Pharmacological therapeutics and implications of opioid administration in veterinary practices: A current perspective

Abstract

Through the years, many synthetic or partially synthetic opioid agonists have also been developed that are being employed in medicinal therapeutics. Mu, kappa and delta which have been named after Greek alphabets are some of the most prolific opioid receptors targeted for their analgesic and sedative effect. However, serious cardiovascular implications and extremely addictive nature of these drugs have limited their widespread application. Patients who have been prescribed opioids, need to be systematically weaned-off, as abrupt cessation of use may lead to debilitating withdrawal effects. Cognizance regarding the physiology of pain stimulus and neural pathways associated with sensation of pain would be essential to develop anti-nociceptive therapeutic regimens. Both ascending and descending nociceptive pathways which include Primary Afferent fibers, Dorsal Horn Neurons, Ascending Spinal Tracts, Thalamocortical structures, Periaqueductal gray matter (PAG) and Rostroventral medulla (RVM), all have receptors for opioids and alpha 2agonists. It has already been established that the anesthetic efficacy and pain management could be significantly improved by engaging both of these receptor agonists in multimodal pain management protocols. Yet, the fear of misuse has often limited implementation of opioid therapy in veterinary settings. In this review, authors have intended to summarize the pharmacological action of opioids and their possible application for therapeutic purposes. Scientists would find this review quite insightful for devising innovative multimodal approaches and stipulating future research endeavors for development of opioids derivative devoid of their pernicious addictive tendencies.