Valdecoxib

Valdecoxib is a diaryl-substituted isoxazole and selective cyclooxygenase-2 (COX-2) inhibitor. It is identified by CAS 181695-72-7 and the Pfizer reference code PF-00579925. Formerly marketed as Bextra for osteoarthritis, adult rheumatoid arthritis, and primary dysmenorrhea, it was withdrawn from the U.S. market in 2005 after FDA concluded that its overall risk-benefit profile was unfavorable, particularly because of cardiovascular risk and serious, potentially life-threatening skin reactions.

Its pharmacology remains relevant to prostanoid signaling, inflammation, analgesia, and COX-2 inhibitor safety. Valdecoxib is also the active form generated from parecoxib, an injectable prodrug converted by hydrolysis after administration.

Application of Valdecoxib

Valdecoxib is used in COX-1/COX-2 selectivity assays, prostaglandin measurements, inflammatory cell models, and comparative NSAID studies. It helps connect enzyme inhibition with downstream inflammatory responses and supports investigation of gastrointestinal, platelet, cardiovascular, and dermatologic outcomes.

For computational workflows, the Valdecoxib SMILES representation supports structure searches, descriptor calculation, and compound registration. Its relationship with parecoxib also enables comparison of direct exposure with prodrug conversion in pharmacokinetic studies.

In Vitro

Testing of the Valdecoxib structure against human recombinant enzymes produced IC50 values of 0.005 µM for COX-2 and 150 µM for COX-1. This marked selectivity is assay-specific and should not be transferred directly to cellular or in vivo systems.

Cellular response depends on COX expression, substrate availability, compound concentration, and the prostanoid pathways present in the selected model.

In Vivo

Animal studies of Pfizer Valdecoxib demonstrated anti-inflammatory, analgesic, and antipyretic activity. In clinical use, valdecoxib provided symptomatic relief, while parecoxib generated valdecoxib as its circulating active compound.

Cardiovascular events were a particular concern after coronary artery bypass graft surgery. Serious skin reactions, including Stevens-Johnson syndrome and toxic epidermal necrolysis, were also reported. The FDA requested withdrawal of Bextra from the U.S. market in April 2005; the European Commission suspended the Bextra marketing authorization in October 2005.

Biochemical and Physiological Actions

The Valdecoxib molecular structure supports binding within the COX-2 active-site channel and blocks formation of prostanoid precursors from arachidonic acid. This reduces inflammatory prostaglandin synthesis while having less direct effect on platelet COX-1 and thromboxane production.

COX-2 selectivity does not remove cardiovascular risk. Reduced vascular prostacyclin without comparable platelet thromboxane inhibition may favor a prothrombotic imbalance. Metabolism mainly through CYP3A4 and CYP2C9 is relevant to pharmacokinetic and interaction studies.

Features and Benefits of Valdecoxib

• Defined Valdecoxib chemical structure based on a methylphenylisoxazole and benzenesulfonamide scaffold.
• Valdecoxib molecular weight of 314.36 g/mol for the formula C16H14N2O3S.
• High COX-2 selectivity in human recombinant enzyme assays.
• Direct relationship to parecoxib for prodrug and metabolite research.
• Well-documented clinical and safety evidence for translational NSAID studies.