Selective COX-2 inhibitors (coxibs) are approved for the relief of acute pain and symptoms of chronic inflammatory conditions
such as osteoarthritis (OA) and rheumatoid arthritis (RA). They have similar pharmacological properties but a slightly improved
gastrointestinal (GI) safety profile if compared to traditional nonsteroidal anti-inflammatory drugs (tNSAIDs). However, long-term
use of coxibs can be associated with an increased risk for cardiovascular (CV) adverse events (AEs). For this reason, two
coxibs were withdrawn from the market. Currently celecoxib, etoricoxib, and lumiracoxib are used. These three coxibs differ
in their chemical structure and selectivity for COX-2, which might explain some of their pharmacological features. Following
oral administration, the less lipophilic celecoxib has a lower bioavailability (20–40%) than the other two coxibs (74–100%).
All are eliminated by hepatic metabolism involving mainly CYP2C9 (celecoxib, lumiracoxib) and CYP3A4 (etoricoxib). Elimination
half-life varies from 5 to 8 h (lumiracoxib), 11 to 16 h (celecoxib) and 19 to 32 h (etoricoxib). In patients with liver disease,
plasma levels of celecoxib and etoricoxib are increased about two-fold. Clinical efficacies of the coxibs are comparable to
tNSAIDs. There is an ongoing discussion about whether the slightly better GI tolerability (which is lost if acetylsalicylic
acid is coadministered) of the coxibs is offset by their elevated risks for CV AEs (also seen with tNSAIDs other than naproxen),
which apparently increase with dose and duration of exposure. In addition, the higher costs for coxibs (if compared to tNSAIDs,
even when a “gastroprotective” proton pump inhibitor is coadministered) should be taken into consideration, if a coxib will
be selected for certain patients with a high risk for GI complications. For such treatment, the lowest effective dose should
be used for a limited time. Monitoring of kidney function and blood pressure appears advisable. It is hoped that further controlled
studies can better define the therapeutic place of the coxibs.
Keywords COX-2 inhibitors - Pharmacokinetics - Pharmacodynamics - Clinical efficacy - Safety