• Metabolism: Hepatic. Celecoxib metabolism is primarily mediated via cytochrome P450 2C9. Three metabolites, a primary alcohol, the corresponding carboxylic acid and its glucuronide conjugate, have been identified in human plasma. CYP3A4 is also involved in the hydroxylation of celecoxib but to a lesser extent. These metabolites are inactive as COX-1 or COX-2 inhibitors. Route of Elimination: Celecoxib is eliminated predominantly by hepatic metabolism with little (<3%) unchanged drug recovered in the urine and feces. 57% of the oral dose is excreted in the feces and 27% is excreted into the urine. The primary metabolite in urine and feces was the carboxylic acid metabolite (73%). The amount of glucuronide in the urine is low. Half Life: The effective half-life is approximately 11 hours when a single 200 mg dose is given to healthy subjects. Terminal half-life is generally variable because of the low solubility of the drug thus prolonging absorption.
• Uses/Sources: For relief and management of osteoarthritis (OA), rheumatoid arthritis (RA), juvenile rheumatoid arthritis (JRA), ankylosing spondylitis, acute pain, primary dysmenorrhea and oral adjunct to usual care for patients with familial adenomatous polyposis
• Symptoms: Symptoms of overdose include breathing difficulties, coma, drowsiness, gastrointestinal bleeding, high blood pressure, kidney failure, nausea, sluggishness, stomach pain, and vomiting.
• Route of Exposure: Well absorbed in the gastrointestinal tract. When a single dose of 200 mg is given to healthy subjects, peak plasma levels occur 3 hours after an oral dose. The peak plasma level is 705 ng/mL. Absolute bioavailability studies have not been conducted. When multiple doses are given, steady-state is reached on or before Day 5. When taken with a high fat meal, peak plasma levels are delayed for about 1 to 2 hours with an increase in total absorption (AUC) of 10% to 20%.

The mechanism of action of celecoxib is believed to be due to inhibition of prostaglandin synthesis. Unlike most NSAIDs, which inhibit both types of cyclooxygenases (COX-1 and COX-2), celecoxib is a selective noncompetitive inhibitor of cyclooxygenase-2 (COX-2) enzyme. It binds with its polar sulfonamide side chain to a hydrophilic side pocket region close to the active COX-2 binding site. Both COX-1 and COX-2 catalyze the conversion of arachidonic acid to prostaglandin (PG) H2, the precursor of PGs and thromboxane.