight times greater than that of clonidine.