Absorption and distribution of etoricoxib in plasma, CSF, and wound tissue in patients following hip surgery--a pilot study.

The perioperative administration of selective cyclooxygenase-2 (COX-2)-inhibitors to avoid postoperative pain is an attractive option: they show favorable gastro-intestinal tolerability, lack inhibition of blood coagulation, and carry a low risk of asthmatic attacks. The purpose of this study was to determine the cerebrospinal fluid (CSF), plasma, and tissue pharmacokinetics of orally administered etoricoxib and to compare it with effect data, i.e., COX-2-inhibition in patients after hip surgery. The study was performed in a blinded, randomized, parallel group design. A total of 12 adult patients were included who received 120 mg etoricoxib (n = 8) or placebo (n = 4) on day 1 post-surgery. Samples from plasma, CSF, and tissue exudates were collected over a period of 24 h post-dosing and analyzed for etoricoxib and prostaglandin E(2) (PGE(2)) using liquid chromatography-tandem mass spectrometry and immuno-assay techniques. CSF area under the curve (AUC) [AUCs((O-24h))] for etoricoxib amounted to about 5% of the total AUC in plasma (range: 2-7%). Individual CSF lag times with respect to (50%) peak plasma concentration were

Influence of plasma protein on the potencies of inhibitors of cyclooxygenase-1 and -2.

It is widely believed that the potencies of nonsteroid anti-inflammatory drugs (NSAIDs) as inhibitors of cyclooxygenase (COX) are influenced by protein binding in the extracellular fluid, since NSAIDs are bound to circulating albumin by well over 95%. This is an important point because the protein concentrations in synovial fluid and the central nervous system, which are sites of NSAID action, are markedly different from those in plasma. Here we have used a modified whole-blood assay to compare the potencies of aspirin, celecoxib, diclofenac, indomethacin, lumiracoxib, meloxicam, naproxen, rofecoxib, sodium salicylate, and SC560 as inhibitors of COX-1 and COX-2 in the presence of differing concentrations of protein. The potencies of diclofenac, naproxen, rofecoxib, and salicylate, but not aspirin, celecoxib, indomethacin, lumiracoxib, meloxicam, or SC560, against COX-1 (human platelets) increased as protein concentrations were reduced. Varying protein concentrations did not affect the potencies of any of the drugs against COX-2, with the exception of sodium salicylate (A549 cells). Clearly, our findings show that the selectivity of inhibitors for COX-1 and COX-2, which are taken to be linked to their efficacy and side effects, may change in different extracellular fluid conditions. In particular, selectivity in one body compartment does not demonstrate selectivity in another. Thus, whole-body safety or toxicity cannot be linked to one definitive measure of COX selectivity.