The coxib NSAIDs: potential clinical and pharmacologic importance in veterinary medicine

Nonsteroidal anti-inflammatory drugs (NSAIDs) are used to control acute and chronic pain as well as to manage oncologic and neurologic diseases in human and veterinary patients. Despite ongoing research and efforts to improve the safety and efficacy of existing drugs, adverse effects such as gastrointestinal irritation, renal and hepatic toxicity, interference with hemostasis, and reproductive problems persist. The true incidence of NSAID-induced adverse effects in animals is unknown, but is likely underestimated, because cats and dogs may be more sensitive than humans to NSAIDs due to alterations in drug metabolism, absorption, and enterohepatic recirculation. NSAIDs produce both analgesia and toxic adverse effects primarily by inhibiting cyclooxygenase (COX), thereby decreasing the production of prostaglandins that signal inflammation and pain as well as mediate physiologic functions such as platelet aggregation, gastric protection, and electrolyte balance in the kidney. The presence of at least 2 COX isoforms may account for variability in NSAID efficacy and toxicity both within and among species. This paper reviews and evaluates the published literature on the safety, pharmacology, uses, and complications of a subclass of COX-1-sparing drugs, the coxibs, in veterinary medicine. Coxibs and other COX-1-sparing drugs provide a clinically useful improvement over traditional NSAIDs, but data are incomplete and more in vivo species-specific, target-tissue, and clinical studies are needed.