Pathophysiology of cyclooxygenase inhibition in animal models.
Cyclooxygenase (COX) catalyzes the conversion of arachidonic acid into prostaglandins (PGs), which play a significant role in health and disease in the gastrointestinal tract (GI) and in the renal, skeletal, and ocular systems. COX-1 is constitutively expressed and found in most normal tissues, whereas COX-2 can be expressed at low levels in normal tissues and is highly induced by pro-inflammatory mediators. Inhibitors of COX activity include: (1) conventional nonselective, nonsteroidal anti-inflammatory drugs (ns-NSAIDs) and (2) COX-2 selective nonsteroidal anti-inflammatory drugs (COX-2 s-NSAIDs). Inhibition of COX-1 often elicits GI toxicity in animals and humans. Therefore, COX-2 s-NSAIDs were developed to provide a selective COX-2 agent, while minimizing the attendant COX-1-mediated GI toxicities. Rats and dogs overpredict COX inhibition for renal effects such as renal handling of electrolytes in humans. COX inhibitors are shown to have both beneficial and detrimental effects, such as on healing of ligament or tendon tears, on the skeletal system in animal models. Certain ophthalmic conditions such as glaucoma and keratitis are associated with increased COX-2 expression, suggesting a potential role in their pathophysiology.
Radi
Zaher A
ZA
Pfizer Global R&D, Drug Safety R&D, St. Louis, Missouri 63017, USA. zaher.radi@pfizer.com
D000818:Animals; D016861:Cyclooxygenase Inhibitors / Q000378:metabolism / Q000494:pharmacology*; D004195:Disease Models, Animal; D004285:Dogs; D005123:Eye / Q000187:drug effects / Q000201:enzymology / Q000503:physiopathology; D017102:Fracture Healing / Q000187:drug effects / Q000502:physiology; D005767:Gastrointestinal Diseases / Q000139:chemically induced* / Q000201:enzymology / Q000503:physiopathology*; D041981:Gastrointestinal Tract / Q000187:drug effects* / Q000201:enzymology / Q000503:physiopathology*; D007413:Intestinal Mucosa / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D007668:Kidney / Q000187:drug effects / Q000201:enzymology / Q000503:physiopathology; D008022:Ligaments / Q000187:drug effects / Q000293:injuries / Q000503:physiopathology; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D051381:Rats; D013708:Tendon Injuries / Q000188:drug therapy / Q000201:enzymology / Q000503:physiopathology
D016861:Cyclooxygenase Inhibitors; D011451:Prostaglandin-Endoperoxide Synthases