ALPHA(2) ADRENOCEPTOR AGONISTS IN THE HORSE - A REVIEW

In recent years the usefulness of the alpha(2) adrenoceptor agonist dr ugs has been recognized in equine practice. Several agents have become available and are now licensed for use in a number of countries. The principle actions of all alpha(2) adrenoceptor agonists are similar, i n that they produce a reduction in heart rate and alteration of heart rhythm, an initial hypertension followed by a prolonged hypotension, a decrease in the cardiac output and respiratory depression. For clinic al purposes, these agents produce sedation and analgesia, they are use ful for premedication and markedly potentiate the effects of other sed ative/analgesic agents. Differences in receptor specificity between th e alpha(2) adrenoceptor agonists results in the distinguishing charact eristics of the individual agents, particularly with respect to their duration of action, sedative effect and analgesic properties; their ca rdiopulmonary effects are however similar, when equipotent sedative do ses are administered. When used in combination with other agents, the alpha(2) adrenoceptor agonists all appear to act in a similar manner, with the greatest difference being related to their duration of action .