Celecoxib was the first specific inhibitor of COX-2 approved to treat patients with rheumatism and osteoarthritis. A study showed that the absorption rate, when given orally, is moderate, and peak plasma concentration occurs after about 2–4 hours. However, the extent of absorption is not well known. Celecoxib has the affinity to bind extensively to plasma proteins, especially to plasma albumin. It has an apparent volume of distribution (V) of 455 +/- 166 L in humans and the area under the plasma concentration-time curve (AUC) increases proportionally to increased oral doses, between 100 and 800 mg. Celecoxib is metabolized primarily by CYP2C9 isoenzyme to carboxylic acid and also by non-CYP-dependent glucuronidation to glucuronide metabolites. The metabolites are excreted in urine and feces, with a small proportion of unchanged drug (2%) in the urine. Its elimination half-life is about 11 hours (6–12 hours) in healthy individuals, but racial differences in drug disposition and pharmacokinetic changes in the elderly have been reported. People with chronic kidney disease appear to have 43% lower plasma concentration compared to healthy individuals, with a 47% increase in apparent clearance, and it can be expected that patients with mild to moderate hepatic impairment have increased steady-state AUC.