FARMACI ANALGESICI ED ANTIINFIAMMATORI PER LA TERAPIA DEL DOLORE IN DIVERSE SPECIE ANIMALI DI INTERESSE VETERINARIO

Nowadays, complex surgery can be carried out on extremely fragile and elderly patients since the anaesthesiologist has taken on a greater role in managing the patient during the peri-operative period (i.e. pre-operative, intra-operative and post-operative periods). As part of this evolution, the postoperative pain control takes on a fundamental role, which goes beyond assuring proper patient analgesia, with the aim to ensure comfort and quality of life. Pre-emptive analgesia seems to constitute one of the most innovative and promising strategies for better pain control throughout the peri- and post-operative period. It is possible to obtain analgesia with pharmacologic treatment operating in different levels of pain nociception, so that it is important to know the different mechanisms and ways through pain is perceived, transmitted and modulated. Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used in veterinary medicine to manage various types of pain. Besides to their peripheral anti-prostaglandin effects, that make them the first choice for minimizing development of peripheral sensitization of nociceptors, NSAIDs are considered to have central-acting analgesic effects, thanks to the inhibition of cyclooxygenase (COX) also within the dorsal horn of spinal cord . Opioids are the class of drugs that play the most significant role in descending nociceptive modulatory pathways through their actions at multiple levels. Despite their administration is associated to the potentially serious adverse effects, opioids remain among the most powerful and efficacious analgesics available. In this thesis the pharmacokinetic profile and the peri-operative analgesic efficacy of Tramadol (synthetic opioid, μ-receptors agonist) and Ketorolac (NSAID) were evaluated after administration in dogs, cats and horses. The two drugs were administered in animals undergoing moderately painful surgery (gonadectomy) and the pain degree was assessed by using numerical scales by a trainee observer. Blood samples for drugs quantification were collected at pre-established times and the pharmacokinetic analysis was carried out on results. Both drugs demonstrated to have good analgesic activity in the post- operative period without manifesting adverse effects in all species. The extradural administration of tramadol in dog showed an analgesic and kinetic profile similar to the intravenous route. Ketorolac is not currently approved for use in veterinary medicine. However, thanks to its characteristics it could be safety used as analgesic in these species. It will be of interest to investigate the association of the two molecules in a multimodal protocol, in which tramadol should promote the analgesic effect during the intra-operative period and the initial period after surgery, whereas ketorolac, thanks to its longer duration of activity, should be administered later to prolong the analgesia during the post-operative period.